Silicon-based slow-release potash fertilizer and its manufacturing method

Abstract

The invention relates to a silicon-based slow-release potash fertilizer and a method for making the same, and more specifically to a silicon-based slow-release potash fertilizer made from potassium-containing rock resources and a method for making the same. The silicon-based slow-release potash fertilizer does not contain acidogenic factors such as chlorine and sulfate, is environmentally friendly, and after being applied to the soil, can release nutrient elements such as K, Si, Ca, Mg, Fe, etc. contained therein and be absorbed and utilized by crops, can neutralize acidogenic substances in the soil, and can also improve the cation exchange capacity and water and fertilizer retention capacity of the soil.

Description

[0001] This application is a divisional application of the patent application with application number 201880094077.6 and name “Silicon-based slow-release potash fertilizer and its manufacturing method”. The application date of the above-mentioned parent case (201880094077.6) is May 31, 2018. Technical Field

[0002] The invention relates to a silicon-based slow-release potash fertilizer and a method for producing the same, and more particularly to a silicon-based slow-release potash fertilizer produced by utilizing potassium-containing rock resources and a method for producing the same. Background Art

[0003] Potassium is one of the three essential elements for plants and plays an irreplaceable role in increasing crop yield and improving quality. Although common water-soluble potassium fertilizers such as potassium chloride and potassium sulfate have been widely used, they also expose many shortcomings: (1) Potassium chloride, potassium sulfate and other potassium fertilizers are water-soluble potassium fertilizers, which have the risk of leaching, low utilization rate, and cause pollution of surface water and groundwater; (2) The ratio of potassium to chlorine in potassium chloride and the ratio of potassium to sulfur in potassium sulfate are seriously inconsistent with the ratio of potassium, sulfur and chlorine nutrients absorbed by plants, resulting in a large amount of chloride ions and sulfate ions remaining in the soil, leading to soil salinization, acidification, and compaction; (3) After the application of potassium chloride, the residual chloride ions migrate with water and carry away exchangeable cations such as calcium and magnesium in the soil, resulting in soil calcium and magnesium deficiency, and aggravating soil acidification. (4) Improper use of potassium chloride and potassium sulfate can cause seedling burn to plants.

[0004] The drawbacks of water-soluble fertilizers have led to more and more attention paid to slow-release fertilizers. At present, the main type of slow-release fertilizers / potash fertilizers is the coated slow-release type, which uses soluble potassium salts as raw materials and uses sulfur or resin to coat the soluble potassium salts to achieve slow release of potassium. However, the harm caused by the residual substances after the nutrients of this type of product are released to agriculture and the environment has become the biggest problem in the promotion of this type of product.

[0005] In nature, most potassium is fixed in some insoluble minerals, such as potassium-containing rock resources such as potassium feldspar and mica. These minerals are difficult to decompose or release enough potassium nutrients to supply crop growth. Therefore, predecessors have done a lot of work in decomposing and utilizing potassium-containing rock resources and preparing potassium salts and potassium fertilizers. They can be mainly divided into two categories: the first method is to prepare potassium salts such as potassium carbonate, potassium sulfate, and potassium chloride, including high-temperature decomposition of potassium feldspar with additives containing elements such as Ca, Mg, or Na, so that the potassium in potassium feldspar is converted into water-soluble potassium, and then through several leaching steps and solid-liquid separation steps, potassium salt products, silicon-aluminum products, etc. are prepared respectively; including wet decomposition of potassium feldspar with fluorine-containing acidic media, and then preparing different products of potassium, aluminum, and silicon respectively. This type of method has not been industrially applied because of the long process, complex process, large amount of by-products and difficult to handle. The second method changes the idea of ​​separating potassium, aluminum, and silicon from potassium feldspar, and uses additives or bacterial agents to decompose potassium feldspar without separation, but directly uses the product as a product. This type of method adds a large amount of additives, resulting in a low potassium oxide content in the product, with a K2O content of 4-6%. The product has low added value and is not considered a potash fertilizer because the potassium content is too low, but rather a soil conditioner containing calcium and silicon.

[0006] Therefore, there is an urgent need for new slow-release potash fertilizers to overcome the above-mentioned shortcomings. Summary of the invention

[0007] A first aspect of the present invention provides a silicon-based slow-release potash fertilizer comprising (a) KAlSiO4 crystals and (b) at least one substance selected from K2O-Fe2O3-SiO2 system crystals, K2O-CaO-SiO2 system crystals, K2O-MgO-SiO2 system crystals, CaO-SiO2 system crystals, CaO-MgO-SiO2 system crystals and a potassium-silicon-containing glass.

[0008] In some embodiments, in the silicon-based slow-release potash fertilizer of the present invention, (b) is at least one crystal selected from K2O-Fe2O3-SiO2 system crystals, K2O-CaO-SiO2 system crystals, K2O-MgO-SiO2 system crystals, CaO-SiO2 system crystals and CaO-MgO-SiO2 system crystals, and a glassy body containing potassium silicon.

[0009] In some embodiments, the K2O-Fe2O3-SiO2 system crystals include KFeSiO4 crystals, K 1.11 Fe 1.11 Si 0.89 O4 crystals or mixtures thereof, etc.;

[0010] In some embodiments, the K2O-CaO-SiO2 system crystals include K2CaSiO4 crystals, K2Ca2Si2O7 crystals or mixtures thereof;

[0011] In some embodiments, the K2O-MgO-SiO2 system crystals include K 1.14 Mg 0.57 Si 1.43 O4 crystals, K2MgSiO4 crystals or mixtures thereof;

[0012] In some embodiments, the CaO-SiO2 system crystals include Ca3Si2O7 crystals, CaSiO3 crystals, Ca3(Si3O9) crystals or mixtures thereof;

[0013] In some embodiments, the CaO-MgO-SiO2 system crystals include Ca2MgSi2O7 crystals, CaMgSiO4 crystals, Ca 1.7 Mg 0.3 SiO4 crystals or mixtures thereof, etc.

[0014] In some embodiments, the silicon-based slow-release potash fertilizer of the present invention comprises (a) KAlSiO4 crystals and (b) a potassium carbonate selected from K2CaSiO4, K2Ca2Si2O7, K2MgSiO4, CaMgSiO4 and Ca 1.7 Mg 0.3 At least one crystal of SiO4.

[0015] In some embodiments, the silicon-based slow-release potash fertilizer of the present invention comprises (a) KAlSiO4 crystals, (b) a potassium carbonate selected from K2CaSiO4, K2MgSiO4, K2Ca2Si2O7, CaMgSiO4 and Ca 1.7 Mg 0.3 At least one of SiO4 crystals and a glass containing potassium silicon.

[0016] In some embodiments, the silicon-based slow-release potassium fertilizer of the present invention comprises (a) KAlSiO4 crystals and (b) a compound selected from KFeSiO4, K 1.11 Fe 1.11 Si 0.89 O4 and K 1.14 Mg 0.57 Si 1.43 At least one crystal of O4.

[0017] In some embodiments, the silicon-based slow-release potash fertilizer of the present invention comprises (a) KAlSiO4 crystals, (b) a compound selected from KFeSiO4, K 1.11 Fe 1.11 Si 0.89 O4 and K 1.14Mg 0.57 Si 1.43 At least one crystal of O4 and a glass containing potassium silicon.

[0018] In some embodiments, the silicon-based slow-release potash fertilizer of the present invention comprises (a) KAlSiO4 crystals and (b) at least one crystal selected from the group consisting of CaSiO3, Ca3Si3O9, Ca3Si2O7 and Ca2MgSi2O7.

[0019] In some embodiments, the silicon-based slow-release potash fertilizer of the present invention comprises (a) KAlSiO4 crystals, (b) at least one crystal selected from the group consisting of CaSiO3, Ca3Si3O9, Ca3Si2O7 and Ca2MgSi2O7, and a glass containing potassium silicon.

[0020] In some embodiments, the silicon-based slow-release potassium fertilizer of the present invention further comprises other nutrient components and / or difficult-to-decompose impurity components.

[0021] In some embodiments, in the silicon-based slow-release potash fertilizer of the present invention, based on the total weight of the silicon-based slow-release potash fertilizer, the effective K2O content is 10 to 40 weight %, the effective SiO2 content is 20 to 40 weight %, the effective CaO content is 0 to 30 weight %, and the effective MgO content is 0 to 15 weight %.

[0022] In some embodiments, in the silicon-based slow-release potash fertilizer of the present invention, based on the total weight of the silicon-based slow-release potash fertilizer, the effective content of the other nutrient components, such as but not limited to the oxides of iron, manganese, sodium, aluminum, boron, zinc, etc. contained therein, is 0 to 35% by weight, preferably 0 to 25% by weight, more preferably 0 to 15% by weight, and most preferably 0 to 5% by weight.

[0023] In some embodiments, in the silicon-based slow-release potash fertilizer of the present invention, the effective content of the difficult-to-decompose impurity component in the form of oxides is 0 to 35 weight %, preferably 0 to 25 weight %, more preferably 0 to 15 weight %, and most preferably 0 to 5 weight %, based on the total weight of the silicon-based slow-release potash fertilizer.

[0024] In some embodiments, the raw materials for producing the silicon-based slow-release potash fertilizer include (a) a potassium-containing material, (b) at least one material selected from an iron-containing material, an aluminum-containing material, a calcium-containing material, and a magnesium-containing material, and (c) at least one compound selected from potassium carbonate and potassium hydroxide.

[0025] In some embodiments, the potassium-containing material is a potassium-containing aluminosilicate material.

[0026] In some embodiments, the ratio of the components in the raw materials satisfies the following relationship: in the raw material obtained by combining and mixing the raw materials, the molar number Mol (Rx The ratio of the molar number Mol(SiO2) of the metal oxide to the molar number Mol(R O) of SiO2 is in the range of 0.50 to 2.0, for example but not limited to 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1.00, 1.05, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35, 1.40, 1.45, 1.50, 1.55, 1.60, 1.65, 1.70, 1.75, 1.80, 1.85, 1.90, 1.95 and 2.0, or the range between any of the above values, and the molar number Mol(R O) of the metal oxide to the molar number Mol(SiO2) of SiO2 is in the range of 0.50 to 2.0, for example but not limited to 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1.00, 1.05, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35, 1.40, 1.45, 1.50, 1.55, 1.60, 1.65, 1.70, 1.75, 1.80, 1.85, 1.90, 1.95 and 2.0, or the range between any of the above values, x O) is the sum of the molar numbers of metal oxides present in the raw material, wherein the metal oxides are selected from K2O, Na2O, Al2O3, Fe2O3, CaO and MgO, etc.

[0027] In some embodiments, it is preferred that the molar number Mol (R x The ratio of the molar number of O) to SiO2, Mol(SiO2), is in the range of 0.80 to 1.50.

[0028] A second aspect of the present invention provides a method for producing a silicon-based slow-release potash fertilizer, the method comprising the following steps:

[0029] (1) Raw meal preparation: (a) a potassium-containing material, (b) at least one material selected from the group consisting of an iron-containing material, an aluminum-containing material, a calcium-containing material and a magnesium-containing material, and (c) at least one compound selected from the group consisting of potassium carbonate and potassium hydroxide are mixed to prepare the raw meal;

[0030] (2) Raw material heating: placing the prepared raw material in a temperature range of 900 to 1300° C. for 15 to 180 minutes to prepare the raw material;

[0031] (3) Clinker processing: The clinker is cooled and then crushed to obtain the silicon-based slow-release potash fertilizer.

[0032] In some embodiments, the potassium-containing material is a potassium-containing aluminosilicate material.

[0033] In some embodiments, the molar number Mol (R xThe ratio of the molar number Mol(SiO2) of the metal oxide to the molar number Mol(R O) of SiO2 is in the range of 0.50 to 2.0, for example but not limited to 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1.00, 1.05, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35, 1.40, 1.45, 1.50, 1.55, 1.60, 1.65, 1.70, 1.75, 1.80, 1.85, 1.90, 1.95 and 2.0, or the range between any of the above values, and the molar number Mol(R O) of the metal oxide to the molar number Mol(SiO2) of SiO2 is in the range of 0.50 to 2.0, for example but not limited to 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1.00, 1.05, 1.10, 1.15, 1.20, 1.25, 1.30, 1.35, 1.40, 1.45, 1.50, 1.55, 1.60, 1.65, 1.70, 1.75, 1.80, 1.85, 1.90, 1.95 and 2.0, or the range between any of the above values, x O) is the sum of the molar numbers of metal oxides present in the raw material, wherein the metal oxides are selected from K2O, Na2O, Al2O3, Fe2O3, CaO and MgO, etc.

[0034] In some embodiments, the heating temperature in the method for producing the silicon-based slow-release potassium fertilizer of the present invention is in the range of 900 to 1250°C.

[0035] In some embodiments, the heating time in the method for producing the silicon-based slow-release potash fertilizer of the present invention is in the range of 30 to 180 minutes.

[0036] In some embodiments, in the method for producing the silicon-based slow-release potash fertilizer of the present invention, the clinker is ground into powder to obtain a powdery product.

[0037] In some embodiments, in the method for producing the silicon-based slow-release potassium fertilizer of the present invention, the clinker is granulated to obtain a granular product.

[0038] The method for producing the silicon-based slow-release potash fertilizer provided in the second aspect of the present invention can produce the silicon-based slow-release potash fertilizer provided in the first aspect of the present invention.

[0039] Therefore, the present invention uses potassium-containing rock resources as raw materials to produce environmentally friendly silicon-based slow-release potash fertilizers with silicate as anions that are free of acidogenic factors such as chlorine and sulfate, and have an affinity with the soil. After the silicon-based slow-release potash fertilizer of the present invention is applied to the soil, it can release the nutrient elements such as K, Si, Ca, Mg, Fe contained therein and be absorbed and utilized by crops in an active and passive manner, and can also neutralize the acidogenic substances in the soil. In addition, the aluminum-silicon colloidal substances left behind can also improve the cation exchange capacity and water and fertilizer retention capacity of the soil. The slow-release potash fertilizer can control the nutrient release period of the product by adjusting the raw materials and process conditions, thereby adjusting the composition and structure of the product, so as to meet different crop needs and soil conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The foregoing aspects and advantages of the methods and compositions described herein will become more readily appreciated as the present invention is better understood by reference to the following detailed description taken in conjunction with the accompanying drawings, wherein:

[0041] Figure 1 This is the X-ray powder diffraction pattern of the silicon-based slow-release potash fertilizer obtained in Example 1 of the present invention.

[0042] Figure 2 This is the X-ray powder diffraction pattern of the silicon-based slow-release potash fertilizer obtained in Example 2 of the present invention.

[0043] Figure 3 This is the X-ray powder diffraction pattern of the silicon-based slow-release potash fertilizer obtained in Example 3 of the present invention.

[0044] Figure 4 It is the X-ray powder diffraction pattern of the silicon-based slow-release potash fertilizer obtained in Example 4 of the present invention.

[0045] Figure 5 This is the X-ray powder diffraction pattern of the silicon-based slow-release potash fertilizer obtained in Example 5 of the present invention.

[0046] Figure 6 This is the X-ray powder diffraction pattern of the silicon-based slow-release potash fertilizer obtained in Example 6 of the present invention.

[0047] Figure 7 This is the X-ray powder diffraction pattern of the silicon-based slow-release potash fertilizer obtained in Example 7 of the present invention. DETAILED DESCRIPTION

[0048] It should be appreciated that certain aspects, modes, embodiments, variations and features of the technology disclosed herein are described below in various levels of detail to provide a substantial understanding of the technology and should not be construed as limiting the scope of protection as defined in the appended claims.

[0049] The potassium-containing materials used in the present invention include potassium-containing aluminosilicate ore resources with KAlSi3O8 as the main mineral composition, such as syenite, potassium-rich shale, potassium-rich slate, and potassium-rich phonolite, and also include potassium-containing aluminosilicate resources with leucite (KAlSi2O6) or mica (H2KAl3(SiO4)3) as the main mineral phase.

[0050] When decomposing and utilizing potassium feldspar and other potassium-containing aluminum silicate minerals, predecessors added a large amount of additives, mainly alkali metal oxides and / or alkaline earth metal oxides, in order to decompose these aluminum silicate minerals to generate substances such as K2O·Al2O3, Na2O·Al2O3, 3CaO·Al2O3, K2O·SiO2, Na2O·SiO2 or 2CaO·SiO2, 3CaO·SiO2, etc. The added additive oxides need to be combined with the silicon in the potassium-containing minerals as well as the aluminum and iron therein, resulting in a large amount of additives added. The fundamental reason for this is that the inherent cognition of the agricultural field on plant absorption of potassium is that potassium can only be absorbed by plants in ionic form, and mineral potassium can basically not be used by plants, so the research focus of predecessors has been on converting potassium in potassium-containing rocks into water-soluble potassium; predecessors also used a method of high-temperature melting and quenching to convert all aluminum silicate minerals into amorphous glassy substances for use as fertilizers, but this method requires melting the material at a high temperature, and the molten material is not easy to operate in actual applications, and the equipment container is prone to corrosion.

[0051] Different from the previous processes or principles, the key of the present invention is to utilize the oxides such as K2O, Al2O3 and SiO2 and their proportions contained in potassium-containing aluminosilicate minerals, such as KAlSi3O8, in which Mol(K2O) / Mol(Al2O3) / Mol(SiO2) is 1 / 1 / 6. Through this process, 2 / 3 of SiO2 is removed from KAlSi3O8 and converted into KAlSiO4, a mineral soluble in weak acid, and other added oxides are combined with the removed SiO2 to form some mineral crystals or solid solutions that can be dissolved by weak acid, including K2O-Fe2O3-SiO2 system crystals, K2O-CaO-SiO2 system crystals, K2O-MgO-SiO2 system crystals, CaO-SiO2 system crystals, CaO-MgO-SiO2 system crystals, potassium-silicon glass, etc.

[0052] As used herein, the term "K2O-Fe2O3-SiO2 system crystal" refers to a crystalline substance existing in the K2O, Fe2O3, SiO2 ternary system (phase diagram) with K2O, Fe2O3, and SiO2 as components. The K2O-Fe2O3-SiO2 system crystal may include, for example, but not limited to, KFeSiO4 crystal, K 1.11 Fe 1.11 Si 0.89 O4 crystals, and mixtures of any proportions thereof.

[0053] As used herein, the term "K2O-CaO-SiO2 system crystal" refers to a crystalline substance existing in the K2O, CaO, SiO2 ternary system (phase diagram) with K2O, CaO, and SiO2 as constituent components. The K2O-CaO-SiO2 system crystal may include, for example but not limited to, K2CaSiO4 crystal, K2Ca2Si2O7 crystal, and a mixture of any proportion of these crystals.

[0054] As used herein, the term "K2O-MgO-SiO2 system crystal" refers to a crystalline substance existing in the K2O, MgO, SiO2 ternary system (phase diagram) with K2O, MgO, and SiO2 as components. The K2O-MgO-SiO2 system crystal may include, for example, but not limited to K 1.14 Mg 0.57 Si 1.43 O4 crystals, K2MgSiO4 crystals, and mixtures of these crystals in any proportion.

[0055] As used herein, the term "CaO-SiO2 system crystal" refers to a crystalline substance existing in a CaO, SiO2 binary system (phase diagram) with CaO and SiO2 as components. The CaO-SiO2 system crystal may include, for example but not limited to, Ca3Si2O7 crystal, CaSiO3 crystal, Ca3(Si3O9) crystal, and a mixture of any proportion of these crystals.

[0056] As used herein, the term "CaO-MgO-SiO2 system crystal" refers to a crystalline substance existing in the CaO, MgO, SiO2 ternary system (phase diagram) with CaO, MgO, and SiO2 as components. The CaO-MgO-SiO2 system crystal may include, for example, but is not limited to, Ca2MgSi2O7 crystal, CaMgSiO4 crystal, Ca 1.7 Mg 0.3 SiO4 crystals, and mixtures of these crystals in any proportion.

[0057] When the various system crystals described above are crystal mixtures, the contents of the various single crystals contained therein can be any proportions, as long as the effective components in the silicon-based slow-release potassium fertilizer of the present invention satisfy the following relationship: in the silicon-based slow-release potassium fertilizer of the present invention, the effective K2O content is 10-40% by weight, the effective SiO2 content is 20-40% by weight, the effective CaO content is 0-30% by weight, and the effective MgO content is 0-15% by weight, based on the total weight of the silicon-based slow-release potassium fertilizer. In the present invention, the effective oxide component content refers to the chemical effective oxide component content, which is measured and calculated by the following leaching method, which comprises: weighing 1.0g of powdered silicon-based slow-release potassium fertilizer, pouring it into a 250mL conical flask, adding 150mL of a 0.5mol / L hydrochloric acid solution preheated to 30°C into the conical flask, and plugging the flask tightly. Place the conical flask in a water bath constant temperature oscillation box and oscillate at 28-30°C for 60 minutes. Dry filter and detect the content of each oxide in the filtrate, from which the content of the effective oxide component can be calculated.

[0058] As used herein, the term "potassium-silicon-containing glass" refers to a glassy material comprising K2O and SiO2.

[0059] Based on the law of conservation of energy and the corresponding relationship between energy and material activity, the easier it is to decompose or dissolve a substance, the higher its activity is and the higher the energy it contains (that is, more energy is required to convert it to this state). Water-soluble substances are more active than substances that are insoluble in water but soluble in weak acids. Therefore, converting acid-insoluble substances such as potassium-containing rocks into weakly acid-soluble substances will greatly reduce conversion energy consumption and save resources compared to converting them into water-soluble substances.

[0060] The raw material ratio of the present invention is required to meet the requirements of R x The molar ratio of O / SiO2 is Mol(R x O) / Mol(SiO2) is between 0.50 and 2.0, of which Mol(R x R2O) represents the sum of the molar numbers of metal oxides present in the raw material, wherein the metal oxides are selected from K2O, Na2O, Al2O3, Fe2O3, CaO and MgO, etc., i.e., R2O in the clinker or product x The molar ratio of O / SiO2 is between 0.50 and 2.0 (the main oxides K2O, Na2O, Al2O3, Fe2O3, CaO, MgO and SiO2 in the mixed raw material hardly volatilize during the treatment process). The preferred molar ratio Mol(R xO) / Mol(SiO2) is between 0.80 and 1.50. In the raw potassium-containing rock, potassium feldspar generally coexists with potassium and sodium feldspar. Pure potassium feldspar hardly exists in nature. Therefore, the raw material must contain Na2O, and Na2O plays almost the same role as K2O. Therefore, when calculating the ratio, it is usually necessary to combine Na2O with K2O. In different embodiments of the present invention, the silicon-based slow-release potassium fertilizer includes but is not limited to the following specific components, such as KAlSiO4, KFeSiO4, K 1.11 Fe 1.11 Si 0.89 O4, K2CaSiO4, K2Ca2Si2O7, K 1.14 Mg 0.57 Si 1.43 O4, K2MgSiO4, Ca3Si2O7, CaSiO3, Ca3(Si3O9), Ca2MgSiO7, CaMgSiO4, Ca 1.7 Mg 0.3 Crystals such as SiO4 and glass containing potassium silicon, the R x The molar ratio of O / SiO2 is shown in Table 1 below.

[0061] Table 1. Mol (R) of each component x O) / Mol(SiO2) ratio

[0062] Composition <![CDATA[Mol(R x O) / Mol(SiO2)]]> <![CDATA[KAlSiO4]]> 1.0 <![CDATA[KFeSiO4]]> 1.0 <![CDATA[K 1.11 Faith 1.11 Yeah 0.89 O4]]> 1.2 <![CDATA[K2CaSiO4]]> 2.0 <![CDATA[K2Ca2Si2O7]]> 1.5 <![CDATA[K 1.14 Mg 0.57 Whom 1.43 O4]]> 0.8 <![CDATA[K2MgSiO4]]> 2.0 <![CDATA[Ca3Si2O7]]> 1.5 <![CDATA[CaSiO3]]> 1.0 <![CDATA[Ca3(Si3O9)]]> 1.0 <![CDATA[Ca2MgSi2O7]]> 1.5 <![CDATA[CaMgSiO4]]> 2.0 <![CDATA[Ca 1.7 Mg 0.3 SiO4]]> 2.0 Potassium-silicon glass 0-1.0

[0063] In the present invention, the Mol (R x The range of Mol(O) / Mol(SiO2) is between 0.50 and 2.0, and preferably the ratio is between 0.80 and 1.50. x When the ratio of Mol(R O) / Mol(SiO2) is lower than 0.80, it indicates that the amount of potassium-silicon-containing glass in the silicon-based slow-release potassium fertilizer increases and the amount of KAlSiO4 decreases, which affects the nutrient release of the silicon-based slow-release potassium fertilizer; x When the ratio of CaMgSiO4 and CaO2 is higher than 1.50, it indicates that the content of CaMgSiO4 and CaO2 in silicon-based slow-release potassium fertilizer is 1.7 Mg 0.3 The increase in the amount of SiO4 or the presence of substances with a high alkali-silicon ratio such as Ca2SiO4 and Ca3SiO5 leads to an increase in the amount of additives such as potassium, calcium, and magnesium, which is contrary to the original intention of the present invention to reduce the amount of additives.

[0064] In some embodiments, the silicon-based slow-release potash fertilizer of the present invention comprises (a) KAlSiO4 and (b) a compound selected from K2CaSiO4, K2Ca2Si2O7, K2MgSiO4, CaMgSiO4, Ca 1.7 Mg 0.3 When at least one of SiO4 and Ca3Si2O7 is used, its Mol(R x The ratio of Mol(O) / Mol(SiO2) is preferably between 1.10 and 1.50, and more preferably between 1.20 and 1.40. Therefore, when manufacturing silicon-based slow-release potash fertilizer, the molar number of metal oxides in the mixed raw material Mol(R x The ratio of the molar number of O) to SiO2, Mol(SiO2), is preferably between 1.10 and 1.50, and more preferably between 1.20 and 1.40.

[0065] In some embodiments, the silicon-based slow-release potassium fertilizer of the present invention comprises (a) KAlSiO4 and (b) a compound selected from KFeSiO4, K 1.11 Fe 1.11 Si 0.89 O4, K 1.14 Mg 0.57 Si 1.43 When at least one of O4 is present, its Mol(R x The ratio of Mol(O) / Mol(SiO2) is preferably between 0.90 and 1.20, and more preferably between 1.00 and 1.10. Therefore, when manufacturing silicon-based slow-release potash fertilizer, the molar number of metal oxides in the mixed raw material Mol(R x The ratio of the molar number of SiO2 (Mol(SiO2)) to that of SiO2 is preferably between 0.90 and 1.20, more preferably between 1.00 and 1.10.

[0066] In some embodiments, when the silicon-based slow-release potassium fertilizer of the present invention comprises (a) KAlSiO4 and (b) at least one selected from CaSiO3, Ca3(Si3O9), Ca2MgSi2O7 and a glass containing potassium silicon, its Mol(R x The ratio of Mol(O) / Mol(SiO2) is preferably between 0.80 and 1.10, and more preferably between 0.90 and 1.00. Therefore, when manufacturing silicon-based slow-release potash fertilizer, the molar number of metal oxides in the mixed raw material Mol(R x The ratio of the molar number of O) to SiO2, Mol(SiO2), is preferably between 0.80 and 1.10, and more preferably between 0.90 and 1.00.

[0067] When potassium-containing rock is used as potassium-containing material and aluminum-containing material or iron-containing material is added, the reaction mechanism includes the following reaction, wherein the aluminum-containing material includes bauxite and industrial by-products containing Al2O3 or Al(OH)3; the iron-containing material includes iron ore, magnetite, specularite and materials rich in Fe2O3 or FeO, the aluminum-containing material or iron-containing material is represented in the reaction formula as its oxide, and potassium carbonate and potassium hydroxide will remove CO2 and H2O respectively in the reaction, and are represented by K2O in the reaction formula.

[0068] KAlSi3O8+Al2O3+K2O→KAlSiO4

[0069] KAlSi3O8+Fe2O3+K2O→KAlSiO4+K2O-Fe2O3-SiO2 system crystal

[0070] Specific reactions include, for example:

[0071] KAlSi3O8+Fe2O3+K2O→KAlSiO4+KFeSiO4

[0072] KAlSi3O8+Fe2O3+K2O→KAlSiO4+K 1.11 Fe 1.11 Si 0.89 O4

[0073] KAlSi2O6+Al2O3+K2O→KAlSiO4

[0074] KAlSi2O6+Fe2O3+K2O→KAlSiO4+K2O-Fe2O3-SiO2 system crystal

[0075] Specific reactions include, for example:

[0076] KAlSi2O6+Fe2O3+K2O→KAlSiO4+KFeSiO4

[0077] KAlSi2O6+Fe2O3+K2O→KAlSiO4+K 1.11 Fe 1.11 Si 0.89 O4

[0078] H2KAl3(SiO4)3+K2O→KAlSiO4+H2O

[0079] Potassium-containing minerals in potassium-containing rocks are partially desiliconized and converted into KAlSiO4. The desiliconized reacts with K2O, Al2O3 or Fe2O3 to form crystalline minerals of KAlSiO4 or K2O-Fe2O3-SiO2 system, such as KFeSiO4, K 1.11 Fe1.11 Si 0.89 O4, etc.

[0080] When potassium-containing rock is used as potassium-containing material and calcium-containing material is added, the reaction mechanism is as follows, wherein the calcium-containing material includes limestone, quicklime, slaked lime and carbide slag, etc., which will be converted into oxides during the reaction and are uniformly represented by CaO in the reaction formula. Potassium carbonate and potassium hydroxide will remove CO2 and H2O respectively during the reaction and are represented by K2O in the reaction formula.

[0081] KAlSi3O8+CaO+K2O→KAlSiO4+K2O-CaO-SiO2 system crystal

[0082] Specific reactions include, for example:

[0083] KAlSi3O8+CaO+K2O→KAlSiO4+K2CaSiO4

[0084] KAlSi3O8+CaO+K2O→KAlSiO4+K2Ca2Si2O7

[0085] KAlSi3O8+CaO+K2O→KAlSiO4+potassium-silicon-containing glass+CaO-SiO2 system crystal

[0086] KAlSi2O6+CaO+K2O→KAlSiO4+K2O-CaO-SiO2 system crystal

[0087] Specific reactions include, for example:

[0088] KAlSi2O6+CaO+K2O→KAlSiO4+K2CaSiO4

[0089] KAlSi2O6+CaO+K2O→KAlSiO4+K2Ca2Si2O7

[0090] KAlSi2O6+CaO+K2O→KAlSiO4+potassium-silicon-containing glass+CaO-SiO2 system crystal

[0091] In this way, the substances in potassium-containing rocks are partially desiliconized and converted into KAlSiO4. The removed SiO2 combines with CaO and K2O to form K2O-CaO-SiO2 system crystals (such as K2CaSiO4, K2Ca2Si2O7, etc.), CaO-SiO2 system crystals (such as CaSiO3, Ca3(Si3O9), Ca3Si2O7) or potassium-silicon-containing glass.

[0092] When potassium-containing rock is used as potassium-containing material and magnesium-containing material is added, the reaction mechanism is as follows, wherein the magnesium-containing material includes magnesite, brucite, dolomite, etc., which are converted into corresponding oxides during the reaction process and are uniformly represented by MgO in the reaction formula, and dolomite is represented by MgO+CaO. Potassium carbonate and potassium hydroxide will remove CO2 and H2O respectively during the reaction, and are represented by K2O in the reaction formula.

[0093] KAlSi3O8+MgO+K2O→KAlSiO4+K2O-MgO-SiO2 system crystal

[0094] Specific reactions include, for example:

[0095] KAlSi3O8+MgO+K2O→KAlSiO4+K2MgSiO4

[0096] KAlSi3O8+MgO+K2O→KAlSiO4+K 1.14 Mg 0.57 Si 1.43 O4

[0097] KAlSi3O8+CaO+MgO+K2O→KAlSiO4+potassium-containing silica glass+CaO-MgO-SiO2 system crystal

[0098] KAlSi2O6+MgO+K2O→KAlSiO4+K2O-MgO-SiO2 system crystal

[0099] Specific reactions include, for example:

[0100] KAlSi2O6+MgO+K2O→KAlSiO4+K2MgSiO4

[0101] KAlSi2O6+MgO+K2O→KAlSiO4+K 1.14 Mg 0.57 Si 1.43 O4

[0102] KAlSi2O6+CaO+MgO+K2O→KAlSiO4+potassium-containing silica glass+CaO-MgO-SiO2 system crystal

[0103] The substances in potassium-containing rocks are partially desiliconized and converted into KAlSiO4. The desiliconized SiO2 combines with MgO, K2O, and CaO to form K2O-MgO-SiO2 system crystals, CaO-MgO-SiO2 system crystals, potassium-containing silicon glass, etc. 1.14 Mg 0.57 Si 1.43O4, Ca2MgSi2O7, CaMgSiO4, Ca 1.7 Mg 0.3 SiO4, etc.

[0104] In the silicon-based slow-release potash fertilizer made from potassium-containing rock as raw material, each potassium-containing active mineral or substance has its own characteristics and functions. Different combinations obtained by the method of the present invention can achieve different product application characteristics.

[0105] The theoretical nutrient contents of these generated active crystalline minerals or substances are shown in Table 2, where the theoretical nutrient contents are expressed in percentages of K2O, SiO2, CaO, and MgO:

[0106] Table 2. Theoretical composition and nutrient content of active crystalline minerals or substances

[0107] Substances containing potassium <![CDATA[K2O content / %]]> <![CDATA[SiO2 content / %]]> CaO content / % MgO content / % KAlSiO4 29.78 37.99 0 0 <![CDATA[KFeSiO4]]> 25.18 32.12 0 0 <![CDATA[K 1.11 Faith 1.11 Yeah 0.89 O4]]> 26.90 27.51 0 0 <![CDATA[K2CaSiO4]]> 44.78 28.56 26.66 0 <![CDATA[K2Ca2Si2O7]]> 28.85 36.80 34.35 0 <![CDATA[CaSiO3 / Ca3Si3O9]]> 0 51.72 48.28 0 <![CDATA[Ca3Si2O7]]> 0 41.66 58.34 0 Potassium-silicon glass indefinite indefinite indefinite indefinite <![CDATA[K2MgSiO4]]> 48.41 30.88 0 20.71 <![CDATA[K 1.14 Mg 0.57 Whom 1.43 O4]]> 33.03 52.84 0 14.13 <![CDATA[CaMgSiO4]]> 0 38.40 35.84 25.76 <![CDATA[Ca2MgSi2O7]]> 0 44.08 41.14 14.78

[0108] These active substances have different properties due to their different compositions and structures, and they will affect each other in combination to show the characteristics and rules of each combination. K2CaSiO4, K2MgSiO4, K2Ca2Si2O7, etc. have high activity and high K2O content, and are easily hydrolyzed in water. These substances can be used as fast-acting nutrients and can be used for crops with short growth cycles or high potassium requirements in the early stages. KAlSiO4, KFeSiO4, K 1.11 Fe 1.11 Si 0.89 O4, K 1.14 Mg 0.57 Si 1.43 The K2O content of O4 is not low. These potassium-containing active substances are insoluble or slightly soluble in water, can be dissolved by weaker weak acids, have a short release period, and can be used as slow-release nutrients for crops with a moderate growth cycle. The activity of the vitreous body containing potassium silicon is relatively low, and a stronger weak acid is required to release nutrients. The presence of the vitreous body containing potassium silicon will also delay the release of nutrients from other substances and extend the release period, making it suitable for crops with a longer growth cycle. In the present invention, the effective K2O content of the silicon-based slow-release potassium fertilizer is 10% to 40%, the effective CaO is 0% to 30%, the effective MgO is 0% to 15%, and the effective SiO2 is 20% to 40%.

[0109] Therefore, according to the slow-release characteristics of the active substances contained therein, the silicon-based slow-release potassium fertilizer of the present invention may include a combination of different active substances, for example:

[0110] In some embodiments, the silicon-based slow-release potash fertilizer of the present invention comprises (a) KAlSiO4 crystals and (b) a compound selected from K2CaSiO4, K2Ca2Si2O7, K2MgSiO4, CaMgSiO4, Ca 1.7Mg 0.3 At least one crystal of SiO4.

[0111] In some embodiments, the silicon-based slow-release potash fertilizer of the present invention comprises (a) KAlSiO4 crystals, (b) a potassium carbonate selected from K2CaSiO4, K2MgSiO4, K2Ca2Si2O7, CaMgSiO4, Ca 1.7 Mg 0.3 At least one of SiO4 crystals and a glass containing potassium silicon.

[0112] In the above embodiment, the Mol (R x The ratio of Mol(O) / Mol(SiO2) is preferably between 1.10 and 1.50, and more preferably between 1.20 and 1.40. Therefore, when manufacturing silicon-based slow-release potash fertilizer, the molar number of metal oxides in the mixed raw material Mol(R x The ratio of the molar number of SiO2 to SiO2 is preferably between 1.10 and 1.50, and more preferably between 1.20 and 1.40. The silicon-based slow-release potassium fertilizer prepared in this way has a K2O content of 25-40%, a CaO content of 0-30%, a MgO content of 0-15%, and a SiO2 content of 20-40%. The nutrient release is very fast, and it is suitable for crops with a short growth cycle or a large potassium requirement. The presence of potassium-silicon-containing glass in the combination can appropriately slow down the nutrient release rate and extend the nutrient release cycle.

[0113] In some embodiments, the silicon-based slow-release potassium fertilizer of the present invention comprises (a) KAlSiO4 crystals and (b) a compound selected from KFeSiO4, K 1.11 Fe 1.11 Si 0.89 O4, K 1.14 Mg 0.57 Si 1.43 At least one crystal of O4.

[0114] In some embodiments, the silicon-based slow-release potash fertilizer of the present invention comprises (a) KAlSiO4 crystals, (b) a compound selected from KFeSiO4, K 1.11 Fe 1.11 Si 0.89 O4, K 1.14 Mg 0.57 Si 1.43 At least one crystal of O4 and a glass containing potassium silicon.

[0115] In the above embodiment, the Mol (R xThe ratio of Mol(O) / Mol(SiO2) is preferably between 0.90 and 1.20, and more preferably between 1.00 and 1.10. Therefore, when manufacturing silicon-based slow-release potash fertilizer, the molar number of metal oxides in the mixed raw material Mol(R x The ratio of the molar number of SiO2 to the molar number of SiO2 is preferably between 0.90 and 1.20, and more preferably between 1.00 and 1.10. The silicon-based slow-release potassium fertilizer prepared in this way has a K2O content of 20 to 35%, a CaO content of 0 to 10%, a MgO content of 0 to 10%, and a SiO2 content of 25 to 40%. The nutrient release is fast and suitable for crops with a moderate growth cycle. The presence of potassium-silicon-containing glass in the combination can appropriately slow down the nutrient release rate and extend the nutrient release cycle.

[0116] In some embodiments, the silicon-based slow-release potash fertilizer of the present invention comprises (a) KAlSiO4 crystals and (b) at least one crystal selected from CaSiO3, Ca3Si3O9, Ca3Si2O7, and Ca2MgSi2O7.

[0117] In some embodiments, the silicon-based slow-release potash fertilizer of the present invention comprises (a) KAlSiO4 crystals, (b) at least one crystal selected from CaSiO3, Ca3Si3O9, Ca3Si2O7, Ca2MgSi2O7, and a glass containing silicon potassium.

[0118] In the above embodiment, the Mol (R x The ratio of Mol(O) / Mol(SiO2) is preferably between 0.80 and 1.10, and more preferably between 0.90 and 1.00. Therefore, when manufacturing silicon-based slow-release potash fertilizer, the molar number of metal oxides in the mixed raw material Mol(R x The ratio of the molar number of SiO2 to SiO2 is preferably between 0.80 and 1.10, and more preferably between 0.90 and 1.00. The silicon-based slow-release potassium fertilizer prepared in this way has a K2O content of 10 to 30%, a CaO content of 15 to 30%, a MgO content of 0 to 15%, and a SiO2 content of 20 to 40%. The nutrient release is slow, and it is suitable for crops with a long growth cycle or a small potassium requirement. The presence of potassium-silicon-containing glass in the combination can appropriately slow down the nutrient release rate and extend the nutrient release cycle.

[0119] It can be seen that the silicon-based slow-release potassium fertilizer manufactured by the present invention can control the generation and combination of potassium-containing active substances in the reaction product by changing the raw materials, proportions and process conditions, thereby achieving the control of the nutrient types, nutrient content, nutrient release rate and release period of the slow-release potassium fertilizer. The combination of KAlSiO4 and different potassium-containing active minerals will also affect its own nutrient release law, because KAlSiO4 and potassium-containing active substances have the phenomenon of mutual intersection and wrapping in microstructure. When KAlSiO4 is combined with minerals with higher activity such as K2CaSiO4, K2MgSiO4, K2Ca2Si2O7, CaMgSiO4, Ca 1.7 Mg 0.3 When KAlSiO4 coexists with SiO4, the rapid release of these minerals will inevitably cause KAlSiO4 to be exposed to the environment faster, thereby accelerating the nutrient release rate; when KAlSiO4 coexists with less active substances such as potassium-silicon-containing glass, the nutrient release rate will be slowed down due to the encapsulation or barrier of the glass.

[0120] The silicon-based slow-release potassium fertilizer of the present invention also includes other nutrient components and / or difficult-to-decompose impurity components. Those skilled in the art should understand that the raw materials such as potassium-containing materials, iron-containing materials, aluminum-containing materials, calcium-containing materials and magnesium-containing materials used to prepare the silicon-based slow-release potassium fertilizer of the present invention come from natural rock resources, industrial crude raw material products, etc., which inevitably contain impurity components that are difficult to accurately measure and determine the chemical composition. These impurity components contain, for example, but not limited to, elements such as iron, manganese, sodium, aluminum, titanium, phosphorus, boron, and zinc. After the heating process in the preparation method of the present invention, these impurity components are converted into the other nutrient components that can be absorbed and utilized by crops and / or the difficult-to-decompose impurity components that cannot be absorbed and utilized by crops. Therefore, in the present invention, the other nutrient components refer to nutrient components that can be absorbed and utilized by crops, such as, but not limited to, elements such as iron, manganese, sodium, aluminum, titanium, phosphorus, boron, and zinc, in addition to the above-mentioned crystal components and the glass component containing potassium silicon. Among them, elements such as iron, manganese, sodium, phosphorus, boron, zinc, etc., which are less in content in the silicon-based slow-release potassium fertilizer of the present invention, are also required for crop growth. For example, aluminum-containing and silicon-containing components can be converted into aluminum-silicon colloidal substances in the soil, which improve soil properties, increase soil CEC value, and improve water and fertilizer retention. In some embodiments, in the silicon-based slow-release potassium fertilizer of the present invention, the effective content of the other nutrient components, such as but not limited to the oxides of iron, manganese, sodium, aluminum, boron, zinc, etc. contained therein, is 0 to 35% by weight, preferably 0 to 25% by weight, more preferably 0 to 15% by weight, and most preferably 0 to 5% by weight, based on the total weight of the silicon-based slow-release potassium fertilizer.

[0121] In the present invention, the difficult-to-decompose impurity component refers to the difficult-to-decompose substances contained in raw materials such as potassium-containing materials, iron-containing materials, aluminum-containing materials, calcium-containing materials and magnesium-containing materials, or the difficult-to-decompose substances generated during the heating process. The difficult-to-decompose impurity components cannot be absorbed and utilized by crops. Those skilled in the art should understand that due to the complex composition of the raw materials used in the present invention, the specific chemical composition of the difficult-to-decompose substances contained therein and the difficult-to-decompose substances generated during the heating process is difficult to determine, but it cannot be absorbed and utilized by crops and cannot be used as an effective ingredient in fertilizers. Therefore, the determination of its chemical composition is not the focus of the present invention. In some embodiments, in the silicon-based slow-release potash fertilizer of the present invention, the effective content of the difficult-to-decompose impurity component in the form of oxides is 0 to 35% by weight, preferably 0 to 25% by weight, more preferably 0 to 15% by weight, and most preferably 0 to 5% by weight, based on the total weight of the silicon-based slow-release potash fertilizer.

[0122] When applied in agriculture, it is not easy to characterize the composition and proportion of active potassium-containing substances in silicon-based slow-release potassium fertilizers through phase identification. In this case, the extraction method widely used in agriculture is used to indirectly characterize the composition and proportion of silicon-based slow-release potassium fertilizers, and also indirectly characterize the nutrient release efficiency and release period of silicon-based slow-release potassium fertilizers: the nutrient content of silicon-based slow-release potassium fertilizers is extracted with three strengths of extractants, namely boiling water, 2% citric acid solution and 0.5 mol / L hydrochloric acid solution. Boiling water extraction method: weigh 2g of silicon-based slow-release potassium fertilizer powder (grind the powder or granular product to pass through a 200-mesh sieve), pour it into a 500mL beaker, add 200mL of deionized water to the beaker, place the beaker on an experimental electric furnace and heat it to boil for 15 minutes, remove the beaker from the electric furnace, and after the beaker cools to room temperature, transfer all the materials in the beaker to a 250mL volumetric flask, adjust the volume, shake well, dry filter, and detect the K2O content in the filtrate. The hot water-soluble K2O content W of the silicon-based slow-release potassium fertilizer can be obtained. K2O .W K2O Indirectly characterizes the content of hydrolyzable substances in the silicon-based slow-release potash fertilizer, that is, the relative content of substances that can quickly release nutrients. K2O The content is 0 to 8.0%, preferably 0 to 6.0%, more preferably 0 to 4.0%, and most preferably 0 to 2.0%.

[0123] In the present invention, an activity factor is introduced to characterize the composition and structure of active substances in silicon-based slow-release potassium fertilizer. The term "activity factor" (in the present invention, it can also be represented by α) refers to the K2O content C leached from silicon-based slow-release potassium fertilizer using 2% citric acid solution. K2O Compared with the K2O content extracted from silicon-based slow-release potash fertilizer using 0.5 mol / L hydrochloric acid solution K2O The ratio of α = C K2O / H K2O. Among them, C K2O The extraction method is as follows: weigh 1.0g of silicon-based slow-release potassium fertilizer powder (grind the powder or granular product to pass through a 200-mesh sieve), pour it into a 250mL stoppered conical flask, add 150mL of 2% citric acid solution preheated to 30°C into the conical flask, plug the bottle tightly, and shake well. Place the conical flask in a water bath constant temperature oscillation box and oscillate at 28-30°C for 60 minutes, dry filter, and detect the K2O content in the filtrate, thereby obtaining the C content of the silicon-based slow-release potassium fertilizer. K2O ;H K2O The extraction method is as follows: weigh 1.0g of silicon-based slow-release potassium fertilizer powder (grind the powder or granular product to pass through a 200-mesh sieve), pour it into a 250mL stoppered conical flask, add 150mL of 0.5mol / L hydrochloric acid solution preheated to 30°C into the conical flask, plug the bottle tightly, and shake well. Place the conical flask in a water bath constant temperature oscillation box and oscillate at 28-30°C for 60 minutes, dry filter, and detect the K2O content in the filtrate. From this, the H content of the silicon-based slow-release potassium fertilizer can be obtained. K2O .

[0124] The product of the present invention contains KAlSiO4, KFeSiO4, K 1.11 Fe 1.11 Si 0.89 O4, K2CaSiO4, K2Ca2Si2O7, K 1.14 Mg 0.57 Si 1.43 O4, K2MgSiO4, Ca3Si2O7, CaSiO3, Ca3(Si3O9), Ca2MgSiO7, CaMgSiO4, Ca 1.7 Mg 0.3 SiO4 crystals, potassium-containing glass and other potassium-containing active substances have different properties, such as their solubility in weak acid solutions. Therefore, their different combinations and / or different microstructures (such as interpenetration or encapsulation) will affect the final release performance of silicon-based slow-release potassium fertilizer nutrients. K2O The effective K2O content of the silicon-based slow-release potassium fertilizer is characterized. The effective nutrients in the potassium-containing active substance of the present invention can be extracted by 0.5 mol / L hydrochloric acid solution; while the C2O content obtained by leaching with a weaker 2% citric acid solution is K2O It is the relative effective K2O content of silicon-based slow-release potassium fertilizer. Not all potassium-containing active substances can be leached out by 2% citric acid solution using the above leaching method. For example, the weakly active potassium-containing silicon glassy substances are not easily leached out by 2% citric acid solution using the above leaching method. K2O The closer to H K2O, that is, the closer the "activity factor" α is to 1, the less active substances in the potassium-containing active substances in the silicon-based slow-release potassium fertilizer are, or the weaker active substances have a weaker effect on the more active substances (such as less interlacing or encapsulation between the two), which is reflected in the performance of the silicon-based slow-release potassium fertilizer, that is, the nutrient release is faster and the release period is shorter. In the silicon-based slow-release potassium fertilizer of the present invention, the activity factor is 0 to 1.0, preferably 0.2 to 1.0, more preferably 0.4 to 1.0, and most preferably 0.5 to 1.0.

[0125] The silicon-based slow-release potassium fertilizer of the present invention has the high nutrient content of water-soluble potassium fertilizers, while avoiding the shortcomings of low utilization rate and residual base ions, thus filling a gap in the field of potassium fertilizers and their agricultural applications. Compared with water-soluble potassium fertilizers, the silicon-based slow-release potassium fertilizer of the present invention is more suitable for use as base fertilizer or early topdressing. The growing season of plants is relatively long, and water-soluble fertilizers can only be guaranteed not to be deficient through multiple fertilizations, which increases labor; however, the silicon-based slow-release potassium fertilizer of the present invention will not have these phenomena at all. It is like a nutrient storage depot, which continuously and stably supplies nutrients to crops during the growing season of crops, and can achieve one-time fertilization with less or no topdressing, saving labor.

[0126] After the silicon-based slow-release potassium fertilizer of the present invention is applied to the soil, the plant mainly obtains its nutrients through two ways. The first is a passive type. Since the potassium-containing active substances in the composition of the silicon-based slow-release potassium fertilizer are soluble in weak acids, they can also be dissolved by the organic acids secreted by the plant roots, so that the nutrients are released and absorbed and utilized by the plants. In the peak season for plant fertilizer demand, the demand for nutrients is high, the types and quantities of root acids secreted are large, and the nutrient release amount of the silicon-based slow-release potassium fertilizer is also large; on the contrary, the less, the nutrients continue to be stored in the fertilizer particles. Thus, a set of on-demand release mechanisms are formed between the silicon-based slow-release potassium fertilizer and the plant. The second is active release. The potassium-containing active substances in the silicon-based slow-release potassium fertilizer are slowly released or hydrolyzed in water. The soil solution is generally acidic due to the influence of root acids, organic matter, acidogenic ions, etc., which greatly accelerates the release process of these potassium-containing active substances, and the influence of high temperature and rain accelerates this process. Therefore, the silicon-based slow-release potassium fertilizer of the present invention can adjust the nutrient release cycle of the product according to the combination and structure of different potassium-containing active minerals to adapt to the nutrient demand characteristics of different regions, different climates, and different crops.

[0127] The silicon-based slow-release potassium fertilizer of the present invention has the following advantages: (1) In addition to potassium nutrients, the silicon-based slow-release potassium fertilizer of the present invention can also provide nutrients such as calcium, magnesium, and silicon, and the nutrients are stably and continuously supplied; (2) The silicon-based slow-release potassium fertilizer of the present invention controls the nutrient release period by changing the composition and structure of different active substances, so as to be suitable for crops in the corresponding growing season or occasions where the release period is required; (3) Compared with existing water-soluble potassium fertilizers, the silicon-based slow-release potassium fertilizer of the present invention has a lower leaching rate, a higher nutrient utilization rate, no seedling burning phenomenon, and can achieve one-time fertilization with less or no topdressing, thereby reducing labor costs. ; (4) Compared with encapsulated slow-release potassium fertilizers, the silicon-based slow-release potassium fertilizer of the present invention can be used as a nutrient reserve. The nutrients are released according to the needs of crops. The more nutrients the crops need, the more nutrients the silicon-based slow-release potassium fertilizer releases. Moreover, there is no residual nutrient after the silicon-based slow-release potassium fertilizer is released. Instead, it can increase the amount of clay minerals in the soil and improve the soil properties. (5) The silicon-based slow-release potassium fertilizer of the present invention does not contain acidogenic factors such as chlorine, will not harm the soil, and can also adjust the acid-base balance of the soil, improve barrier soil, and enhance the nutrient storage capacity of the soil. The silicon-based slow-release potassium fertilizer is also a soil conditioner.

[0128] The silicon-based slow-release potash fertilizer of the present invention can be prepared by a method comprising the following steps:

[0129] (1) Raw material preparation: A potassium-containing material, at least one material selected from the group consisting of iron-containing, aluminum-containing, calcium-containing and magnesium-containing materials, and at least one compound selected from the group consisting of potassium carbonate and potassium hydroxide are mixed to prepare a raw material.

[0130] In the present invention, the potassium-containing material is a potassium-containing aluminosilicate material, including but not limited to syenite, potassium-rich shale, potassium-rich slate, potassium-rich phonolite, leucite (KAlSi2O6) or mica (H2KAl3(SiO4)3) and mixtures thereof.

[0131] In the present invention, the iron-containing materials include iron ore, magnetite, specularite and materials rich in Fe2O3 or FeO; the aluminum-containing materials include bauxite and industrial by-products containing Al2O3 or Al(OH)3; the potassium-containing materials include limestone, quicklime, slaked lime and carbide slag, etc.; the magnesium-containing materials include magnesite, brucite, dolomite, etc.

[0132] The proportion of the components in the raw material is expressed in the form of the molar ratio of the corresponding oxides, that is, the raw material proportion of the present invention is required to satisfy the R x The molar ratio of O / SiO2 is Mol(R x O) / Mol(SiO2) is between 0.50 and 2.00, preferably between 0.80 and 1.50, wherein Mol(R xR (O) represents the sum of the molar numbers of metal oxides present in the mixed raw meal, wherein the metal oxides include but are not limited to K2O, Na2O, Al2O3, Fe2O3, CaO and MgO. Since the main oxides K2O, Na2O, Al2O3, Fe2O3, CaO, MgO, SiO2 and other oxides in the mixed raw meal hardly volatilize during the processing, this also means that R in the clinker or product x The molar ratio of O / SiO2 is between 0.50 and 2.00, preferably between 0.80 and 1.50.

[0133] R in mixed raw meal x The molar ratio of O / SiO2 is Mol(R x Mol(O) / Mol(SiO2) is calculated by methods known in the art, for example, by the following formula:

[0134]

[0135] m refers to the total unit weight of a metal oxide (shown in brackets) in the mixed raw material, and M refers to the molar mass of the metal oxide.

[0136] The metal oxides in the mixed raw materials, such as K2O, are calculated by the formula of total mass per unit batch m(K2O):

[0137] m(K2O)=w A (K2O)%*a+w B (K2O)%*b+w C (K2O)%*c……

[0138] w A (K2O)% refers to the mass fraction of K2O in raw material A, a is the unit batching mass of raw material A; w B (K2O)% refers to the mass fraction of K2O in raw material B, b is the unit batching mass of raw material B; w C (K2O)% refers to the mass fraction of K2O in raw material C, c is the unit batching mass of raw material C, and so on, the total batching mass of K2O in all raw materials can be calculated. The calculation formula for the total batching mass of K2O for other metal oxides is referred to. It should be understood that the “R x O” is a general term for various metal oxides present in the mixed raw material, and may represent oxides selected from K2O, Na2O, Al2O3, Fe2O3, CaO or MgO, but is not limited thereto.

[0139] (2) Raw material heating: placing the prepared raw material in a temperature range of 900 to 1300° C. for 15 to 180 minutes to prepare the raw material.

[0140] In the present invention, the heating temperature is in the range of 900-1300° C., preferably in the range of 900-1250° C., such as 950° C., 1000° C., 1050° C., 1100° C., 1150° C. and 1200° C., etc. The heating time is in the range of 15-180 minutes, preferably 30-180 minutes, such as 45 minutes, 60 minutes, 75 minutes, 90 minutes, 105 minutes, 120 minutes, 135 minutes, 150 minutes and 165 minutes, etc. The raw material can be heated according to the conventional methods used in the art, such as using a rotary kiln, a tunnel kiln, a shuttle kiln, a box-type electric furnace, etc.

[0141] (3) Clinker processing: The clinker is cooled and then crushed to obtain silicon-based slow-release potash fertilizer.

[0142] In the present invention, the clinker can be cooled by conventional methods in the art, such as natural cooling or air cooling, until the clinker is stably cooled to below room temperature + 90°C, preferably below room temperature + 65°C, and most preferably below room temperature + 40°C.

[0143] After the clinker is cooled to a suitable temperature, it is crushed and ground by conventional methods in the art, for example, using a ball mill or a Raymond mill (such as the model 4R3216 mill produced by Henan Liming Heavy Industry Technology Co., Ltd.) to grind the clinker into a powdery product, or granulate it, for example, using a double-roll granulator or a disc ball machine or a rotary granulator to make a granular product with the help of a binder, or directly crush the clinker into particles of a desired particle size.

[0144] Compared with the existing method for processing potassium-containing rocks, the method for producing slow-release potassium fertilizer of the present invention has the advantages of different target products, reduced dosage of auxiliary agents, lower energy consumption and high nutrient content of the product; compared with the high-temperature melting quenching method, the temperature of the present invention is relatively low, and the product does not produce melting phenomenon, the operation is simple, and the corrosion problem of the alkaline material on the equipment container during melting is avoided; the potassium-containing rock is used as the main raw material to produce potassium fertilizer, the production cost of the product is greatly reduced, and it is suitable for large-scale promotion and application.

[0145] Example 1

[0146] Table 3. Raw material composition analysis table used in Example 1

[0147] name <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> MgO CaO <![CDATA[Na2O]]> <![CDATA[K2O]]> Potash feldspar powder 61.30 16.99 2.84 0.5 0.5 1.32 13.37 Dolomite powder 0.20 0.07 0.21 21.03 31.08 0.05 0.01

[0148] Note: All data in the table are weight percentages.

[0149] Weigh 1000g of feldspar powder, 450g of dolomite powder and 50g of potassium carbonate, and add 300g of 48% potassium hydroxide solution, stir the prepared raw material evenly, and the R xThe O / SiO2 ratio was 0.95. The uniformly mixed raw materials were placed in a box-type electric furnace and calcined at 1150°C for 30 minutes. After cooling, they were ground to obtain 1370g of silicon-based slow-release potassium fertilizer K-1. X-ray powder diffraction analysis of K-1 was performed (the results are shown in Figure 1 ), and compared the diffraction peak position in the figure with the standard card, it was concluded that the crystal material composition of product K-1 is mainly KAlSiO4 and Ca2MgSi2O7, and the appearance of bulges in the diffraction spectrum indicates the production of vitreous material. In order to determine the composition of vitreous material, K-1 was leached with a slightly excess of 2% citric acid solution and 0.5 mol / L hydrochloric acid solution (leaching conditions: oscillation in a water bath constant temperature oscillation box at 28°C for 60 minutes), the leached residue was filtered, washed and dried, and the leached residue was subjected to component analysis and phase analysis. The component analysis results are shown in the table below.

[0150] Table 4. Composition analysis results of the leached residue of Example 1

[0151] name <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> MgO CaO <![CDATA[Na2O]]> <![CDATA[K2O]]> 2% citric acid extraction residue 57.85 5.19 1.59 4.27 5.09 1.18 12.1 0.5mol / L hydrochloric acid leaching residue 83.6 1.12 0.88 0.42 0.37 0.33 0.56

[0152] Note: All data in the table are weight percentages.

[0153] After K-1 was leached with 0.5 mol / L hydrochloric acid, the cation contents of K2O, MgO and CaO in the leached residue were very low, indicating that the effective nutrients had been leached out; while after K-1 was leached with 2% citric acid solution, some nutrients still existed in the leached residue (mainly containing potassium and silicon), and XRD analysis of the leached residue confirmed that there was no crystalline substance in it, indicating that the potassium-silicon-containing substance retained in the leached residue was glass. In addition to KAlSiO4 and Ca2MgSi2O7, the corresponding product K-1 also contained potassium-silicon glass. The activity of the potassium-silicon glass was weak, and a stronger hydrochloric acid was needed to leach out the potassium nutrient.

[0154] Various extractions were carried out on silicon-based slow-release potassium fertilizer K-1 and the components of the extracts were analyzed, as shown in the table below.

[0155] Table 5. Component analysis results of the extract of Example 1

[0156] Serial number Extraction agent <![CDATA[K2O(%)]]> <![CDATA[SiO2(%)]]> CaO(%) MgO(%) 1 0.5mol / L HCl 20.55 28.96 9.23 7.20 2 2% citric acid 14.68 22.65 7.90 6.2 3 Boiling water 0.77 / / / 4 20% acid equivalent 0.5mol / L HCl 4.32 / / / 5 40% acid equivalent 0.5mol / L HCl 9.95 / / / 6 60% acid equivalent 0.5mol / L HCl 15.81 / / / 7 80% acid equivalent 0.5mol / L HCl 18.67 / / /

[0157] Note: All data in the table are weight percentages.

[0158] Note: The test conditions of the above groups are: No. 1-3 is 1.0g silicon-based slow-release potassium fertilizer extracted with 150mL of extractant,

[0159] No. 1-2 is to oscillate in a water bath constant temperature oscillating box at 28℃-30℃ for 60min, and No. 3 is to heat

[0160] Boil for 15 minutes. The acid equivalent of No. 4 to No. 7 refers to the amount of cations in the product calculated based on the raw material ratio.

[0161] The amount of acid required for the total amount of ions is determined by the experimental conditions of 28°C-30°C in a water bath constant temperature oscillating box.

[0162] Oscillate for 60 min.

[0163] It can be seen from the above experimental data that the silicon-based slow-release potash fertilizer K-1 prepared by the present invention has a hot water-soluble K2O content of less than 1%, a 2% citric acid leaching K2O of 14.68%, an effective K2O of 20.55%, an activity factor of 0.71, and a relatively weak activity. The effective SiO2 is 28.96%, the effective CaO is 9.23%, and the effective MgO is 7.20% (the effective oxide content here refers to the content of the oxide leached with 0.5 mol / L HCl, and the specific leaching method has been described above, the same below). The potassium-silicon-containing glass body in the silicon-based slow-release potash fertilizer K-1 has a low nutrient release rate itself, and hinders the decomposition and release of KAlSiO4 and Ca2MgSi2O7. Therefore, the overall nutrient release of the silicon-based slow-release potash fertilizer K-1 is slow and the release period is long.

[0164] Silicon-based slow-release potassium fertilizer K-1 was extracted with dilute hydrochloric acid with an acid equivalent of 20%, 40%, 60% and 80%, and the effective K2O extracted was 4.32%, 9.95%, 15.81% and 18.67%, respectively, indicating that the silicon-based slow-release potassium fertilizer releases more nutrients with the increase of acid amount, that is, when the plant needs nutrients and secretes organic acid, the silicon-based slow-release potassium fertilizer will control the release according to the amount of acid secreted by the plant. When the nutrient demand is strong, the root acid secretion is large, and the slow-release potassium fertilizer releases more nutrients; when the nutrient demand is weak, the root acid secretion is small, the nutrients released are small and stored in the silicon-based slow-release fertilizer particles, thereby achieving the purpose of slow and controlled release.

[0165] Example 2

[0166] Table 6. Analysis of raw materials used in Example 2

[0167] name <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> MgO CaO <![CDATA[Na2O]]> <![CDATA[K2O]]> Nepheline syenite 54.68 20.26 4.78 0.8 1.29 0.45 13.19

[0168] Note: All data in the table are mass percentages.

[0169] Weigh 1000g of nepheline syenite powder (in nepheline syenite, the KAlSi3O8 content is usually ≥60% or the K2O content is ≥10%), 400g of calcium carbonate powder and 520g of potassium carbonate, and stir the prepared raw material evenly. x The O / SiO2 ratio is 1.31. The evenly stirred raw material is placed in a box-type electric furnace and calcined at 900°C for 60 minutes. After the material is naturally cooled, it is ground to obtain 1540g of silicon-based slow-release potash fertilizer product K-2.

[0170] X-ray powder diffraction analysis was performed on K-2 (results are shown in Figure 2 ), its main components are KAlSiO4 and K2CaSiO4. The presence of amorphous bulges in the spectrum indicates the presence of vitreous substances. K-2 was subjected to various leaching operations and the components of the leaching solution were analyzed. The results are shown in the table below.

[0171] Table 7. Component analysis results of the extract of Example 2

[0172] Serial number Extraction agent <![CDATA[K2O(%)]]> <![CDATA[SiO2(%)]]> CaO(%) MgO(%) 1 0.5mol / L HCl 31.36 35.02 15.02 0.26 2 2% citric acid 31.08 34.95 15.02 0.22 3 Boiling water 8.20 / / /

[0173] Note: All data in the table are mass percentages.

[0174] As can be known from the above experimental data, the silicon-based slow-release potash fertilizer K-2 prepared by the present invention consists of KAlSiO4, K2CaSiO4 and vitreous substances. K2CaSiO4 is a highly active substance, which is easy to decompose and release nutrients in the environment, and then KAlSiO4 is quickly exposed to the environment with nano-scale particle size, thereby shortening the release period of the silicon-based slow-release potash fertilizer K-2. The K2O content of K-2 boiling water extraction reaches 8.20%, and the activity factor is 1.0, which is highly active and has a short release period. The effective SiO2 of the silicon-based slow-release potash fertilizer K-2 is 35.02%, the effective CaO is 15.02%, and the effective MgO is 0.26%.

[0175] Example 3

[0176] Weigh 1000g of potassium phonolite powder (with potassium feldspar as the main mineral component, usually KAlSi3O8 content ≥60% or K2O content ≥10%), 72g of quicklime, 98g of magnesite powder (with MgCO3 as the main mineral component), 160g of iron ore powder, 165g of potassium carbonate and 400g of 48% potassium hydroxide solution, stir the prepared raw materials evenly, and the R x The O / SiO2 ratio is 1.03. The evenly stirred raw material is placed in a box-type electric furnace and calcined at 1000°C for 120 minutes. After the material is cooled, it is ground to obtain 1500g of silicon-based slow-release potash fertilizer product K-3.

[0177] X-ray powder diffraction analysis of K-3 (see Figure 3 ), whose material composition is mainly KAlSiO4, K 1.11 Fe 1.11 Si 0.89 O4. K-3 was subjected to various leaching operations and the components of the leaching solution were analyzed, as shown in the table below.

[0178] Table 8. Component analysis results of the extract of Example 3

[0179]

[0180]

[0181] Note: All data in the table are mass percentages.

[0182] From the above experimental data, it can be seen that the slow-release potash fertilizer K-3 prepared by the present invention has a material composition of KAlSiO4, K 1.11 Fe 1.11 Si 0.89 O4, the K2O content of boiling water extraction reaches 1.02%, the K2O content of 2% citric acid solution extraction is 25.82%, the effective K2O is 26.51%, the activity factor is 0.97, the activity is strong, and the release period is short. The effective SiO2 of silicon-based slow-release potash fertilizer is 35.56%, the effective CaO is 4.21%, and the effective MgO is 3.06%.

[0183] Example 4

[0184] Weigh 1000g of potassium-rich shale powder (in potassium-rich shale, the KAlSi3O8 content is usually ≥60% or the K2O content is ≥10%), 340g of aluminum hydroxide powder calcined at 900°C, and 240g of potassium carbonate in a mixer, and stir them. At the same time, add 400g of 48% potassium hydroxide liquid. x The O / SiO2 is 1.08. The uniformly mixed raw material is placed in a box-type electric furnace and heated at 1000°C for 180 minutes. After the material is cooled, it is taken out and ground to obtain 1630g of product K-4.

[0185] X-ray powder diffraction analysis of K-4 (see Figure 4 ), its crystal material is KAlSiO4 after comparative analysis, and there are amorphous bulges in the spectrum, which should be vitreous material containing potassium silicon. K-4 was subjected to various leaching and analysis, as shown in the table below.

[0186] Table 9. Component analysis results of the extract of Example 4

[0187] Serial number test <![CDATA[K2O(%)]]> <![CDATA[SiO2(%)]]> CaO(%) MgO(%) 1 0.5mol / L HCl 25.37 30.24 0.52 0.26 2 2% citric acid 23.25 29.88 0.46 0.15 3 Boiling water 0.95 / / /

[0188] Note: All data in the table are mass percentages.

[0189] It can be seen from the above experimental data that the slow-release potash fertilizer K-4 prepared by the present invention mainly consists of KAlSiO4 and potassium-containing silicon glassy substances, which are interlaced with each other. The presence of potassium-containing glassy substances affects the nutrient release of KAlSiO4. The K2O content of boiling water extraction is 0.95%, the K2O of 2% citric acid solution extraction is 23.25%, the effective K2O is 25.37%, the activity factor is 0.92, the effective SiO2 is 30.24%, the effective CaO is 0.52%, and the effective MgO is 0.26%.

[0190] Example 5

[0191] Table 10. Raw material composition analysis table used in Example 5

[0192] name <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> MgO CaO <![CDATA[Na2O]]> <![CDATA[K2O]]> Potassium feldspar 61.30 16.99 2.84 0.5 0.5 1.32 13.37

[0193] Note: All data in the table are weight percentages.

[0194] Weigh 1000g of potassium feldspar powder, 400g of calcium carbonate powder and 370g of 48% KOH solution, mix well, and the R of the raw material x The O / SiO2 ratio is 0.9. The uniformly mixed raw material is placed in a box-type electric furnace and kept warm at 1100°C for 60 minutes. After the material is cooled, it is taken out and ground to obtain 1350g of product K-5.

[0195] X-ray powder diffraction analysis of K-5 (see Figure 5 ), the obtained spectrum was compared with the standard card and analyzed to conclude that the crystalline substances in K-5 are mainly KAlSiO4, CaSiO3 and Ca3(Si3O9), and the amorphous bulge shows that there is also vitreous substance. In order to determine the composition of vitreous substance, K-5 was leached with a slightly excess of 2% citric acid solution and 0.5mol / L hydrochloric acid solution (leaching conditions: oscillation in a water bath constant temperature oscillation box at 28°C for 60 minutes), the leached residue was filtered, washed and dried, and the leached residue was analyzed for composition and phase, and the results are shown in the table below.

[0196] Table 11. Composition analysis and phase analysis results of the leached residue of Example 5

[0197] name <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> MgO CaO <![CDATA[Na2O]]> <![CDATA[K2O]]> 2% citric acid extraction residue 62.93 7.42 1.84 0.21 6.09 0.78 13.51 0.5mol / L hydrochloric acid leaching residue 84.6 0.43 0.25 0.01 0.16 0.01 0.08

[0198] Note: All data in the table are weight percentages.

[0199] From the above experimental data, it can be seen that after K-5 was leached with 0.5mol / L hydrochloric acid, all the effective nutrients were leached out, and after K-5 was leached with 2% citric acid solution, some nutrients still existed in the leaching residue. After XRD analysis of the leaching residue, it was confirmed that there was no crystalline substance in it, indicating that the potassium-silicon-containing substance retained in the leaching residue was glass. In addition to KAlSiO4, CaSiO3 and Ca3(Si3O9), the corresponding product K-5 also contained potassium-silicon-containing glass.

[0200] K-5 was subjected to various extractions and the components of the extracts were analyzed, as shown in the table below.

[0201] Table 12. Component analysis results of the extract of Example 5

[0202] Serial number test <![CDATA[K2O]]> <![CDATA[SiO2]]> CaO MgO 1 0.5mol / L HCl 20.59 30.28 15.82 0.26 2 2% citric acid 17.08 24.85 12.95 0.08 3 Boiling water 0.58 / / /

[0203] Note: All data in the table are weight percentages.

[0204] It can be seen from the above experimental data that the slow-release potash fertilizer K-5 prepared by the present invention mainly consists of KAlSiO4, CaSiO3, Ca3 (Si3O9) and potassium-silicon-containing vitreous substances, which intersect and influence each other in structure. The presence of potassium-containing vitreous substances affects the nutrient release of KAlSiO4. The K2O content extracted by boiling water is 0.58%, the K2O extracted by 2% citric acid solution is 17.08%, the effective K2O is 20.59%, the activity factor is 0.83, the effective SiO2 is 30.28%, the effective CaO is 15.82%, and the effective MgO is 0.26%.

[0205] Example 6

[0206] Weigh 1000g of nepheline syenite powder, 592g of calcium hydroxide powder and 65g of 48% KOH solution. x The O / SiO2 ratio is 1.16. After mixing evenly, keep the mixture at 1250°C in a box-type electric furnace for 60 minutes. After the material is cooled, take it out and grind it to obtain 1450g of product K-6.

[0207] X-ray powder diffraction analysis of K-6 (see Figure 6 ), the obtained spectrum was compared with the standard card, and it was concluded that the crystalline substances in K-6 were mainly KAlSiO4, CaSiO3 and Ca3Si2O7 and vitreous substances. K-6 was subjected to various leaching and the components of the leaching solution were analyzed. The results are shown in the table below.

[0208] Table 13. Component analysis results of the extract of Example 6

[0209] Serial number test <![CDATA[K2O(%)]]> <![CDATA[SiO2(%)]]> CaO(%) MgO(%) 1 0.5mol / L HCl 10.91 35.56 29.32 0.32 2 2% citric acid 8.51 33.85 28.22 0.15 3 Boiling water 0.0 / / /

[0210] Note: All data in the table are mass percentages.

[0211] It can be seen from the above experimental data that the slow-release potash fertilizer K-6 prepared by the present invention mainly consists of KAlSiO4, CaSiO3, Ca3Si2O7 and potassium-containing vitreous substances, which intersect and influence each other in structure. The presence of potassium-containing vitreous substances affects the nutrient release of KAlSiO4. The K2O content extracted by boiling water is 0%, the K2O extracted by 2% citric acid solution is 8.51%, the effective K2O is 10.91%, the activity factor is 0.78, the effective SiO2 is 35.56%, the effective CaO is 29.32%, and the effective MgO is 0.32%.

[0212] Example 7

[0213] 1000g of feldspar powder, 75g of brucite powder, 450g of calcium carbonate powder and 390g of 48% KOH solution were mixed evenly. x The O / SiO2 ratio is 1.27, and then the raw material is kept at 1150°C for 90 minutes. After the material is cooled, it is taken out and ground to obtain 1420g of product K-7.

[0214] K-7 was subjected to X-ray powder diffraction analysis (results are shown in Figure 7 ), whose potassium-containing active substances are mainly KAlSiO4, K 1.14 Mg 0.57 Si 1.43 O4、Ca 1.7 Mg 0.3 SiO4. K-7 was subjected to various leaching processes and the components of the leaching solutions were analyzed. The results are shown in the table below.

[0215] Table 14. Component analysis results of the extract of Example 7

[0216] Serial number test <![CDATA[K2O(%)]]> <![CDATA[SiO2(%)]]> CaO(%) MgO(%) 1 0.5mol / L HCl 19.71 32.36 18.03 4.09 2 2% citric acid 18.38 31.04 17.22 4.05 3 Boiling water 1.84 / / /

[0217] Note: All data in the table are mass percentages.

[0218] From the above experimental data, it can be seen that the slow-release potash fertilizer K-7 prepared by the present invention has a water-soluble K2O content of 1.84%, K2O extracted from 2% citric acid solution is 18.38%, effective K2O is 19.71%, activity factor is 0.93, effective SiO2 is 32.36%, effective CaO is 18.03%, and effective MgO is 4.09%.

[0219] Example 8

[0220] 1000g microcline powder, 550g basic magnesium carbonate powder, 326g carbide slag and 280g 48% KOH solution were mixed evenly. xThe O / SiO2 ratio is 1.43, and then the raw material is kept at 1150°C for 1.5 hours. After the material is cooled, it is taken out and ground to obtain 1540g of product K-8.

[0221] X-ray powder diffraction analysis of K-8 showed that its potassium-containing active substances were mainly KAlSiO4, CaMgSiO4, K 1.14 Mg 0.57 Si 1.43 O4. K-8 was subjected to various extractions and the components of the extracts were analyzed, as shown in the table below.

[0222] Table 15. Component analysis results of the extract of Example 8

[0223] Serial number test <![CDATA[K2O(%)]]> <![CDATA[SiO2(%)]]> CaO(%) MgO(%) 1 0.5mol / L HCl 15.76 38.66 13.51 14.89 2 2% citric acid 15.33 35.54 13.15 14.35 3 Boiling water 2.93 / / /

[0224] Note: All data in the table are mass percentages.

[0225] From the above experimental data, it can be seen that the slow-release potash fertilizer K-8 prepared by the present invention has a water-soluble K2O content of 2.93%, a K2O content of 15.33% extracted by 2% citric acid solution, an effective K2O content of 15.76%, an activity factor of 0.97, an effective SiO2 content of 38.66%, an effective CaO content of 13.51%, and an effective MgO content of 14.89%.

[0226] Example 9

[0227] Weigh 900g of quartz syenite powder (in quartz syenite, the KAlSi3O8 content is usually ≥60% or the K2O content is ≥10%), 100g of bauxite powder, 290g of limestone powder, 150g of brucite powder and 355g of potassium carbonate and mix them evenly. x The O / SiO2 ratio is 1.22. The uniformly mixed raw materials are kept at 1100°C for 2 hours. After cooling, they are taken out and ground to obtain 1486g of product K-9.

[0228] X-ray powder diffraction analysis of K-9 shows that its main material composition is KAlSiO4, K2Ca2Si2O7 and CaMgSiO4. Various extractions were performed on K-9 and the components of the extracts were analyzed, as shown in the table below.

[0229] Table 16. Component analysis results of the extract of Example 9

[0230] Serial number Extraction agent <![CDATA[K2O(%)]]> <![CDATA[SiO2(%)]]> CaO(%) MgO(%) 1 0.5mol / L HCl 25.36 33.65 10.50 7.62 2 2% citric acid 25.10 32.25 10.26 7.58 3 Boiling water 1.98 / / /

[0231] Note: All data in the table are mass percentages.

[0232] From the above experimental data, it can be seen that the slow-release potash fertilizer K-9 prepared by the present invention has a hot water-soluble K2O content of 1.98%, a K2O content of 25.10% extracted by 2% citric acid solution, an effective K2O content of 25.36%, an activity factor of 0.99, an effective SiO2 content of 33.65%, an effective CaO content of 10.50%, and an effective MgO content of 7.62%.

[0233] Example 10

[0234] Experiments on nutrient release rates were conducted on silicon-based slow-release potassium fertilizers K-1, K-2, K-3, K-4, K-5, K-6, K-7, K-8, and K-9. The experimental process was to continuously extract the silicon-based slow-release potassium fertilizers with an excess of citric acid-sodium citrate buffer solution with a pH of 6.0 at 25°C, and detect the amount of K2O in the supernatant at regular intervals. When the K2O detection result reached 95% of the effective K2O content of the corresponding silicon-based slow-release potassium fertilizer, the release period of the silicon-based slow-release potassium fertilizer was the continuous extraction time. The results are shown in the table below.

[0235] Table 17. Experimental results of nutrient release rate of silicon-based slow-release potassium fertilizer

[0236] Silicon-based slow-release potash fertilizer Release period / day Material composition includes K-1 100 <![CDATA[KAlSiO4, Ca2MgSi2O7 and potassium-silicon-containing glass]]> K-2 10 <![CDATA[KAlSiO4 and K2CaSiO4]]> K-3 31 <![CDATA[KAlSiO4 and K 1.11 Fe 1.11 Si 0.89 O4.]]> K-4 46 <![CDATA[KAlSiO4 and potassium-silicon-containing vitreous substances]]> K-5 82 <![CDATA[KAlSiO4, CaSiO3, Ca3(Si3O9) and potassium-containing silicon glass]]> K-6 56 <![CDATA[KAlSiO4, CaSiO3 and Ca3Si2O7]]> K-7 32 <![CDATA[KAlSiO4、K 1.14 Mg 0.57 Si 1.43 O4 and Ca 1.7 Mg 0.3 SiO4. ]]> K-8 25 <![CDATA[KAlSiO4, CaMgSiO4 and K 1.14 Mg 0.57 Si 1.43 O4]]> K-9 15 <![CDATA[KAlSiO4, K2Ca2Si2O7 and CaMgSiO4]]>

[0237] Embodiment 11

[0238] Silicon-based slow-release potassium fertilizers K-1, K-2 and K-3 were selected as the objects of field agronomic experiments. The test methods and results are shown in the table below.

[0239] Table 18. Agronomic experimental results of silicon-based slow-release potassium fertilizers

[0240]

[0241]

[0242] It can be seen from the above experimental results that the silicon-based slow-release potash fertilizer obtained according to the present invention can realize the control of the nutrient release period of the product to meet the needs of different crops and soil conditions, and compared with traditional potash fertilizers, it plays a similar or even better role in providing nutrients.

Claims

1. A silicon-based slow-release potash fertilizer comprising (a) KAlSiO4 crystals and (b) at least one substance selected from K2O-Fe2O3-SiO2 system crystals, K2O-CaO-SiO2 system crystals, K2O-MgO-SiO2 system crystals, CaO-SiO2 system crystals, CaO-MgO-SiO2 system crystals and a glass containing potassium silicon; The K2O-Fe2O3-SiO2 system crystals include KFeSiO4 crystals, K 1.11 Fe 1.11 Si 0.89 O4 crystals or mixtures thereof; The K2O-CaO-SiO2 system crystals include K2CaSiO4 crystals, K2Ca2Si2O7 crystals or a mixture thereof; The K2O-MgO-SiO2 system crystal includes K 1.14 Mg 0.57 Si 1.43 O4 crystals, K2MgSiO4 crystals or a mixture thereof; The CaO-SiO2 system crystals include Ca3Si2O7 crystals, CaSiO3 crystals, Ca3(Si3O9) crystals or a mixture thereof; The CaO-MgO-SiO2 system crystals include Ca2MgSi2O7 crystals, CaMgSiO4 crystals, Ca 1.7 Mg 0.3 SiO4 crystals or mixtures thereof; in, Based on the total weight of the silicon-based slow-release potash fertilizer, the effective K2O content is 10 to 40 weight %, the effective SiO2 content is 20 to 40 weight %, the effective CaO content is 0 to 30 weight %, and the effective MgO content is 0 to 15 weight %; The raw materials for manufacturing the silicon-based slow-release potash fertilizer include (a) a potassium-containing aluminosilicate material, (b) at least one material selected from iron-containing materials, aluminum-containing materials, calcium-containing materials and magnesium-containing materials, and (c) at least one compound selected from potassium carbonate and potassium hydroxide; The ratio of the components in the raw materials satisfies the following relationship: in the raw material obtained by combining and mixing the raw materials, the molar number Mol (R x The ratio of the molar number of the metal oxide Mol(R x O) is the sum of the moles of metal oxides present in the raw meal, wherein the metal oxides are selected from K2O, Na2O, Al2O3, Fe2O3, CaO and MgO; The silicon-based slow-release potash fertilizer is manufactured by the following steps: (1) Raw meal preparation: (a) a potassium-containing aluminosilicate material, (b) at least one material selected from the group consisting of an iron-containing material, an aluminum-containing material, a calcium-containing material and a magnesium-containing material, and (c) at least one compound selected from the group consisting of potassium carbonate and potassium hydroxide are mixed to prepare the raw meal; (2) Raw material heating: placing the prepared raw material in a temperature range of 900 to 1200° C. for 15 to 180 minutes to prepare the raw material; (3) Clinker processing: The clinker is cooled and then crushed to obtain the silicon-based slow-release potash fertilizer.

2. The silicon-based slow-release potash fertilizer according to claim 1, wherein: In the raw material, the molar number of metal oxides Mol (R x The ratio of the molar number of O) to SiO2, Mol(SiO2), is in the range of 0.80 to 1.

50.

3. The silicon-based slow-release potash fertilizer according to claim 1, wherein: In the raw material, the molar number of metal oxides Mol (R x The ratio of the molar number of O) to SiO2, Mol(SiO2), is in the range of 1.0 to 1.

1.

4. The method for producing a silicon-based slow-release potash fertilizer according to claim 1, wherein: In the raw material, the potassium-containing aluminosilicate material is selected from potassium-containing aluminosilicate ore resources or mixtures thereof with KAlSi3O8, leucite KAlSi2O6 or mica H2KAl3(SiO4)3 as the main mineral composition; the molar number of metal oxide Mol(R x The ratio of the molar number of the metal oxide Mol(R x O) is the sum of the molar numbers of metal oxides present in the raw meal, wherein the metal oxides are selected from K2O, Na2O, Al2O3, Fe2O3, CaO and MgO.

5. The method for producing a silicon-based slow-release potash fertilizer according to claim 4, wherein: In the raw material, the molar number of metal oxides Mol (R x The ratio of the molar number of O) to SiO2, Mol(SiO2), is in the range of 0.80 to 1.

50.

6. The method for producing a silicon-based slow-release potash fertilizer according to claim 4, wherein: In the raw material, the molar number of metal oxides Mol (R x The ratio of the molar number of O) to SiO2, Mol(SiO2), is in the range of 1.0 to 1.

1.

7. The silicon-based slow-release potash fertilizer according to claim 1, wherein the heating temperature is 950-1100°C and the heating time is 30-90 minutes.

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