Enrichment of sodium sulfate-containing materials

Abstract

A method of enriching a sodium sulfate-containing material includes treating the sodium sulfate-containing material and potassium chloride and forming potassium sulfate, i.e., a sulfate of potash (SOP), as a marketable product.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims priority to U.S. Provisional Application No. 63 / 406,707, filed on September 14, 2022. Technical Field

[0003] The present disclosure relates to beneficiating materials containing sodium sulfate and producing marketable products.

[0004] The present disclosure specifically relates to (but is not limited to) beneficiating waste materials containing sodium sulfate and producing marketable products.

[0005] The present disclosure also specifically relates to (but is not limited to) a method for producing potassium sulfate, i.e., sulfate of potash (SOP), from materials containing sodium sulfate (such as waste materials containing sodium sulfate).

[0006] The present disclosure also specifically relates to (but is not limited to) beneficiating materials containing sodium sulfate (such as waste materials containing sodium sulfate) and producing SOP, and using SOP to produce fertilizer products containing SOP and boron, herein referred to as SOP + B fertilizer products.

[0007] The present disclosure also specifically relates to (but is not limited to) equipment for producing fertilizer products containing potassium sulfate (sulfate of potash or "SOP") and boron, wherein the potassium sulfate is produced by beneficiating materials containing sodium sulfate (such as waste materials containing sodium sulfate). Background Art

[0008] The following description focuses on materials containing sodium sulfate that are considered waste.

[0009] The present invention is not limited to waste materials containing sodium sulfate, but extends to any material containing sodium sulfate.

[0010] Sodium sulfate is part of the by-products of many industrial processes, including processes for producing borates and / or lithium from borate minerals, lithium-containing minerals, and borate / lithium-containing minerals, and processes for producing boric acid from borate minerals.

[0011] Sodium sulfate can be part of emissions or tailings streams from industrial processes and is typically contained in storage ponds and tailings dams of these operations. Sodium sulfate can be part of any other suitable waste stream containing sodium sulfate from industrial processes.

[0012] Although sulfate ions are not considered harmful, in some jurisdictions, there are sulfate restrictions on the disposal of sulfates to reduce environmental stress caused by increased salt concentrations in natural waters (especially fresh water).

[0013] The applicant has developed a method for enriching a sodium sulfate-containing waste stream from a waste source containing sodium sulfate and producing marketable potassium sulfate (i.e., sulfate of potash (SOP)).

[0014] It is understood that the above description should not be regarded as an admission of common general knowledge anywhere. Summary of the Invention

[0015] The present disclosure provides a method for enriching a material containing sodium sulfate, the method comprising treating a material containing sodium sulfate and potassium chloride and forming potassium sulfate (i.e., sulfate of potash (SOP)) as a marketable product.

[0016] The term "marketable product" is understood herein to refer to a product that can be sold on the market. The term "marketable product" is understood herein to include SOP that can be sold on the market as a fertilizer or as a raw material for producing fertilizer products.

[0017] The present disclosure also provides a method for producing potassium sulfate, i.e., sulfate of potash (SOP), the method comprising treating a material containing sodium sulfate and potassium chloride and forming SOP.

[0018] The material containing sodium sulfate can be a sodium sulfate-containing material regarded as waste.

[0019] The material containing sodium sulfate can be obtained from any suitable sodium sulfate-containing material, including any suitable waste source containing sodium sulfate.

[0020] By way of example, the waste source can be a mineral processing operation, such as a borate production process, a lithium production process, a borate / lithium production process, and a boric acid production process.

[0021] The waste source can be existing storage ponds and tailing dams of the above operations.

[0022] The method can comprise treating a material containing sodium sulfate (such as a sodium sulfate-containing waste) and potassium chloride in the glaserite process and forming SOP.

[0023] The glaserite process is a two-stage process for converting sodium sulfate to potassium sulfate, and the following reactions (1) and (2) occur in stages 1 and 2 respectively:

[0024] (1)

[0025] (2)

[0026] In stage 1, sodium sulfate reacts with KCl according to reaction (1) under conditions close to ambient temperature, and a reaction slurry containing glaserite solid (K3Na(SO4)2) and a soluble sodium chloride solution is produced.

[0027] In stage 2, glaserite solid and KCl solution are blended together and reacted according to reaction (2) at near ambient temperature to produce a reaction slurry containing potassium sulfate (SOP) solid. The SOP solid is separated from the slurry and dried to produce a dry powder product.

[0028] The present disclosure also provides an SOP + B fertilizer product that provides macronutrients and micronutrients.

[0029] The SOP + B fertilizer product of the present disclosure allows farmers to use a single fertilizer product to correct deficiencies of potassium and sulfur in the soil while providing sufficient amounts of boron for plant growth in crops.

[0030] The exact amount of boron in the fertilizer product can be selected according to the plant's boron requirements in the crop.

[0031] According to the present disclosure, there is also provided a fertilizer product comprising (a) potassium sulfate (sulfate of potash or "SOP") produced from a source of material containing sodium sulfate and potassium chloride; and (b) boron, wherein the amount of boron is equivalent to 0.2 wt% to 3.0 wt% of B.

[0032] The material containing sodium sulfate can be a material containing sodium sulfate that is considered waste.

[0033] The amount of boron in the fertilizer product can be equivalent to more than 0.5 wt% of B.

[0034] The amount of boron in the fertilizer product can be equivalent to more than 0.6 wt% of B.

[0035] The amount of boron in the fertilizer product can be equivalent to more than 0.9 wt% of B.

[0036] The amount of boron in the fertilizer product can be equivalent to no more than 10 wt% of B.

[0037] The amount of boron in the fertilizer product can be equivalent to no more than 7 wt% of B.

[0038] The amount of boron in the fertilizer product can be equivalent to no more than 1.75 wt% of B.

[0039] The amount of boron in the fertilizer product can be equivalent to no more than 1.5 wt% of B.

[0040] The amount of boron in the fertilizer product can be 5 wt% to 7 wt% of B.

[0041] The fertilizer product can contain boron in any one or more of the boron-containing compounds boric acid, borax pentahydrate, borax anhydrous, boron oxide, kernite, ulexite, borax decahydrate, zinc borate, ulexite, and disodium octaborate tetrahydrate (DOT), or a combination thereof.

[0042] The fertilizer product may also contain micronutrients in addition to boron.

[0043] The fertilizer product may also contain additional micronutrients selected from the group consisting of iron, molybdenum, cobalt, manganese, nickel, copper, zinc, or combinations thereof.

[0044] The additional micronutrient can be any suitable micronutrient, such as zinc.

[0045] The form of zinc can be zinc acetate, zinc fluoride, zinc bromide, zinc nitrate, zinc chloride, zinc iodide, zinc oxide, zinc permanganate, zinc sulfate heptahydrate, zinc sulfate monohydrate, zinc sulfite, zinc tartrate, zinc oxysulfate, zinc EDTA, and zinc ammonium salts.

[0046] The additional micronutrient can be any one of the following micronutrients in the following forms:

[0047] 1) Micronutrient iron: iron(II) carbonate, iron(II) nitrate, iron(II) chloride, iron(II) hydroxide, iron(II) oxalate, iron(II) sulfate, iron(III) chloride, iron(III) fluoride, iron(III) hydroxide, iron(III) nitrate, iron(III) sulfate, iron EDTA.

[0048] 2) Micronutrient manganese: manganese(II) bromide, manganese(II) carbonate, manganese(II) chloride, manganese(II) hydroxide, manganese(II) nitrate, manganese(II) fluoride, manganese(II) oxalate, manganese(II) sulfate, manganese oxy-sulfate, manganese EDTA.

[0049] 3) Micronutrient copper (usually not required): copper(I) chloride, copper(I) hydroxide, copper(I) iodide, copper(I) sulfide, copper(I) oxide, copper(II) fluoride, copper(II) bromide, copper(II) carbonate, copper(II) chloride, copper(II) hydroxide, copper(II) nitrate, copper(II) oxide, copper oxalate, copper(II) sulfate, copper(II) sulfide, copper EDTA.

[0050] 4) Micronutrient molybdenum: ammonium molybdate, molybdenum trioxide, molybdenum disulfide, calcium molybdate, magnesium molybdate.

[0051] 5) Micronutrient nickel: nickel sulfate, nickel bromide, nickel carbonate, nickel chloride, nickel fluoride, nickel formate, nickel hydroxide, nickel iodide, nickel nitrate, nickel oxalate, nickel sulfate.

[0052] 6) Micronutrient cobalt (usually not required): cobalt(II) fluorosilicate, cobalt(II) iodide, cobalt(II) nitrate, cobalt(II) nitrite, cobalt(II) oxalate, cobalt(II) sulfate, cobalt(II) chloride, cobalt(II) bromide, cobalt(II) fluoride.

[0053] The fertilizer product may contain macronutrients in addition to potassium and sulfur.

[0054] The additional macronutrients may be any of the following macronutrients in the following forms:

[0055] 1) Phosphorus-containing macronutrients: super phosphate, concentrated super phosphate, monoammonium phosphate, diammonium phosphate, ammonium polyphosphate, phosphoric acid, phosphorous acid, phosphonic acid, bone ash, bone meal, phosphate rock.

[0056] 2) Macronutrient magnesium: magnesium acetate, magnesium bromide, magnesium carbonate, magnesium chloride, magnesium formate, magnesium hydroxide, magnesium fluoride, magnesium iodide, magnesium nitrate, magnesium oxalate, magnesium oxide, magnesium phosphate, magnesium sulfate, magnesium sulfite, magnesium thiosulfate, magnesium selenite.

[0057] 3) Macronutrient calcium: calcium acetate, calcium benzoate, calcium bicarbonate, calcium bromide, calcium carbonate, calcium fluoride, calcium chloride, calcium citrate, monocalcium phosphate, calcium formate, dicalcium phosphate, calcium hydroxide, calcium iodide, calcium nitrate, calcium nitrite, calcium oxalate, calcium oxide, calcium phosphate, calcium selenite, calcium sulfate.

[0058] The fertilizer product may be in the form of granules or pellets.

[0059] The term "granule" is understood herein to refer to small, compact particles of a material, the shape of which may be regular or irregular.

[0060] Granules can be formed by agglomeration, compaction or other means and can subsequently be further comminuted.

[0061] The term "pellet" is understood herein to refer to particles of a material that suitably have a regular shape. Pellets can be formed by compression, compaction, molding or other means.

[0062] Granules or pellets can be formed to provide the mechanical properties required for handling the materials for the granules or pellets.

[0063] Granules or pellets can be compacted in a compaction or dry granulation process.

[0064] Alternatively, other granulation methods can also be used, such as wet granulation in a disk or other suitable pelletizer or fluidized bed or high-energy mixing granulator, to compact the granules or pellets.

[0065] The size of the granules or pellets can be from 1 mm to 5 mm, usually from 2 mm to 4 mm.

[0066] The fertilizer product can be a slow - release product.

[0067] The term "slow - release" is understood herein to mean that the release of nutrients in the soil occurs gradually over a period of time, since the nutrients are in a form that is not readily taken up by the plants in the crop until some time has passed after the fertilizer is applied.

[0068] The fertilizer product can be a controlled - release product.

[0069] The term "controlled - release" is understood herein to mean that the release of nutrients in the soil is controlled to match the dynamic needs of the crop. Controlled - release fertilizers typically contain water - soluble nutrients coated or encapsulated with materials that control the rate of release of the nutrients in the crop. The coating is usually a semi - permeable material that can control the rate, pattern, and duration of nutrient release.

[0070] The fertilizer product can include granules or pellets, and a coating for controlling the release of macronutrients and micronutrients in the granules or pellets.

[0071] The coating can be made of any suitable material.

[0072] The coating can be made of polymeric materials.

[0073] The coating can be made of sulfur - containing polymeric materials.

[0074] The coating can include any one of the following materials.

[0075] - Inorganic materials: bentonite, phosphogypsum, gypsum, hydroxyapatite, zeolite, sepiolite.

[0076] - Synthetic polymers: polyurethane, polyethylene, polyacrylamide, polycaprolactone, polystyrene, polysulfone, aliphatic polyester, polyvinyl alcohol, bio - based epoxy resin.

[0077] - Natural polymers: starch, cellulose, chitosan, ethyl cellulose, carboxymethyl cellulose, hydroxymethyl cellulose, hydroxypropyl methyl cellulose, bio - based polyurethane, polysulfone, latex, natural rubber, lignin, alginate.

[0078] - Hydrophobic sealants: paraffin, polyol.

[0079] The coating can be formed by any one of the following coating techniques: drum coating, pan coating, fluidized bed coating, melt and extrusion coating, solution polymerization and cross - linking, inverse suspension polymerization, and microwave irradiation.

[0080] The fertilizer product can also contain adhesives.

[0081] The binder can be any suitable material.

[0082] The binder can be starch.

[0083] The binder can be water.

[0084] According to the present disclosure, there is also provided a method for producing a fertilizer product, comprising:

[0085] (a) blending (i) potassium sulfate (sulfate of potash or "SOP") produced from a source of material containing sodium sulfate and potassium chloride and (ii) one or more boron-containing compounds together, for example by dry blending or wet blending; and

[0086] (b) forming the blended potassium sulfate and one or more boron-containing compounds into granules or pellets by compaction, agglomeration or other means.

[0087] Water can be added during the blending step (a).

[0088] The material containing sodium sulfate can be a material containing sodium sulfate regarded as waste.

[0089] The potassium chloride can be obtained from any suitable source.

[0090] When the blending step (a) is a dry blending step, the method can include adding up to 30% by weight of moisture before the forming step (b). Suitably, the method includes adding up to 20% by weight of moisture before the forming step (b). More suitably, the method includes adding up to 10% by weight of moisture before the forming step (b). Even more suitably, the method includes adding up to 2% by weight of moisture before the forming step (b).

[0091] When the blending step (a) is a wet blending step, the method can include drying the blended potassium sulfate and one or more boron-containing compounds before the forming step (b) to form a mixture having a moisture content not exceeding 30% by weight. Suitably, the method includes drying the blended potassium sulfate and one or more boron-containing compounds before the forming step (b) to form a mixture having a moisture content not exceeding 20% by weight. More suitably, the method includes drying the blended potassium sulfate and one or more boron-containing compounds before the forming step (b) to form a mixture having a moisture content not exceeding 10% by weight. Even more suitably, the method includes drying the blended potassium sulfate and one or more boron-containing compounds before the forming step (b) to form a mixture having a moisture content not exceeding 2% by weight.

[0092] The method can include drying the granules or pellets.

[0093] The SOP and one or more boron-containing compounds may be dry powders.

[0094] The method may include producing SOP from a sodium sulfate-containing material (such as sodium sulfate-containing waste) by the above method.

[0095] SOP may be produced by the glaserite process.

[0096] The method may include providing sodium sulfate waste and potassium chloride as feeds for the glaserite process and forming SOP.

[0097] One or more boron-containing compounds may be selected from any one or more of boric acid, borax pentahydrate, borax anhydrous, boron oxide, borax tetrahydrate, ulexite, borax decahydrate, zinc borate, orthoborax, and disodium octaborate tetrahydrate (DOT), or a combination thereof.

[0098] The blending step (a) may include mixing a binder with potassium sulfate and one or more boron-containing compounds.

[0099] The binder may be starch.

[0100] The binder may be water.

[0101] The blending step (a) may be a batch blending step, i.e., the compounds are added together simultaneously and then blended together.

[0102] The blending step (a) may include adding and mixing the compounds in any suitable order.

[0103] The method may include crushing the pellets or agglomerates produced in the pellet / agglomerate formation step (b).

[0104] The method may include sizing (e.g., screening) the crushed pellets or agglomerates and separating the sized pellets or agglomerates according to size to produce a product fraction.

[0105] The method may include sizing (e.g., by screening) the crushed pellets or agglomerates into an oversized fraction, a product fraction, and an undersized fraction.

[0106] The product fraction may be any suitable size fraction.

[0107] The product fraction may be at least 1 mm.

[0108] The product fraction may be at least 2 mm.

[0109] The product fraction may not exceed 6 mm.

[0110] The product fraction may not exceed 5 mm.

[0111] The product fraction may not exceed 4 mm.

[0112] The product fraction may be a fraction having a size of 1 - 4 mm.

[0113] The product fraction may be a fraction having a size of 1 - 5 mm.

[0114] The product fraction may be a fraction having a size of 1 - 6 mm.

[0115] The method may include returning the oversized fraction to the comminution step.

[0116] The method may include returning the undersized fraction to the pellet / agglomerate forming step (b).

[0117] The method may include drying the product fraction to form a fertilizer product.

[0118] The present disclosure also provides a method for producing a fertilizer product comprising potassium sulfate (sulfate of potash or "SOP") and boron, the method comprising:

[0119] (a) blending (i) SOP produced from a sodium sulfate material source such as a sodium sulfate waste source and potassium chloride, and (ii) one or more boron-containing compounds and optionally other micronutrients,

[0120] (b) forming the blend into pellets or agglomerates by compaction or other means,

[0121] (c) sizing the pellets or agglomerates by screening or other means to produce a product fraction, and

[0122] (d) drying the pellets or agglomerates in the product fraction to form a fertilizer product.

[0123] Water may be added during the blending step (a).

[0124] The method may include comminuting the pellets or agglomerates produced in the pellet / agglomerate forming step.

[0125] The sizing step (c) may include producing an oversized fraction, an undersized fraction, and a product fraction.

[0126] The method may include a comminution step after the sizing step (c). Suitably, the method includes returning the comminuted material to the blending step after the screening step. The comminuted material may include any one or a mixture of comminuted oversized material and undersized material.

[0127] The method may include returning the oversized fraction to the pellet / agglomerate forming step (b).

[0128] The method may include returning the undersized fraction to the compaction step.

[0129] The present disclosure also provides an apparatus for producing a fertilizer product comprising potassium sulfate (sulfate of potash or "SOP") and boron, the apparatus comprising:

[0130] (a) an SOP production unit for producing SOP from a sodium sulfate material source such as a sodium sulfate waste source and potassium chloride,

[0131] (b) a blending unit for blending (i) the SOP produced by the SOP production unit (a) and (ii) one or more boron-containing compounds and optionally other micronutrients,

[0132] (c) a compaction unit or other suitable unit for forming the blend into granules or pellets,

[0133] (d) a screening unit or other sizing unit for screening the granules and pellets to produce a product fraction; and

[0134] (e) drying the granules or pellets in the product fraction to form a fertilizer product.

[0135] The SOP production unit (a) may be a glaserite process unit.

[0136] The apparatus may include a grinding unit for grinding the granules or pellets produced in the compaction unit or other suitable granule / pellet forming unit.

[0137] The grinding unit may be used to grind the compacted material from the compaction unit or other suitable granule / pellet forming unit (c). BRIEF DESCRIPTION OF THE DRAWINGS

[0138] The present disclosure will be further described by way of examples with reference to the accompanying drawings:

[0139] Figure 1 is a flow chart showing an embodiment of a method and apparatus for producing an SOP + B fertilizer product according to the present disclosure;

[0140] Figure 2 is a flow chart showing another embodiment of a method and apparatus for producing an SOP + B fertilizer product according to the present disclosure;

[0141] Figure 3 is a flow chart showing another (but not the only other) embodiment of a method and apparatus for producing an SOP + B fertilizer product according to the present disclosure; and

[0142] Figure 4 is a flow chart showing an embodiment of a granulation method and Figure 1 the apparatus according to the present disclosure. DETAILED DESCRIPTION

[0143] Figure 1 is a process flow diagram of one (but not the only) embodiment of the method and apparatus of the present disclosure.

[0144] The flow chart is as Figure 1 shown:

[0145] (a) Enrich the sodium sulfate-containing material (in this example, the sodium sulfate-containing waste), by treating the sodium sulfate-containing waste stream and potassium chloride in the kainite process, and forming potassium sulfate, i.e., sulfate of potash (SOP), and

[0146] (b) Produce a fertilizer product from the SOP produced in the above stage (a), which is used as a micronutrient-rich fertilizer, a general fertilizer, or a crop nutrient in soil applications.

[0147] Referring to Figure 1 , the feed of the method is the mother liquor slip stream 3 from a boric acid plant (BAP) (not shown).

[0148] The BAP mother liquor slip stream 3 contains sodium sulfate, boric acid, and other impurities, and the concentration of boric acid depends on the composition of the borate ore and the temperature for recovering boric acid.

[0149] It should be noted that the present disclosure is not limited to obtaining sodium sulfate from the BAP mother liquor slip stream 3. However, using the sodium sulfate from this source is a useful end use of the BAP mother liquor slip stream 3, otherwise it would be a waste stream in the BAP.

[0150] The present disclosure can be extended to using a sodium sulfate-containing waste stream from any suitable sodium sulfate-containing waste source.

[0151] The present disclosure can also be extended to using a sodium sulfate-containing stream from any suitable sodium sulfate-containing material source that is not necessarily a sodium sulfate-containing waste stream.

[0152] The feed 3 is transferred to a sodium sulfate recovery unit 7 to form a sodium sulfate concentrate 5 and a boric acid (BA) solution 9.

[0153] The sodium sulfate recovery unit 7 can be any suitable unit. Examples of suitable units include reverse osmosis (RO) and / or nanofiltration membrane units, evaporators, and crystallizers.

[0154] The boric acid (BA) solution 9 is recycled to the BAP.

[0155] The sodium sulfate concentrate 5 is transferred to a sulfate mother liquor preparation unit 15.

[0156] Sodium sulfate concentrate 5, water 11, Glauber's salt (sodium sulfate decahydrate or Na2SO4·10H2O) 13, and sodium sulfate solution 45 are mixed together in unit 15 to produce a sodium sulfate mother liquor (ML) 17. For example, the sulfate mother liquor preparation unit 15 is a mixing tank.

[0157] The Glauber's salt stream comes from a lithium plant (not shown). Otherwise, the Glauber's salt stream would be processed in a pond. The present disclosure is not limited to this source of Glauber's salt.

[0158] The sodium sulfate solution 45 comes from a downstream step in the method. The present disclosure is not limited to this source of sodium sulfate.

[0159] The sodium sulfate ML 17 is transferred to a polishing filtration unit 19 or any other suitable unit to remove solid impurities and produce a product stream 21 containing sodium sulfate in solution and a solid filter cake 23.

[0160] The filter cake 23 is a waste product.

[0161] The sodium sulfate product stream 21 is converted to potassium sulfate through a two-stage glaserite reaction. The following reactions (1) and (2) occur in stages 1 and 2, respectively:

[0162] (1)

[0163] (2)

[0164] In stage 1, the sodium sulfate stream 21 reacts with potash (KCl) 27, water 29, and potassium concentrate 87 in reactor 25 at near ambient temperature according to reaction (1) to produce a reaction slurry (S1) 31 containing glaserite solid (K3Na(SO4)2) and a soluble sodium chloride solution.

[0165] The reaction slurry 31 from stage 1 is transferred to a solid-liquid separation unit 33, which recovers the glaserite solid in the form of a glaserite cake 37 and produces a glaserite solution 39.

[0166] For example, the solid-liquid separation unit 33 can be a centrifugation step that separates the glaserite cake 37 from the slurry 31 using wash water 35.

[0167] The glaserite solution 39 contains soluble sodium chloride and is processed in an NaCl recovery unit 41 and a sodium chloride separation unit 43 to produce a solid sodium chloride cake 91 and the above-mentioned sodium sulfate solution 45. The sodium sulfate solution 45 is transferred to the sulfate mother liquor preparation unit 15 or processed in a pond or other treatment options.

[0168] The NaCl recovery unit 41 may include, but is not limited to, an evaporation crystallization step for precipitating the NaCl solute, with or without a previous sulfate separation step via a membrane, to produce a sodium sulfate concentrate that can be used in the sulfate mother liquor preparation unit or elsewhere in the method. Other suitable techniques alternative to the crystallization step may include reverse osmosis and / or nanofiltration steps.

[0169] The langbeinite cake 37 produced in the solid-liquid separation unit 33 is transferred to the SOP reactor 51.

[0170] The langbeinite cake 37 and the KCl solution 53 are mixed together and reacted in the SOP reactor 51 at near ambient temperature according to reaction (2) to produce a reaction slurry (S2) 55, which contains potassium sulfate (SOP) solids and a solution mainly containing potassium chloride (excess KCl added in stage 2), sulfates, and trace amounts of NaCl from the reaction.

[0171] In this embodiment, the KCl solution 53 is prepared by mixing potash 57 in dry solid form with water 59 in a mixing tank 61.

[0172] The SOP solids are separated from the reaction slurry 55 in the solid-liquid separation unit 63.

[0173] For example, the solid-liquid separation unit 63 is a centrifugation step. Washing water 99 is provided to separate the solids from the reaction slurry 55, producing an output SOP cake 65 and a centrifugate 81. The centrifugate 81 contains a high concentration of potassium and a large but much lower amount of NaCl.

[0174] Other types of solid-liquid separation units may be used.

[0175] The centrifugate 81 is transferred to a potassium solution concentration unit 85, for example, concentrated by evaporation to produce a potassium concentrate 87, which is supplied to the reactor 25 to facilitate the langbeinite reaction, thereby maximizing the potassium yield. The steam 91 generated in the concentration unit 85 can be used in multiple units of the SOP production method or elsewhere.

[0176] Other suitable techniques alternative to the evaporation step may include reverse osmosis, which can concentrate our potassium stream to a sufficient extent to recycle it back to stage 1.

[0177] The SOP cake 65 produced in the solid-liquid separation unit 63 is dried in a dryer 67 (such as a rotary dryer) to form a dry SOP powder product 69 and steam 97.

[0178] The method of using glaserite to produce SOP has advantages because, as described above, waste streams containing sodium sulfate are typically generated in mineral processing operations (such as borate / lithium production operations and boric acid production operations) and are sources of waste that must be stored in ponds, tailings dams or otherwise disposed of by the mine operator.

[0179] Currently, the market for sodium sulfate is limited, while large amounts of sodium sulfate are generated in mineral processing operations.

[0180] The source of sodium sulfate waste is readily available on-site - either as a waste stream generated as part of a continuous process operation or as waste stored in ponds and tailings dams.

[0181] Thus, the use of sodium sulfate waste in the present disclosure may bring potential benefits to the mine operator.

[0182] In addition, compared with other options such as using the Manheim process (i.e., H2SO4 + KCl) to produce sodium sulfate or purchasing sodium sulfate from other sources, the use of sodium sulfate waste is an opportunity to reduce the production cost of SOP.

[0183] Figure 2 is a flow chart showing another embodiment of a method and apparatus for producing SOP + B fertilizer products.

[0184] Figure 3 is a flow chart showing another (but not the only other) embodiment of a method and apparatus for producing SOP + B fertilizer products.

[0185] Figures 1 - 3 The same reference numerals are used in to describe the same features.

[0186] Figures 1 - 3 The flow charts in are substantially the same, and the differences between the flow charts will be highlighted below.

[0187] In Figure 2 the flow chart of, the sodium sulfate recovery unit 7 is shown as a membrane unit.

[0188] In addition, the glaserite solution 39 generated in the solid-liquid separation unit 33 is processed in the sodium sulfate separation unit 85 in the form of a membrane unit, and a sodium sulfate concentrate 47 and a chlorine-containing permeate 49 are produced.

[0189] The sodium sulfate concentrate 47 is transferred to the sodium sulfate solution 45 and becomes part of the sodium sulfate solution 45, while the sodium sulfate solution 45 is transferred to the sulfate mother liquor preparation unit 15.

[0190] The permeate 49 is transferred to the NaCl recovery unit 41 (in the form of a membrane unit in this embodiment) and the sodium chloride separation unit 43, and in accordance withFigure 1 Perform the processing as described.

[0191] Figure 3 The flow chart is the same as Figure 2 the flow chart, except that the NaCl recovery unit 41 is in the form of an evaporation crystallizer rather than Figure 2 the form of the membrane unit in the flow chart.

[0192] Further referring to Figures 1 - 3 , the dried SOP powder product 69 is a marketable product.

[0193] In Figures 1 - 3 the embodiment, the dried SOP powder product 69 is used to produce a fertilizer product, as described below.

[0194] The dried SOP powder product 69 can also be used as a soluble fertilizer, fine potassium sulfate, and / or for producing granular fertilizer products.

[0195] Figures 1 - 3 The fertilizer product produced in the embodiment contains SOP and boron, where the amount of boron is equivalent to 0.2 wt% to 3.0 wt% of B.

[0196] Generally, Figures 1 - 3 the formulated fertilizer product produced in the embodiment contains SOP and boron, where the amount of B is equivalent to 0.2 wt% to 3.0 wt% of B, which is selected according to the demand of the target crop for B.

[0197] Figures 1 - 3 The formulated fertilizer product produced in the embodiment may also contain other materials, including other micronutrients and binders.

[0198] In the agricultural fertilizer industry, an important consideration is that the fertilizer product should contain a minimum amount of materials that are not beneficial to the fertilizer (such as starch binders). Therefore, the formulated fertilizer product contains a minimum amount of such other materials.

[0199] Broadly speaking, Figures 1 - 3 the fertilizer production part of the method shown includes:

[0200] (a) Blending the dried SOP powder product 69 and one or more boron-containing compounds together,

[0201] (b) Compacting the blend into granules or pellets; and

[0202] (c) Crushing, screening, and drying the granules or pellets to form a fertilizer product.

[0203] Figure 1 The product formulation produced in the process flow chart is in the form of compacted granules with a particle size of 1 - 5 mm (usually 2 - 4 mm).

[0204] Reference Figure 1 In the granulation device 77, the dry SOP powder product 69 is combined with a boron-containing compound 71, water 73, an optional binder 75, and optionally other additional micronutrients to form granules of the SOP+B final product 79.

[0205] The steam 97 generated in the rotary dryer 67 can be used in multiple units of the SOP production method or elsewhere.

[0206] Figure 4 is a process flow diagram showing the steps in an embodiment (although not the only embodiment) of the granulation device 77 according to the present disclosure.

[0207] The method steps for forming the dry SOP powder product 69 transferred to the granulation device 77 are the same as those Figure 1 described in, and are substantially the same as the method steps described in Figure 2 and Figure 3 and will not be repeated here. It should be noted that Figure 1 and Figure 4 the same reference numerals are used in and to describe the same features.

[0208] Figure 4 The key features of the embodiment of the method for producing a fertilizer product shown are the formulation and compaction of the SOP+B product.

[0209] Further reference is made to Figure 4 The granulation device 77 includes a bulk blending unit 103 that mixes the dry SOP powder product 69, the boron-containing compound 71, water 75, an optional binder 75, and optionally other micronutrients selected from the above list in a target ratio based on the B nutrient crop requirement to produce a blended product 105.

[0210] The blended product 105 is compacted and dried in the compaction unit 107 to form granules or pellets 109. The target size of the granules or pellets 109 in the final fertilizer product is 1 - 5 mm, typically 2 - 4 mm.

[0211] The granules or pellets 109 are pulverized in the pulverizer unit 111 to produce pulverized granules or pellets 113.

[0212] The pulverized granules or pellets 113 are transferred to the screening unit 115 and separated into an oversized fraction 119, an undersized fraction 117, and a product fraction 121.

[0213] The undersized fraction 117 is returned to the compaction unit 107 and reprocessed.

[0214] Return the oversized fraction 119 to the grinder unit 111 and re-grind it.

[0215] The product fraction 121 is particles or pellets of the target size and is transferred to the dryer unit 123 and dried to form the final fertilizer product 125.

[0216] Numerous modifications may be made to the above-described embodiments without departing from the spirit and scope of the invention.

[0217] For example, although Figure 4 the embodiments shown include boron micronutrients, the present disclosure is not limited thereto and may be extended to other additional micronutrients. For example, the micronutrients may be selected from the group consisting of iron, molybdenum, cobalt, manganese, copper, nickel, zinc, or combinations thereof.

[0218] For another example, although Figure 4 the embodiments shown are compaction or dry granulation methods, the present disclosure is not limited thereto and may be extended to other granulation methods. For example, the method may include wet granulation in a disc or other suitable pelletizer or fluidized bed or high-energy mixing granulator.

[0219] In Figure 2 the embodiments, the particles or pellets may be slow-release particles. For another example, Figure 2 the embodiments of the method shown may include coating the particles or pellets with a quick-release coating.

[0220] The applicant has carried out development work on the above invention to better determine how to implement the present invention on a large scale in an efficient manner.

[0221] The applicant has conducted bench-scale (1L) tests and batch pilot-scale tests (30L batch) to produce SOP from sodium waste (Glauber's salt) generated on-site at a lithium production plant. The tests have shown that it is feasible to produce a product with greater than 95% K2SO4 using a two-stage glaserite process under conditions close to ambient temperature, and that in stage 1, the minimum KCl addition ratio is 0.79 g KCl / g Na2SO4, and in stage 2, the minimum KCl addition ratio is 0.70 g KCl / g glaserite. By testing different parameters in the bench-scale tests, the optimal reaction time and reagent concentration in the reaction slurry have also been determined.

[0222] It will be understood that if any prior art publications are cited herein, such citations do not represent an admission that such publication forms part of the common general knowledge in the art in Australia or any other country.

[0223] In the appended claims of the present invention and the preceding specification, unless the context otherwise requires due to the language of expression or necessary implication, the word "comprise" or variants such as "comprises" or "comprising" are used in an inclusive sense, that is, to indicate the presence of the specified features, but not to exclude the presence or addition of further features in the various embodiments of the present invention.

Claims

1. A method for enriching a material containing sodium sulfate, comprising treating the material containing sodium sulfate and potassium chloride, and forming potassium sulfate, i.e., sulfate of potash (SOP), as a marketable product.

2. A method for producing potassium sulfate, i.e., sulfate of potash (SOP), comprising treating the material containing sodium sulfate and potassium chloride, and forming SOP.

3. The method as defined in claim 1 or 2, wherein the material containing sodium sulfate includes waste materials.

4. The method as defined in claim 3, wherein the waste materials containing sodium sulfate are obtained from any one or more of a borate production process, a lithium production process, a borate / lithium production process, and a boric acid production process.

5. The method as defined in any one of the preceding claims, comprising treating the material containing sodium sulfate and potassium chloride in the glaserite process, and forming SOP.

6. A fertilizer product, comprising (a) potassium sulfate (sulfate of potash or "SOP") produced from a material containing sodium sulfate and potassium chloride; and (b) boron, wherein the amount of boron is equivalent to 0.2 wt% to 3.0 wt% of B.

7. A method for producing a fertilizer product, comprising: (a) blending (i) potassium sulfate (sulfate of potash or "SOP") produced from a material containing sodium sulfate and potassium chloride and (ii) one or more boron-containing compounds and optionally one or more other micronutrients by dry blending or wet blending; and (b) forming the blended potassium sulfate and one or more boron-containing compounds into granules or pellets by compaction, agglomeration or other means.

8. The method as defined in claim 7, comprising crushing the granules or pellets formed by compaction or other means.

9. The method as defined in claim 8, comprising sizing the crushed granules or pellets, such as by screening, and separating the crushed granules or pellets according to size to form a product fraction.

10. The method as defined in claim 9, comprising sizing the crushed granules or pellets, such as by screening, into an oversized fraction, a product fraction, and an undersized fraction.

11. The method as defined in claim 10, comprising returning the oversized fraction to the crushing step.

12. A method for producing a fertilizer product containing potassium sulfate (sulfate of potash or "SOP") and boron, the method comprising: (a) blending (i) SOP produced from sodium sulfate material and potassium chloride with (ii) one or more boron-containing compounds and optionally other micronutrients; (b) forming the blend into granules or pellets by compaction or other means; (c) sizing the granules or pellets by screening or other means to form a product fraction; and (d) drying the granules or pellets in the product fraction to form the fertilizer product.

13. An apparatus for producing a fertilizer product containing potassium sulfate (sulfate of potash or "SOP") and boron, the apparatus comprising: (a) an SOP production unit for producing SOP from a sodium sulfate material source and potassium chloride; (b) a blending unit for blending (i) the SOP produced by the SOP production unit (a) and (ii) one or more boron-containing compounds and optionally other micronutrients; (c) Compacting unit or other unit for forming the blend into granules or pellets; (d) Screening unit for screening the granules and pellets to produce a product fraction; and (e) Drying unit for drying the granules or pellets in the product fraction to form the fertilizer product.

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