ENRICHMENT OF LOW-GRADE POLYHALITE FROM HIGH-GRADE SODIUM SULFATE-CONTAINING ORES THROUGH SELECTIVE LEACHING AND PRODUCTION METHOD OF POLYHALITE FERTILIZER AND SODIUM SULFATE

Abstract

The invention relates to an integrated production process that enables the simultaneous and high-yield recovery of polyhalite fertilizer and sodium sulfate products from complex ore structures containing high-grade sodium sulfate (Tenardite, Blödite and Globerite; >20% Na₂O) and low-grade polyhalite (<8-10% K₂O), by eliminating the disadvantages of calcination and high-energy heat treatments in the current state of the art. In the process, raw ore with a size of 800-1000 mm is gradually reduced to a size of 20-50 mm in the jaw crusher (110) and cone crusher (120) and then fed into the leaching tank (130). At the same time, sodium sulfate solution (301), whose concentration is adjusted according to the ore content, is fed into the leaching tank from the solution tank (300); by the common ion effect of the sodium and sulfate ion concentration in this solution, the self-dissolution equilibrium of the polyhalite mineral is suppressed, preventing the dissolution of potassium and magnesium salts and ensuring that only the sodium sulfate in the ore selectively passes into the liquid phase. After the solid-liquid separation provided in Filter Press-1 (140), polyhalite fertilizer (161) is obtained from the solid phase by Rotary Dryer-1 (150) and Pellet Mill (160); sodium sulfate (201) is produced from the liquid phase by Evaporator (170) and Crystallizer (180). The low concentration solution (192) separated in Filter Press-2 (190) is fed back to the solution tank (300) to ensure closed-loop production. The main advantages of this invention include: using a sodium sulfate solution obtained from the process's own product stream instead of an external chemical reagent as a leaching agent; offering a simplified process flow due to the absence of a calcium-derived byproduct (gypsum); operating on a zero-waste principle by converting almost all components in the ore into economic value; recovering all used process water back into the system; preventing harmful gas emissions such as CO₂ and SO₂; and significantly lower energy consumption compared to conventional methods.

Description

1 TARIFF CONTAINING HIGH-GRADE SODIUM SULFATE AND LOW-GRADE POLYHALITE POLYHALITE FERTILIZER AND SODIUM SULFATE BY SELECTIVE LEACHING FROM ORES PRODUCTION METHOD 5 1. THE TECHNICAL FIELD TO WHICH THE INVENTION RELATES This invention enables the processing of ores containing high-grade sodium sulfate and low-grade polyhalite. Processing by selective leaching using sodium sulfate solution. As a result, the polyhalite mineral phase is preserved, and polyhalite fertilizer and sodium sulfate 10 are produced. It relates to a production method that enables the simultaneous acquisition of its products. The invention is particularly geared towards the enrichment of complex ores of evaporite origin. and is the conversion of low-grade polyhalite ore into high-grade polyhalite concentrate. conversion and recovery of sodium sulfate present in the solution with high efficiency It is part of an integrated process that enables its acquisition. 15 Polyhalite, with the chemical formula K₂Ca₂Mg(SO₄)₄·2H₂O, is a potassium, calcium, A naturally occurring sulfate that contains magnesium and sulfate ions within the same crystal structure. It is a mineral. Due to the plant nutrients it contains, it is directly very nutritious. It can be used as a raw material for elemental fertilizers. Ore Characterization and Grade Classification 20 In the industrial evaporite literature, sodium sulfate deposits are considered to have sodium oxide potential. When classified according to these criteria, values ​​of 20% Na₂O and above are considered "High Grade / Rich Ore". It is considered to be of class (MTA, 2010; Zhang et al., 2018). Ore Class, Na₂O Grade Limit, Dominant Mineralogy and Characteristic High Grade (Rich) > 20% Massive tenardite and very little clay. globerite phases. Low Impurity, easy solubility. Medium grade 12% - 20% Typical clayey globerite layers and blödit transitions. Low Grade (Complex) < 12% High bloidite, marl, clay and Gypsum / anhydride mixture. According to the reference classifications in the literature (see doi: 25 10.1021 / acsomega.3c04733), the approximate K₂O content of polyhalite ores. The distribution according to percentages is summarized in the table below: Ore Type Approximate K₂O (%) Mass Percentage High-grade polyhalite > 12 - 14 Medium Grade Polyhalite 8 - 12 Low-grade polyhalite < 8 - 10 2 The raw material / ore that is the subject of the invention is classified as "High" according to the tables above. The classes "High-Grade Sodium Sulfate" and "Low-Grade Polyhalite" are found together. It is a complex type of ore. 2. STATE OF KNOWLEDGE OF THE ART A. Limitations of Heat Treatment and Calcination-Focused Approaches 5 - Energy-Intensive Operations: Extreme temperatures ranging from 800-1000°C. These requirements increase fossil fuel consumption and production costs. - Ecological Deformation: SO₂ and CO₂ released during thermal decomposition. Emissions pose an environmental risk. - Mineralogical Losses: Uncontrolled heat transfer, Polyhalite complex crystal 10 It causes irreversible damage to its structure. B. Inadequacy of Physical and Dry Enrichment Methods - Selectivity Vulnerability: Mineral components with similar density values. It cannot be completely separated in dry separation systems. - Fine Grain Loss: Fine grains with high economic value are lost during screening and classification. Factions are escaping the system. - Dust and Occupational Safety Issues: High dust emissions from mechanical grinding cause occupational safety problems. This creates a security risk. C. Previous Applications of the Applicant - Patent No. 2026 / 003253, dated 04.03.2026, belonging to the applicant. application ("First Application"); containing polyhalite, sodium sulfate and magnetite through wet grinding, magnetic separation and acidic leaching steps from ores Polyhalite mineral consists of K₂SO₄, MgSO₄, gypsum, and concentrated iron ore. It concerns the complete disintegration of the system into its individual components; in this application Polyhalite is not obtained as a whole fertilizer product. 25 - Patent number 2026 / 010652, dated 29.06.2026, belonging to the applicant. application ("Second Application"); containing low-grade polyhalite and sodium sulfate Polyhalite phase from ores by selective leaching with calcium nitrate solution The study focuses on the production of polyhalite fertilizer, sodium sulfate, and gypsum while maintaining preservation. - The present invention constitutes a separate patent application, independent of the First and Second Applications. 30 It is presented as follows. Unlike the Second Application, the present invention is a leaching agent. by using sodium sulfate solution instead of calcium nitrate, and thus It differs from the First Application in that it does not involve gypsum production; Polyhalite mineral phase as a fertilizer product in its whole form without decomposition. It is based on winning. 35 - As of the application date, neither the First Application nor the Second Application has been processed yet. It has not been published. 3. TECHNICAL SOLUTIONS AND PRODUCT FEATURES GENERATED BY THE INVENTION I. Highly Purified Polyhalite Fertilizer Grey-white in color, in crystalline or micronized powder form, with controlled release in water 40 It has a stable structure. Its chemical formula is K₂Ca₂Mg(SO₄)₄·2H₂O, and its molecular structure is... Its weight is 602.94 g / mol. 3 II. Sodium Sulfate (Na₂SO₄) The process produces the product in anhydrous or decahydrate (Glauber's salt) forms, depending on the need. It has the flexibility to do so. Thanks to its high resolution and purity rate, glass, It provides raw material input to sectors such as the detergent and paper industries. Selective Leaching Mechanism 5 The dissolution equilibrium of polyhalite mineral in aqueous medium is expressed by the following equation: is being done: K₂Ca₂Mg(SO₄)₄·2H₂O ⇌ 2K⁺ + Mg²⁺ + 2Ca²⁺ + 4SO₄²⁻ + 2H₂O The concentration of sulfate (SO₄²⁻) ions in the solution is increased by adding sodium sulfate to the leaching solution. Increasing the balance to the left by 10 degrees, in accordance with the common ion effect and Le Chatelier's principle, By sliding it, it suppresses the solubility of the polyhalite mineral and the mineral in the solid phase. This ensures that it remains in place. In contrast, it is found in a free state within the ore. Sodium sulfate (tenardite / blodite / globerite phases) has the following dissolution equilibrium: According to this, it continues to transition to the liquid phase: Na₂SO₄ (s) ⇌ 2Na⁺ + SO₄²⁻ 15 The concentration of the leaching solution depends on the sodium sulfate and polyhalite content of the ore; It will dissolve the free sodium sulfate from the ore, but not the solubility of the polyhalite phase. to be kept within a range (2-25%) that will suppress it through the common ion effect It is being adjusted. Figures and Components That Will Aid in Understanding the Invention 20 In order to best understand the structure and advantages of the present invention It should be evaluated together with the figures explained below. [Attachment to file] Figure 1 shows a schematic representation of the process, and Figure 2 shows the P&ID (Pipe Identification) of the process. The diagram includes a representation of the lines and instrumentation. Part References - 100 Ore Stock - 110 Jaw Crusher - 120 Cone Crusher - 130 Leaching Tanks 30 - 140 Filter Press-1 - 150 Rotary Dryer-1 - 160 Pellet Mills - 170 Evaporators - 180 Crystallizer 35 - 190 Filter Press-2 - 200 Rotary Dryer-2 - 300 Solution Tanks 4 Current References - 101 Raw Ore Feeding - 111 Jaw crusher output, crushed ore to size 100-300 mm. - 121 Cone crusher output, crushed ore to size 20-50 mm (ready for leaching) size) 5 - 131 Mixture resulting from the leaching process - Polyhalite concentrate separated in Filter Press-1, 141 - 142 Filter Press-1 downstream (sodium sulfate solution) - 151 Dried Polyhalite - 161 Pelleted Polyhalite fertilizer product 10 - 171 Solution with increased density in the evaporator - Condensed water obtained from 172 evaporators. - 181 Sodium sulfate solidified in the crystallizer. - Solid sodium sulfate separated in Filter Press-2, 191 - 192 Low concentration sodium sulfate solution separated in Filter Press-2 15 - 201 Dried sodium sulfate product - 301 Concentrated sodium fed from solution tank to leaching tank. sulfate solution Detailed Description of the Invention Raw material (101) with a size of 800-1000 mm taken from the ore stock (100), pre-20 It is sent to the jaw crusher (110) for crushing. The 100-300 mm coming out of here The material of size (111) is conveyed to the Cone Crusher (120). The material coming out of the crusher is 20-50 mm. Material suitable for leaching (121) of the specified size is fed into the Leaching Tank (130). Sodium sulfate taken from Solution Tank (300) with concentration adjusted between 2-25%. Solution (301) is also sent to the Leaching Tank (130) in the same way. Leaching process is carried out at 15°C - 25 It is carried out at a temperature range of 50°C for a duration of 3-30 minutes. Under these conditions, leaching... the agent consists exclusively of sodium sulfate solution and calcium is present in the medium Due to the absence of any calcium-derived component, no calcium is lost during leaching. No sulfate (gypsum) precipitate forms. The presence of magnetite ore in the ore content of our first application is a major 30 This creates a disadvantage. Therefore, the iron minerals in the ore... Grinding is required for removal. Reduced to a suitable size. Iron minerals are separated from the ore using a magnetic separator. The removal of iron minerals is ensured. However, there are iron minerals in the ore here. Because of this, the ore was subjected to a separation process with a high particle size. 35 And energy consumption has been kept low. When the ore structure is examined, sodium sulfate phases (tenardite, bloidite, globerite), The polyhalite is not confined within the crystal lattice; it is located at the grain boundaries. It is found in blood vessels and pores, either freely or loosely bound. Therefore, the transfer of sodium sulfate into the solution does not require internal diffusion into the mineral, 40 It proceeds via a rapid dissolution mechanism occurring at the surface / grain boundary. This feature allows for short contact times, even with relatively coarse grain sizes such as 20-50 mm. This enables highly efficient selective dissolution (3-30 minutes). In contrast, the polyhalite phase is more tightly bound within the crystal lattice, and Since solubility is suppressed by the common ion effect, under these time and particle size conditions... It does not undergo significant dissolution. 5 The material processed in the leaching tank (131) is separated into solid and liquid. The filter is fed to Pres-1 (140). Polyhalite concentrate (141) separated in Filter Press-1 (140) is transferred to Rotary Dryer-1. (150) is sent; the moisture content adjusted product (151) coming out of here is made into suitable granules. It is sent to the Pellet Mill (160) to be converted into pellet granules. The product exits the system as Polyhalite Fertilizer (161). The liquid phase (142), which is the downstream of Filter Pres-1 (140), is used to increase the density of the liquid. It is fed into the evaporator (170). The solution, whose density is increased in the evaporator (171), It is fed into the crystallizer (180). Here, the solution undergoes a cooling process. Mixture for separating the crystals and liquid phase formed (181), Filter Press-2 (190) 15 The solid sodium sulfate (191) separated in the filter press is sent to the Rotary Dryer-2. (200) is fed. The material, brought to the appropriate moisture content in the rotary dryer (201), is sold. The chemical sodium sulfate is removed from the system as a ready-to-use chemical. Low concentration sodium sulfate solution (192) separated in Filter Press-2 (190), Solution It was sent back to the tank (300) to avoid any product loss, and then 20 more were sent back. It is included in the cycle. Condensed water (172) obtained from the evaporator (170) is also included in the cycle. The process water is fed back into the Solution Tank (300) in a closed loop. It is circulated within the system. Experimental Results / Pilot Scale Data Pilot-level experiments showed that processing 1 ton of ore yields 25 The results obtained are explained below. Processing 1 ton of raw ore yields 460 kg of ore. 440 kg of sodium sulfate was obtained during the production of polyhalite fertilizer. Ore leaching. When subjected to this process, the recovery yield of polyhalite mineral is 93.15%. The recovery efficiency of sodium sulfate selectively separated from the ore is 96.2%. It is presented as follows: 30 Leaching process parameters Value Temperature 15°C - 50°C Concentration 2-25% Duration: 3-30 minutes ✎ ADDED: The following XRF analysis data and yield calculations were provided by you. It was submitted, but I inadvertently omitted it from the previous draft. It is being added now. Raw Ore XRF Analysis Results Component Raw Ore (%) K₂O 6.38 Na₂O 20.07 35 6 Analysis Results of Enriched Ore (Polyhalite Product) Component Enriched Ore (%) K₂O 12.92 Depending on the characteristics of the ore being fed, the process is carried out using the parameters mentioned above. The following was determined from the enriched sample obtained after the leaching process: Calculations have been made: 5 The K₂O content in the raw ore is 6.38%; 1000 kg of raw ore contains 1000 kg × 0.0638 = 63.8 kg of K₂O is present. The amount of K₂O in the enriched ore. The concentration is 12.92%; in 460 kg of enriched ore, there are 460 kg × 0.1292 = 59.432 kg of K₂O. Accordingly, the polyhalite recovery efficiency is 59.432 / 63.8 = 93.15%. is being calculated. 10 The amount of sodium sulfate in the raw ore is 2.28 times the percentage of Na₂O. It is calculated by multiplying: %Na₂O = 20.07 × 2.28 = 45.76%; 1000 kg raw The ore contains 1000 kg × 0.4576 = 457.6 kg of sodium sulfate. The sodium produced... The amount of sulfate was measured as 440 kg, and accordingly, the sodium sulfate recovery efficiency was... 440 / 457.6 = 96.2% is calculated. 15 Pelletizing Process Pelleting is the process of transforming powdered or fine-grained materials into a form that is of a specific size and shape. This is the process of turning the product into pellets. This process ensures the standardization of product quality. It offers advantages such as ease of transport and storage, and reduced dust generation.

Claims

7 REQUESTS 1. From ores containing high-grade sodium sulfate and low-grade polyhalite, the leaching agent consists exclusively of sodium sulfate solution and leaching 5 Selective leaching in which no calcium-derived precipitate (gypsum) is formed. This process involves the incorporation of sodium sulfate into the liquid phase, preserving the polyhalite mineral phase, and... As a result of the process, polyhalite fertilizer (161) and sodium sulfate (201) products were produced simultaneously. It is a production method that enables its obtainment in this form; its characteristic is; - Raw ore of size 800-1000 mm taken from the ore stock (100) is processed with a jaw 10 Grain suitable for leaching in stages with crusher (110) and cone crusher (120) reduced in size, - Leaching with sodium sulfate solution (301) prepared at the appropriate concentration to be subjected to the process, - By preventing the dissolution of potassium and magnesium salts through the leaching process, 15 High-efficiency selective transfer of sodium sulfate to the liquid phase, - Obtaining the polyhalite product from the solid phase, - Obtaining sodium sulfate salt from the liquid phase, A production method characterized by its inclusion.

2. A method that conforms to Claim 1 and has the following characteristic: - Suitable grain size according to the amount of polyhalite and sodium sulfate contained in the raw ore. reduced in size, - Feeding the ore, which has been brought to the appropriate size, into the leaching tank (130), - Leaching process with sodium sulfate solution (301) adjusted according to ore content 25 subjection to - Potassium and magnesium salts by adjusting the concentration of the solution. By preventing its dissolution, sodium sulfate is selectively transferred to the liquid phase. passing, - Separation of the solid phase containing polyhalite in Filter Press-1 (140) after leaching, 30 - Drying of the separated solid phase in Rotary Dryer-1 (150), - The dried material is granulated in the Pellet Mill (160), The production method of Polyhalite fertilizer (161) is characterized by its content. 8 3. A method that complies with Claim 1 and has the following characteristic: - The solid phase of the sodium sulfate-containing solution obtained after the leaching process. his departure - Concentrating the purified solution in the Evaporator (170), - Sodium sulfate 5 is obtained by cooling the concentrated solution in the Crystallizer (180). the formation of crystals, - The crystals separated in Filter Press-2 (190) are dried in Rotary Dryer-2 (200) sodium sulfate product with suitable particle size and moisture content (201) transformation, Sodium Sulfate (201) production method characterized by its content. 10 4. A method that complies with Claim 1 and has the following characteristics: - Solutions obtained after filtration and crystallization processes (192) feed it back into the Solution Tank (300), - Solution 15 (172) of the condensed water formed as a result of the evaporation process To recover the Tank (300), - Circulating the process water within the system in a closed loop, A water recovery method characterized by its inclusion.

5. A method that conforms to claim 1 and its characteristic is that sodium sulfate solution (301) 20 its concentration depends on the amount of sodium sulfate and polyhalite in the ore. It is the adjustment.

6. A method that complies with Claim 1, characterized by the pelleting process of the polyhalite product. It is converted into granular fertilizer form (161). 25 7. A method that complies with Claim 1, characterized by the leaching process being carried out at a temperature of 15-50°C. It should be performed within this range and for a duration of 3-30 minutes.

8. A method that complies with Claim 1, characterized by the fact that 30 oz are transferred to the leaching tank after the crushing process. (130) The feed ore should have a particle size range of 20-50 mm.

9. A method that conforms to Claim 1 and its characteristic is that the sodium sulfate solution (301) is 2-25%. It is prepared in the concentration range.

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