Preparation method of diatomite filter aid

Abstract

The invention belongs to the technical field of mineral processing, and particularly relates to a preparation method of a diatomite filter aid. The preparation method of the diatomite filter aid comprises the following steps: (1) calcining diatomite raw ore to obtain primary diatomite; (2) carrying out acid leaching treatment on the first-grade diatomite, and washing the first-grade diatomite subjected to acid leaching to obtain refined diatomite; and (3) calcining the refined diatomite in an acid atmosphere to obtain the diatomite filter aid. The diatomite filter aid has the beneficial effects that the diatomite filter aid meets the requirements of United States Pharmacopoeia and Chinese Pharmacopoeia.

Description

Technical Field

[0001] The invention belongs to the technical field of mineral processing, and in particular relates to a method for preparing a diatomite filter aid. Background Art

[0002] Diatomaceous earth is a kind of diatomite deposited by the remains of diatoms, the main component of which is amorphous SiO 2 A natural porous rock whose mineral components are opal and its variants. It has a well-developed and ordered microporous structure, a large specific surface area and a small bulk density, high stability, acid resistance and heat resistance. It is widely used in the filtration of various beverages, wines, blood, pharmaceutical products, as well as pesticides, soil conditioners, animal feed, papermaking, rubber, plastics, building materials and other fields. It is an important non-metallic mineral resource.

[0003] During the filtration process, the surface of the diatomite filter aid first intercepts the impurities with large particles to form a retention layer, and then continues to intercept the impurities with similar particle sizes to this layer through this retention layer. The impurities with small particles enter the internal pores of the diatomite through the retention layer and the large pores on the surface of the filter aid, and are intercepted by the small pores inside the diatomite. Proteins, pigments and other high molecular substances with high surface activity, because their own charges are different from those of diatomite, stay in the diatomite filter cake through electrostatic adsorption or other adsorption effects. The safety of drugs, blood, etc. is a major problem facing the world today. Practical applications have proved that diatomite filter aids not only have a good removal effect on impurities with relatively large particle sizes, but also have a good effect on removing colloidal substances, bacteria and viruses. In addition, diatomite also has the advantages of low water solubility, acid solubility, colorlessness, tastelessness and chemical stability. It is not easy to react with other substances, which can improve the filtration quality and rate and reduce the filtration cost.

[0004] Diatomaceous earth filter aids are affected by the properties of the diatomaceous earth ore. The filtration efficiency and filtration accuracy are difficult to meet the requirements for the use of pharmaceutical-grade filter aids. In particular, the iron-containing mineral impurities in the diatomaceous earth filter aids will enter the filtrate in the form of iron ions during filtration, accelerating the oxidation of sugars, amino acids, polyphenols, etc., and contaminating drugs and blood. At present, there are strict regulations on pharmaceutical-grade diatomaceous earth filter aids internationally, requiring SiO 2 Content ≥90.0%, acid-soluble iron ion content, washable lead and washable arsenic content are ≤10mg / kg, endotoxin content ≤1EU / g, non-silicon content ≤25%, loss on ignition ≤2.0%, acid-soluble matter ≤2.0%, water-soluble matter ≤0.2%. Therefore, purifying diatomite ore is an effective measure to improve the performance of diatomite filter aid products.

[0005] The existing diatomite purification technologies such as calcination, acid leaching, scrubbing, flotation, and magnetic separation all have their own limitations. For example, calcination is only effective in removing organic matter from diatomite, but cannot remove other impurities; acid leaching has a good purification effect, but consumes a lot of acid and water; scrubbing and flotation are only suitable for low-grade diatomite, and the purification effect is poor; magnetic separation can only remove magnetic impurities such as magnetite from diatomite, but cannot remove other impurities. A single purification method is usually difficult to achieve the ideal purification effect. The combined purification method can give full play to their respective advantages, improve the purification effect of diatomite, and thus improve the quality of diatomite filter aids. However, the existing combined purification method has a cumbersome purification process, and the prepared diatomite filter aid SiO 2 The content is not high, and the acid-soluble iron and other indicators do not meet the standards of pharmaceutical-grade filter aids, so it can only be used for filtering beverages and alcoholic beverages. In order to meet the needs of the pharmaceutical industry, a product that can effectively improve the SiO content of diatomite has been developed. 2 The production technology of medical grade diatomaceous earth filter aid is of great significance for improving purity and reducing the content of soluble metal ions such as iron, lead, arsenic, etc. Summary of the invention

[0006] The present application provides a method for preparing a diatomite filter aid, aiming to solve the problem of the existing diatomite filter aid SiO 2 The content is low and the amount of acid-soluble iron dissolution is high, which cannot meet the requirements for the use of medical grade filter aids.

[0007] The first aspect of the present application provides a method for preparing a diatomaceous earth filter aid, comprising the following steps:

[0008] (1) calcining diatomite ore to obtain primary diatomite;

[0009] (2) subjecting the primary diatomaceous earth to an acid leaching treatment, and then washing the acid leached primary diatomaceous earth to obtain diatomaceous earth fine soil;

[0010] (3) Calcining diatomaceous earth in an acidic atmosphere to obtain the diatomaceous earth filter aid.

[0011] According to some embodiments of the method for preparing the diatomite filter aid described in the present application, the SiO 2 The mass content is 80%-85%.

[0012] According to some embodiments of the method for preparing a diatomaceous earth filter aid described in the present application, the particle size of the diatomaceous earth ore is less than or equal to 75 μm.

[0013] According to some embodiments of the method for preparing the diatomaceous earth filter aid described in the present application, the calcination temperature in step (1) is 200° C.-800° C., and the calcination time is 0.5 h-2 h.

[0014] According to some embodiments of the method for preparing the diatomaceous earth filter aid described in the present application, the heating rate during the calcination in step (1) is 0.5-20° C. / min.

[0015] According to some embodiments of the method for preparing the diatomite filter aid described in the present application, the acid leaching treatment includes mixing the primary diatomite, the acid leaching solution and the dispersant, and performing the acid leaching treatment.

[0016] According to some embodiments of the method for preparing the diatomaceous earth filter aid described in the present application, the acid leaching solution includes one or more of hydrochloric acid, sulfuric acid, nitric acid and perchloric acid.

[0017] According to some embodiments of the method for preparing the diatomaceous earth filter aid described in the present application, the dispersant includes sodium tripolyphosphate and sodium silicate.

[0018] According to some embodiments of the method for preparing the diatomite filter aid described in the present application, the dosage ratio of the primary diatomite to the acid leaching solution is 1 kg: 2 L-10 L.

[0019] According to some embodiments of the method for preparing the diatomite filter aid described in the present application, the amount of the dispersant used is 0.3%-0.5% of the mass of the primary diatomite.

[0020] According to some embodiments of the method for preparing a diatomaceous earth filter aid described in the present application, the concentration of the acid in the acid leaching solution is 1-10 mol / L.

[0021] According to some embodiments of the method for preparing the diatomaceous earth filter aid described in the present application, the mass ratio of the sodium tripolyphosphate to the sodium silicate in the dispersant is (0.8-1.2):1.

[0022] According to some embodiments of the method for preparing the diatomite filter aid described in the present application, the temperature of the acid leaching is 70-100° C., and the time of the acid leaching is 2-12 hours.

[0023] According to some embodiments of the method for preparing the diatomaceous earth filter aid described in the present application, the detergent used for washing includes deionized water, and the washing is stopped when the pH of the washing wastewater generated by washing is greater than 5.

[0024] According to some embodiments of the method for preparing the diatomite filter aid described in the present application, the water content of the diatomite refined soil is 40wt%-50wt%.

[0025] According to some embodiments of the method for preparing the diatomite filter aid described in the present application, the preparation method further comprises mixing diatomite fine soil and a flux, and then calcining.

[0026] According to some embodiments of the method for preparing the diatomaceous earth filter aid described in the present application, the acidic atmosphere includes chlorine and / or hydrogen chloride.

[0027] According to some embodiments of the method for preparing the diatomaceous earth filter aid described in the present application, the calcination temperature in step (3) is 800° C.-1200° C., and the calcination time is 0.5 h-2 h.

[0028] According to some embodiments of the method for preparing the diatomaceous earth filter aid described in the present application, the heating rate during the calcination in step (3) is 0.5-20° C. / min.

[0029] According to some embodiments of the method for preparing the diatomaceous earth filter aid described in the present application, the rate of introduction of the acidic gas during the calcination in step (3) is 0.05-5 mL / min.

[0030] According to some embodiments of the method for preparing the diatomite filter aid described in the present application, the flux includes one or more of sodium hydroxide, potassium hydroxide and sodium carbonate.

[0031] According to some embodiments of the method for preparing the diatomite filter aid described in the present application, the amount of the flux is 0-8% of the mass of the diatomite refined soil.

[0032] The second aspect of the present application provides a diatomaceous earth filter aid, which is prepared by the preparation method described in the first aspect of the present application.

[0033] The SiO 2 The mass content of Al is ≥92%, 2 O 3 The mass content of Fe is ≤2%, 2 O 3 The mass content of iron is ≤0.2%, and the content of acid-soluble iron is <10mg / kg.

[0034] The beneficial effects of the present application include: the diatomaceous earth filter aid described in the present application is a pharmaceutical grade diatomaceous earth filter aid that meets the requirements of the United States Pharmacopoeia and the Chinese Pharmacopoeia. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a SEM image of the diatomite ore described in Example 1 of the present application;

[0036] Figure 2 This is the SEM image of the diatomaceous earth filter aid described in Example 1 of the present application. DETAILED DESCRIPTION

[0037] Embodiments of the present invention are described in detail below. The embodiments are exemplary and intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0038] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0039] The present invention provides a method for preparing a diatomaceous earth filter aid, comprising the following steps:

[0040] (1) calcining diatomite ore to obtain primary diatomite;

[0041] (2) subjecting the primary diatomaceous earth to an acid leaching treatment, and then washing the acid leached primary diatomaceous earth to obtain diatomaceous earth fine soil;

[0042] (3) Calcining diatomaceous earth in an acidic atmosphere to obtain the diatomaceous earth filter aid.

[0043] The preparation method of the diatomite filter aid described in the present application realizes the efficient removal of organic matter and clay mineral impurities in diatomite. Calcination removes organic matter in diatomite, and acid leaching removes Al 2 O 3 , Fe 2 O 3 The dissolution of clay mineral impurities such as CaO and MgO into salts not only improves the purity of diatomite, but also improves the pore structure of diatomite.

[0044] In some embodiments of the present application, the SiO 2 The mass content is 80%-85%; for example, 80%, 82%, 83%, 85%, etc.

[0045] In some embodiments of the present application, the particle size of the diatomite ore is less than or equal to 75 μm, for example, 75 μm, 70 μm, 68 μm, 65 μm, 62 μm, 60 μm, 57 μm, 53 μm, 50 μm, etc.

[0046] In some embodiments of the present application, the calcination temperature in step (1) is 200°C-800°C, such as 200°C, 260°C, 280°C, 320°C, 370°C, 460°C, 580°C, 630°C, 690°C, 760°C, 800°C, etc., and the calcination time is 0.5h-2h; such as 0.5h, 0.8h, 1.2h, 1.6h, 2h, etc. The pre-calcination temperature is set in the range of 200-800°C, which can achieve the purpose of activating diatomite while achieving the simultaneous removal of organic matter, which is beneficial to the acid leaching and dissolution of impurity metal ions in the later stage. If the temperature is too low, the purpose of effective activation and organic matter removal cannot be achieved, and the organic matter will affect the effect of removing impurity ions by acid leaching in the later stage; if the temperature is too high, the diatomite will be melted and sintered, which is not conducive to the leaching of impurity ions.

[0047] In some embodiments of the present application, the heating rate during calcination in step (1) is 0.5-20°C / min; for example, 0.5°C / min, 2°C / min, 5°C / min, 9°C / min, 13°C / min, 18°C / min, 20°C / min, etc.

[0048] In some embodiments of the present application, the acid leaching treatment includes mixing the primary diatomite, the acid leaching solution and the dispersant for acid leaching. The acid leaching solution used in the acid leaching process can be recycled 4-6 times, which solves the problem of acid consumption in the acid purification of diatomite in the existing preparation method. The addition of the dispersant can form a suspension between the primary diatomite and the acid leaching solution, which facilitates the acid leaching process.

[0049] In some embodiments of the present application, the acid leaching solution includes one or more of hydrochloric acid, sulfuric acid, nitric acid and perchloric acid.

[0050] In some embodiments of the present application, the dispersant includes sodium tripolyphosphate and sodium silicate. The dispersant selected in the present application is an inorganic dispersant, and an organic dispersant is not suitable for this system, which will affect the later metal ion removal and calcination effects. After sodium tripolyphosphate and sodium silicate are ionized in water, the diatomaceous earth particles can be kept in a dispersed state through electrostatic repulsion to prevent agglomeration. Sodium tripolyphosphate can rely on its solubility to increase the solubility of impurity metal ions, and can form a stable complex with metal ions through chelation; while sodium silicate can hydrolyze to generate silicate colloidal ions, which helps the diatomaceous earth solid particles to be evenly dispersed in the liquid, further promoting the metal ion dissolution reaction.

[0051] In some embodiments of the present application, the dosage ratio of the primary diatomite to the acid leaching solution is 1kg:2L-10L; for example, 1kg:2L, 1kg:4L, 1kg:6L, 1kg:8L, 1kg:10L, etc. Selecting this dosage ratio can fully promote the dissolution of metal ions during the diatomite acid leaching process. Too low will result in low production efficiency, and too high will result in insufficient reaction, affecting the purity of the diatomite and other product indicators in the later stage.

[0052] In some embodiments of the present application, the amount of the dispersant is 0.3%-0.5% of the mass of the primary diatomaceous earth; for example, 0.3%, 0.4%, 0.5%, etc.

[0053] In some embodiments of the present application, the concentration of the acid in the acid leaching solution is 1-10 mol / L; for example, 1 mol / L, 3 mol / L, 5 mol / L, 8 mol / L, 10 mol / L, etc.

[0054] In some embodiments of the present application, the mass ratio of the sodium tripolyphosphate and the sodium silicate in the dispersant is (0.8-1.2):1; for example, 0.8:1, 1:1, 1.2:1, etc.

[0055] In some embodiments of the present application, the acid leaching temperature is 70-100°C, such as 70°C, 75°C, 83°C, 92°C, 100°C, etc., and the acid leaching time is 2-12h, such as 2h, 5h, 8h, 12h, etc. At this acid leaching temperature, the metal ion dissolution reaction of impurity minerals such as montmorillonite, kaolin, mica, etc. can be fully promoted. It cannot be achieved at too low a temperature.

[0056] In some embodiments of the present application, the washing detergent includes deionized water, and the washing is stopped when the pH of the washing wastewater generated by the washing is greater than 5. Deionized water is used as circulating water to wash the diatomite, and a filter press is used for filtering each time the washing is performed. The countercurrent circulation washing method is used for 6-10 cycles of washing, and the highest concentration of the circulating water is discharged after each washing, and the remaining 5-9 circulating waters are washed in order of acid concentration. The last washing is performed with new deionized water until the pH value of the washing wastewater is greater than 5.

[0057] The countercurrent circulation washing method solves the problem of high water consumption in washing, reduces production costs and improves production efficiency.

[0058] In some embodiments of the present application, the water content of the diatomaceous earth is 40wt%-50wt%; for example, 40wt%, 43wt%, 45wt%, 48wt%, 50wt%, etc.

[0059] In some embodiments of the present application, the preparation method further comprises mixing diatomite fine soil and flux, and then calcining. The flux is mainly used to reduce the calcination temperature during the diatomite treatment process, which helps to decompose organic matter in the diatomite and crystallize silicon dioxide. The specific surface area and pore size of the diatomite after flux calcination are optimized, further improving its filtration performance and application effect, and adjusting its permeability and other properties.

[0060] In some embodiments of the present application, the acidic atmosphere includes chlorine and / or hydrogen chloride. The acidic gas can promote the reaction and precipitation of surface and shallow metal ions with gas components during the calcination process to generate volatile components, thereby achieving the purpose of diatomite purification and surface cleaning, and ultimately making it meet the various soluble metal ion requirements of pharmaceutical-grade filter aids.

[0061] In some embodiments of the present application, the calcination temperature in step (3) is 800°C-1200°C, such as 800°C, 900°C, 980°C, 1100°C, 1150°C, 1200°C, etc., and the calcination time is 0.5h-2h; such as 0.5h, 1.2h, 1.8h, 2h, etc. This temperature range can effectively achieve high-temperature precipitation and surface purification reaction of diatomite. If the temperature is too low, it is impossible to achieve a high metal ion precipitation and surface cleaning effect. If the temperature is too high, the diatomite will be crystallized and transformed into quartz, resulting in a decrease in product performance.

[0062] In some embodiments of the present application, the heating rate during calcination in step (3) is 0.5-20°C / min; for example, 0.5°C / min, 2.5°C / min, 5.3°C / min, 6.7°C / min, 8.9°C / min, 9.8°C / min, 10.8°C / min, 11.6°C / min, 15.7°C / min, 20°C / min, etc.

[0063] In some embodiments of the present application, the rate of introduction of the acidic gas during the calcination in step (3) is 0.05-5 mL / min; for example, 0.05 mL / min, 0.5 mL / min, 1.6 mL / min, 2.3 mL / min, 3.2 mL / min, 3.7 mL / min, 4.6 mL / min, 5 mL / min, etc.

[0064] In some embodiments of the present application, the flux includes one or more of sodium hydroxide, potassium hydroxide and sodium carbonate.

[0065] In some embodiments of the present application, the amount of the flux is 0-8% of the mass of the diatomite fine soil; for example, 0%, 2%, 5%, 8%, etc.

[0066] The present application also provides a diatomaceous earth filter aid, which is prepared by the preparation method described in the first aspect of the present application;

[0067] The SiO 2 The mass content of Al is ≥92%, 2 O 3 The mass content of Fe is ≤2%, 2 O 3 The mass content of iron is ≤0.2%, and the content of acid-soluble iron is <10mg / kg.

[0068] The technical solution of the present application is further described below in conjunction with specific embodiments.

[0069] Example 1

[0070] A method for preparing a diatomaceous earth filter aid comprises the following steps:

[0071] (1) SiO 2 The diatomite ore with a mass content of 80% and a particle size of 75 μm is placed in a muffle furnace for calcination at a temperature of 500° C. for 2 hours, and a heating rate and a cooling rate after calcination are both 5° C. / min to remove organic matter in the diatomite and obtain first-grade diatomite;

[0072] (2) The first-grade diatomite, acid leaching solution and dispersant are prepared into a suspension and placed in a reactor for acid leaching. The acid leaching solution used is a mixture of hydrochloric acid and sulfuric acid, wherein the mass ratio of hydrochloric acid to sulfuric acid is 1:1, the acid concentration of the acid leaching solution is 10 mol / L, the ratio of the mass of the first-grade diatomite to the volume of the acid leaching solution is 1 kg: 6 L, the dispersant is a mixture of sodium tripolyphosphate and sodium silicate, wherein the mass ratio of sodium tripolyphosphate to sodium silicate is 1:1, and the amount of the dispersant is 0.4 wt% of the mass of the first-grade diatomite. The acid leaching temperature is 80 ° C, and the acid leaching time is 10 h;

[0073] (3) After acid leaching, the first-grade diatomite suspension is filtered and washed using a filter press. The washing agent used for washing is deionized water. The first-grade diatomite is washed until the pH value reaches above 5, thereby obtaining diatomite fine soil with a water content of 50 wt%.

[0074] (4) 2% by weight of sodium carbonate was added to diatomite fine soil to mix to obtain a mixture, and the mixture was placed in a chlorine atmosphere for calcination at a calcination temperature of 1000° C. for 2 h. The heating rate and the cooling rate after the calcination were both 5° C. / min. The chlorine gas flow rate during the calcination process was 0.5 mL / min. After calcination, a medical grade diatomite filter aid was obtained.

[0075] Example 2

[0076] The only difference between Example 2 and Example 1 is that the calcination temperature in step (4) of the diatomaceous earth filter aid preparation process in Example 2 is 850° C., and the remaining operations are the same as in Example 1.

[0077] The specific steps include:

[0078] A method for preparing a diatomaceous earth filter aid comprises the following steps:

[0079] (1) SiO 2 The diatomite ore with a mass content of 80% and a particle size of 75 μm is placed in a muffle furnace for calcination at a temperature of 500° C. for 2 hours, and a heating rate and a cooling rate after calcination are both 5° C. / min to remove organic matter in the diatomite and obtain first-grade diatomite;

[0080] (2) The first-grade diatomite, acid leaching solution and dispersant are prepared into a suspension and placed in a reactor for acid leaching. The acid leaching solution used is a mixture of hydrochloric acid and sulfuric acid, wherein the mass ratio of hydrochloric acid to sulfuric acid is 1:1, the acid concentration of the acid leaching solution is 10 mol / L, the ratio of the mass of the first-grade diatomite to the volume of the acid leaching solution is 1 kg: 6 L, the dispersant is a mixture of sodium tripolyphosphate and sodium silicate, wherein the mass ratio of sodium tripolyphosphate to sodium silicate is 1:1, and the amount of the dispersant is 0.4 wt% of the mass of the first-grade diatomite. The acid leaching temperature is 80 ° C, and the acid leaching time is 10 h;

[0081] (3) After acid leaching, the first-grade diatomite suspension is filtered and washed using a filter press. The washing agent used for washing is deionized water. The first-grade diatomite is washed until the pH value reaches above 5, thereby obtaining diatomite fine soil with a water content of 50 wt%.

[0082] (4) 2% by weight of sodium carbonate was added to diatomite fine soil to mix to obtain a mixture, and the mixture was placed in a chlorine atmosphere for calcination at a calcination temperature of 850° C. for 2 h. The heating rate and the cooling rate after the calcination were both 5° C. / min. The chlorine gas flow rate during the calcination process was 0.5 mL / min. After calcination, a medical grade diatomite filter aid was obtained.

[0083] Example 3

[0084] The only difference between Example 3 and Example 1 is that the calcination temperature in step (4) of the diatomaceous earth filter aid preparation process described in Example 3 is 1100° C., and the remaining operations are the same as in Example 1.

[0085] The specific steps include:

[0086] A method for preparing a diatomaceous earth filter aid comprises the following steps:

[0087] (1) SiO 2The diatomite ore with a mass content of 80% and a particle size of 75 μm is placed in a muffle furnace for calcination at a temperature of 500° C. for 2 hours, and a heating rate and a cooling rate after calcination are both 5° C. / min to remove organic matter in the diatomite and obtain first-grade diatomite;

[0088] (2) The first-grade diatomite, acid leaching solution and dispersant are prepared into a suspension and placed in a reactor for acid leaching. The acid leaching solution used is a mixture of hydrochloric acid and sulfuric acid, wherein the mass ratio of hydrochloric acid to sulfuric acid is 1:1, the acid concentration of the acid leaching solution is 10 mol / L, the ratio of the mass of the first-grade diatomite to the volume of the acid leaching solution is 1 kg: 6 L, the dispersant is a mixture of sodium tripolyphosphate and sodium silicate, wherein the mass ratio of sodium tripolyphosphate to sodium silicate is 1:1, and the amount of the dispersant is 0.4 wt% of the mass of the first-grade diatomite. The acid leaching temperature is 80 ° C, and the acid leaching time is 10 h;

[0089] (3) After acid leaching, the first-grade diatomite suspension is filtered and washed using a filter press. The washing agent used for washing is deionized water. The first-grade diatomite is washed until the pH value reaches above 5, thereby obtaining diatomite fine soil with a water content of 50 wt%.

[0090] (4) 2% by weight of sodium carbonate was added to diatomite fine soil to mix to obtain a mixture, and the mixture was placed in a chlorine atmosphere for calcination at a calcination temperature of 1100° C. for 2 h, a heating rate and a cooling rate after calcination were both 5° C. / min, and a chlorine gas flow rate during the calcination process was 0.5 mL / min. After calcination, a medical grade diatomite filter aid was obtained.

[0091] Example 4

[0092] The only difference between Example 4 and Example 1 is that the calcination temperature in step (4) of the diatomaceous earth filter aid preparation process described in Example 4 is 1200° C., and the remaining operations are the same as in Example 1.

[0093] The specific steps include:

[0094] A method for preparing a diatomaceous earth filter aid comprises the following steps:

[0095] (1) SiO 2 The diatomite ore with a mass content of 80% and a particle size of 75 μm is placed in a muffle furnace for calcination at a temperature of 500° C. for 2 hours, and a heating rate and a cooling rate after calcination are both 5° C. / min to remove organic matter in the diatomite and obtain first-grade diatomite;

[0096] (2) The first-grade diatomite, acid leaching solution and dispersant are prepared into a suspension and placed in a reactor for acid leaching. The acid leaching solution used is a mixture of hydrochloric acid and sulfuric acid, wherein the mass ratio of hydrochloric acid to sulfuric acid is 1:1, the acid concentration of the acid leaching solution is 10 mol / L, the ratio of the mass of the first-grade diatomite to the volume of the acid leaching solution is 1 kg: 6 L, the dispersant is a mixture of sodium tripolyphosphate and sodium silicate, wherein the mass ratio of sodium tripolyphosphate to sodium silicate is 1:1, and the amount of the dispersant is 0.4 wt% of the mass of the first-grade diatomite. The acid leaching temperature is 80 ° C, and the acid leaching time is 10 h;

[0097] (3) After acid leaching, the first-grade diatomite suspension is filtered and washed using a filter press. The washing agent used for washing is deionized water. The first-grade diatomite is washed until the pH value reaches above 5, thereby obtaining diatomite fine soil with a water content of 50 wt%.

[0098] (4) adding 2% by weight of sodium carbonate to diatomite fine soil to mix to obtain a mixture, placing the mixture in a chlorine atmosphere for calcination, the calcination temperature is 1200° C., the calcination time is 2 h, the heating rate and the cooling rate after the calcination are both 5° C. / min, the chlorine gas flow rate during the calcination process is 0.5 mL / min, and a medical grade diatomite filter aid is obtained after calcination.

[0099] Example 5

[0100] The only difference between Example 5 and Example 1 is that in the preparation process of the diatomite filter aid described in Example 5, a mixed solution of sulfuric acid and nitric acid is used instead of a mixed solution of hydrochloric acid and sulfuric acid for acid leaching, wherein the mass ratio of sulfuric acid to nitric acid is 2:1, and the remaining operating steps are the same as those in Example 1.

[0101] Example 6

[0102] The only difference between Example 6 and Example 1 is that in the preparation process of the diatomaceous earth filter aid described in Example 6, hydrochloric acid is used instead of a mixed solution of hydrochloric acid and sulfuric acid for acid leaching, and the remaining operating steps are the same as those in Example 1.

[0103] Example 7

[0104] The only difference between Example 7 and Example 1 is that sulfuric acid is used instead of a mixed solution of hydrochloric acid and sulfuric acid for acid leaching during the preparation of the diatomaceous earth filter aid described in Example 7, and the remaining operating steps are the same as those in Example 1.

[0105] Comparative Example 1

[0106] The difference between Comparative Example 1 and Example 1 is that, in the preparation process of the diatomaceous earth filter aid described in Comparative Example 1, acid leaching is first performed and then calcination is performed.

[0107] The specific steps include:

[0108] A method for preparing a diatomaceous earth filter aid comprises the following steps:

[0109] (1) SiO 2 Diatomite ore with a mass content of 80% and a particle size of 75μm, acid leaching solution and dispersant are configured into a suspension and placed in a reactor for acid leaching. The acid leaching solution used is a mixture of hydrochloric acid and sulfuric acid, wherein the mass ratio of hydrochloric acid to sulfuric acid is 1:1, the acid concentration of the acid leaching solution is 10mol / L, the ratio of the mass of the diatomite ore to the volume of the acid leaching solution is 1kg:6L, the dispersant is a mixture of sodium tripolyphosphate and sodium silicate, wherein the mass ratio of sodium tripolyphosphate to sodium silicate is 1:1, and the amount of the dispersant is 0.4wt% of the mass of the diatomite ore. The acid leaching temperature is 80℃, and the acid leaching time is 10h.

[0110] (2) After acid leaching, the first-grade diatomite suspension is filtered and washed using a filter press. The washing agent used for washing is deionized water. The first-grade diatomite is washed until the pH value reaches above 5, thereby obtaining diatomite fine soil with a water content of 50 wt%.

[0111] (3) calcining the diatomite in a muffle furnace at a temperature of 500° C. for 2 h, with a heating rate and a cooling rate after calcination both at 5° C. / min to remove organic matter from the diatomite and obtain primary diatomite;

[0112] (4) adding 2% by weight of sodium carbonate to the primary diatomaceous earth and mixing to obtain a mixture, placing the mixture in a chlorine atmosphere for calcination, the calcination temperature is 1000° C., the calcination time is 2 h, the heating rate and the cooling rate after the calcination are both 5° C. / min, the chlorine gas flow rate during the calcination process is 0.5 mL / min, and a pharmaceutical grade diatomaceous earth filter aid is obtained after calcination.

[0113] Comparative Example 2

[0114] The difference between Comparative Example 2 and Example 1 is that the calcination in step (4) of the preparation process of the diatomaceous earth filter aid in Comparative Example 2 is carried out in an air atmosphere.

[0115] The specific steps include:

[0116] A method for preparing a diatomaceous earth filter aid comprises the following steps:

[0117] (1) SiO 2 The diatomite ore with a mass content of 80% and a particle size of 75 μm is placed in a muffle furnace for calcination at a temperature of 500° C. for 2 hours, and a heating rate and a cooling rate after calcination are both 5° C. / min to remove organic matter in the diatomite and obtain first-grade diatomite;

[0118] (2) The first-grade diatomite, acid leaching solution and dispersant are prepared into a suspension and placed in a reactor for acid leaching. The acid leaching solution used is a mixture of hydrochloric acid and sulfuric acid, wherein the mass ratio of hydrochloric acid to sulfuric acid is 1:1, the acid concentration of the acid leaching solution is 10 mol / L, the ratio of the mass of the first-grade diatomite to the volume of the acid leaching solution is 1 kg: 6 L, the dispersant is a mixture of sodium tripolyphosphate and sodium silicate, wherein the mass ratio of sodium tripolyphosphate to sodium silicate is 1:1, and the amount of the dispersant is 0.4 wt% of the mass of the first-grade diatomite. The acid leaching temperature is 80 ° C, and the acid leaching time is 10 h;

[0119] (3) After acid leaching, the first-grade diatomite suspension is filtered and washed using a filter press. The washing agent used for washing is deionized water. The first-grade diatomite is washed until the pH value reaches above 5, thereby obtaining diatomite fine soil with a water content of 50 wt%.

[0120] (4) adding 2% by weight of sodium carbonate to diatomite fine soil to mix to obtain a mixture, placing the mixture in a muffle furnace for calcination at a temperature of 1000° C. for 2 h, and a heating rate and a cooling rate after the calcination are both 5° C. / min to obtain a pharmaceutical grade diatomite filter aid.

[0121] Comparative Example 3

[0122] The difference between Comparative Example 3 and Example 1 is that in the preparation process of the diatomaceous earth filter aid described in Comparative Example 3, the primary diatomaceous earth is directly calcined in step (4) without adding a flux.

[0123] The specific steps include:

[0124] (1) SiO 2 The diatomite ore with a mass content of 80% and a particle size of 75 μm is placed in a muffle furnace for calcination at a temperature of 500° C. for 2 hours, and a heating rate and a cooling rate after calcination are both 5° C. / min to remove organic matter in the diatomite and obtain first-grade diatomite;

[0125] (2) The first-grade diatomite, acid leaching solution and dispersant are prepared into a suspension and placed in a reactor for acid leaching. The acid leaching solution used is a mixture of hydrochloric acid and sulfuric acid, wherein the mass ratio of hydrochloric acid to sulfuric acid is 1:1, the acid concentration of the acid leaching solution is 10 mol / L, the ratio of the mass of the first-grade diatomite to the volume of the acid leaching solution is 1 kg: 6 L, the dispersant is a mixture of sodium tripolyphosphate and sodium silicate, wherein the mass ratio of sodium tripolyphosphate to sodium silicate is 1:1, and the amount of the dispersant is 0.4 wt% of the mass of the first-grade diatomite. The acid leaching temperature is 80 ° C, and the acid leaching time is 10 h;

[0126] (3) After acid leaching, the first-grade diatomite suspension is filtered and washed using a filter press. The washing agent used for washing is deionized water. The first-grade diatomite is washed until the pH value reaches above 5, thereby obtaining diatomite fine soil with a water content of 50 wt%.

[0127] (4) The diatomite fine soil is placed in a chlorine atmosphere for calcination, the calcination temperature is 1000° C., the calcination time is 2 h, the heating rate and the cooling rate after the calcination are both 5° C. / min, and the chlorine gas flow rate during the calcination process is 0.5 mL / min. After calcination, a medical grade diatomite filter aid is obtained.

[0128] The technical indicators of the diatomaceous earth filter aids described in Examples 1-7 and Comparative Examples 1-3 of the present application are shown in Table 1:

[0129] Table 1

[0130]

[0131] It can be seen from Table 1 that within the calcination range of the claims, the higher the calcination temperature, the higher the SiO 2 The higher the content, the 2 O 3 and Fe 2 O 3 The lower the impurity content, the higher the whiteness, the lower the acid-soluble iron, washable lead, washable arsenic, citric acid / ethanol soluble aluminum and other indicators, the higher the permeability, and the endotoxin indicators are all 0 due to high-temperature treatment; within the acid leaching test range of the claims, the use effect of the mixed acid is better than that of the single acid, and the use effect of sulfuric acid in the single acid is better than that of hydrochloric acid; for the calcination atmosphere, the chlorine calcination atmosphere is significantly better than the air atmosphere, which further illustrates that the atmosphere is conducive to the further reactive escape of impurity metal ions, and ultimately achieves the improvement of product purity and the reduction of impurity content, the increase of whiteness and permeability, and the reduction of acid-soluble iron, washable lead, washable arsenic, citric acid / ethanol soluble aluminum and other indicators. In addition, the effect of pre-calcination followed by acid leaching in the preparation process of diatomite filter aid is better than that of acid leaching followed by calcination, which illustrates that the pre-calcination process is more conducive to the removal of organic matter and the activation of diatomite to remove metal ions.

[0132] The SEM image of the diatomite ore described in Example 1 of the present application is as follows: Figure 1 As shown, the SEM image of the diatomaceous earth filter aid described in Example 1 is as follows Figure 2 shown.

[0133] from Figure 1 and Figure 2It can be seen that after the combined treatment process of air pre-calcination-mixed acid leaching-acidic reaction atmosphere calcination, the impurity mineral content of the obtained diatomite filter aid is significantly reduced, the diatomite surface is smoother, and it is more conducive to improving indicators such as filtration rate and improving application performance.

[0134] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present invention.

Claims

1. A method for preparing a diatomaceous earth filter aid, characterized in that: The following steps are involved: (1) calcining diatomite ore to obtain primary diatomite; (2) subjecting the primary diatomaceous earth to an acid leaching treatment, and then washing the acid leached primary diatomaceous earth to obtain diatomaceous earth fine soil; (3) Calcining diatomaceous earth in an acidic atmosphere to obtain the diatomaceous earth filter aid.

2. The method for preparing the diatomite filter aid according to claim 1, characterized in that: The mass content of SiO2 in the diatomite ore is 80%-85%; And / or, the particle size of the diatomite ore is less than or equal to 75 μm; And / or, the calcination temperature in step (1) is 200°C-800°C, and the calcination time is 0.5h-2h; And / or, the heating rate during calcination in step (1) is 0.5-20°C / min.

3. The method for preparing the diatomite filter aid according to claim 1, characterized in that: The acid leaching treatment comprises mixing the primary diatomaceous earth, the acid leaching solution and the dispersant, and performing the acid leaching treatment.

4. The method for preparing the diatomite filter aid according to claim 3, characterized in that: The acid leaching solution includes one or more of hydrochloric acid, sulfuric acid, nitric acid and perchloric acid; And / or, the dispersant includes sodium tripolyphosphate and sodium silicate; And / or, the dosage ratio of the primary diatomaceous earth to the acid leaching solution is 1kg:2L-10L; And / or, the amount of the dispersant used is 0.3%-0.5% of the mass of the first-grade diatomaceous earth.

5. The method for preparing the diatomite filter aid according to claim 4, characterized in that: The acid concentration in the acid leaching solution is 1-10 mol / L; And / or, the mass ratio of the sodium tripolyphosphate to the sodium silicate in the dispersant is (0.8-1.2):

1.

6. The method for preparing the diatomite filter aid according to claim 1, characterized in that: The acid leaching temperature is 70-100° C., and the acid leaching time is 2-12 hours.

7. The method for preparing the diatomite filter aid according to claim 1, characterized in that: The washing agent used in the washing includes deionized water, and the washing is stopped when the pH of the washing wastewater generated by the washing is greater than 5; And / or, the water content of the diatomaceous earth is 40wt%-50wt%.

8. The method for preparing the diatomite filter aid according to claim 1, characterized in that: The preparation method further comprises mixing diatomite fine soil and flux, and then calcining; and / or, the acidic atmosphere comprises chlorine and / or hydrogen chloride; And / or, the calcination temperature in step (3) is 800° C.-1200° C., and the calcination time is 0.5 h-2 h; And / or, the heating rate during calcination in step (3) is 0.5-20°C / min; And / or, the acid gas introduction rate during the calcination in step (3) is 0.05-5 mL / min.

9. The method for preparing the diatomaceous earth filter aid according to claim 8, characterized in that: The flux comprises one or more of sodium hydroxide, potassium hydroxide and sodium carbonate; And / or, the amount of the flux is 0-8% of the mass of the diatomite refined soil.

10. A diatomaceous earth filter aid, characterized in that: The diatomaceous earth filter aid is prepared by the preparation method according to any one of claims 1 to 9; The mass content of SiO2 in the diatomite filter aid is ≥92%, the mass content of Al2O3 is ≤2%, the mass content of Fe2O3 is ≤0.2%, and the content of acid-soluble iron is <10 mg / kg.

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