Filter aid

Abstract

The present disclosure relates to providing a filter aid wherein the filter aid comprises: a first composition comprising inorganic particles, the inorganic particles comprising silicon; and a second composition comprising a dicarboxylic acid or a dicarboxylic acid polymer. The present disclosure also describes methods of preparation and filtration.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to filter aids, wherein the filter aid comprises: a first composition comprising inorganic particles, said inorganic particles comprising silicon, and a second composition comprising a dicarboxylic acid or a polymer of a dicarboxylic acid. The present disclosure also relates to a method of filtering a liquid, a method of making a filter aid, and a method of preventing or reducing leaching of silicon from a filter aid. BACKGROUND

[0002] In liquid filtration processes where removal of fine particles or contaminants is desired, filter aids are used. Such filter aids are either added to the suspension to be filtered or placed as a layer on the filter through which the liquid has to pass.

[0003] Filter aids are typically constructed from inorganic particles such as diatomaceous earth or perlite, which have the advantage of being light weight, inert and almost insoluble in inorganic and organic acids at all temperatures.

[0004] However, it is known that unwanted elemental impurities such as silicon can leach from filter aids. Leaching of elemental impurities such as silicon is also undesirable in filtration processes, for example, in processes of filtering beverages or in other types of processes of filtering impurities from liquids such as aqueous solutions or hydrocarbons. The aqueous solutions and hydrocarbons can include oils, which include biofuels.

[0005] Extraction of unwanted impurities from aqueous solutions containing metals such as metal brines can also be achieved by using filter aid products. This is the case for example when extracting lithium from mined resources or from lithium rich brines. Lithium is highly desirable for the production of high performance lithium ion batteries. Extraction of other metals is also highly desirable. The use of filter aid products can be undesirable as they leach minerals such as silicon into the lithium brine which can create problems and can reduce the value of the brine.

[0006] Therefore, it is desirable to produce filter aids with improved impurity leachability. SUMMARY

[0007] According to some embodiments, there is provided a filter aid, wherein the filter aid comprises: a first composition comprising inorganic particles, said inorganic particles comprising silicon; and a second composition comprising a dicarboxylic acid or a polymer of a dicarboxylic acid.

[0008] According to some embodiments, there is provided a method of filtering a liquid or use of a filter aid for filtering a liquid, said method or use comprising contacting a filter aid according to the present disclosure with a liquid in order to filter unwanted particles from the liquid thereby forming a filtrate.

[0009] According to some embodiments, there is provided a method of filtering a liquid or use of a filter aid for filtering a liquid, the method or use comprising contacting a filter aid according to the present disclosure with a liquid so as to filter unwanted particles from the liquid to form a filtrate, wherein the first and second compositions can be added to the liquid in the following ways: i) simultaneously added to the liquid (either separately, or as a dry mixture or as a wet mixture or as a coated substrate, wherein the first composition is the substrate and the second composition is a coating on the substrate), or ii) sequentially added to the liquid in any order of addition.

[0010] According to some embodiments, there is provided a method of preventing or reducing leaching of silicon from a filter aid into a liquid during filtration, or use of a filter aid for preventing or reducing leaching of silicon into a liquid during filtration, the method or use comprising: mixing a first composition with a second composition to form a filter aid, and filtering a liquid with the filter aid to form a filtrate, wherein the first composition comprises inorganic particles, the inorganic particles comprising silicon, and wherein the second composition comprises a dicarboxylic acid or a dicarboxylic acid polymer.

[0011] According to some embodiments, there is provided a method of making a filter aid, comprising: mixing a first composition comprising inorganic particles, the inorganic particles comprising silicon, with a second composition comprising a dicarboxylic acid or a dicarboxylic acid polymer.

[0012] According to some embodiments, there is provided a filter aid, wherein the filter aid comprises: inorganic particles, the inorganic particles comprising silicon; and a coating selected from: a) an organic coating, wherein the organic coating comprises (i) a dicarboxylic acid; or (ii) a dicarboxylic acid polymer; b) an inorganic polymeric coating, wherein the inorganic polymeric coating comprises a halogenated metal polymer; and c) a combination of (a) and (b).

[0013] According to some embodiments, there is provided a method of preventing or reducing leaching of silicon from a filter aid into a liquid during filtration, the method comprising: coating inorganic particles with a coating to form a filter aid, and filtering a liquid with the filter aid to form a filtrate, wherein the inorganic particles comprise silicon; and wherein the coating is selected from: a) an organic coating, wherein the organic coating comprises (i) a dicarboxylic acid; or (ii) a dicarboxylic acid polymer; b) an inorganic polymeric coating, wherein the inorganic polymeric coating comprises a halogenated metal polymer; and c) a combination of (a) and (b).

[0014] According to some embodiments, there is provided a method of making a filter aid, comprising: coating inorganic particles with a coating, wherein the inorganic particles comprise silicon; and wherein the coating is selected from: a) an organic coating, wherein the organic coating comprises (i) a dicarboxylic acid; or (ii) a dicarboxylic acid polymer; b) an inorganic polymer coating, wherein the inorganic polymer coating comprises a halogenated metal polymer; and c) a combination of (a) and (b).

[0015] It will be understood by a person skilled in the art that features described in relation to any one aspect of the above can be adapted to any other aspect, mutatis mutandis, except where mutually exclusive. Furthermore, any feature described herein can be applied to any aspect described herein and / or in combination with any other feature, mutatis mutandis. DETAILED DESCRIPTION

[0016] It has been surprisingly found that by providing a coating on inorganic particles comprising silicon, leaching of silicon from a filter aid comprising the inorganic particles can be reduced or prevented. The coating is selected from a) an organic coating, wherein the organic coating comprises (i) a dicarboxylic acid; or (ii) a dicarboxylic acid polymer; b) an inorganic polymer coating, wherein the inorganic polymer coating comprises a halogenated metal polymer; and c) a combination of (a) and (b).

[0017] It has also been surprisingly found that leaching of silicon from a filter aid can be reduced or prevented, the filter aid comprising: a first composition comprising inorganic particles, the inorganic particles comprising silicon; and a second composition comprising a dicarboxylic acid or a dicarboxylic acid polymer. The filter aid can comprise a mixture of the first composition and the second composition. The filter aid can be a dry mixture or a wet mixture of the first composition and the second composition. The first composition of the filter aid can be a substrate and the second composition of the filter aid can be a coating on the first composition.

[0018] Inorganic particles The inorganic particles comprise or consist of diatomite, perlite, expanded perlite, expanded ground perlite, sand, bentonite, silica gel, kaolinite, zeolite, silicoaluminophosphate molecular sieve, or a mixture thereof. All of these inorganic particles comprise silicon.

[0019] Diatomite (DE) is derived from the remains of microscopic fossil-like marine or freshwater algae. DE is typically used as a filter aid. DE is known for its complex and porous structure, which is effective in trapping particles during filtration.

[0020] The DE starting material can be in the form of a crude DE or can have been subjected to one or more processing steps such as physical or chemical modification. Physical modification processes include, but are not limited to, grinding, drying, and air classifying. Chemical modification processes include, but are not limited to, silanization. Such modification processes are used to make the surface of the DE more hydrophobic or hydrophilic using methods such as those described in US 3,915,735 and US 4,260,498, the contents of which are incorporated herein by reference in their entirety.

[0021] The DE typically contains about 80% to 90% silica, 2% to 4% alumina (mainly due to clay minerals), and 0.5% to 2% iron oxide. The types of DE available are well known to those skilled in the art.

[0022] Unless otherwise specified, all inorganic particles described herein have the particle size properties mentioned herein measured by methods employed in the field of laser scattering using a CILAS 1064L particle size analyzer supplied by CILAS (or by other methods that give essentially the same results). In laser scattering techniques, laser beam diffraction can be used to measure the size of particles in powders, suspensions, and emulsions based on the application of Fraunhofer and Mie theories. This machine is capable of measuring and plotting the cumulative volume percentage of particles having a size less than a given e.s.d value, which is referred to in the art as the “equivalent spherical diameter” (e.s.d). The average particle size D50 is the e.s.d value of the particles measured in such a way that, in this way, 50% by volume of the particles have an equivalent spherical diameter less than this D50 value.

[0023] According to the present disclosure, the D 50 is about 5 to about 60 microns, such as about 15 to about 45 microns, or about 20 to about 40 microns, or about 25 to about 35 microns. In certain embodiments, the D 50 of the DE particles is about 35 microns.

[0024] In certain embodiments, the bulk density of the DE particles is about 0.05 g / cm 3 to about 0.20 g / cm 3 , such as about 0.06 g / cm 3 to about 0.19 g / cm 3 , such as about 0.07 g / cm 3 to about 0.18 g / cm 3 , such as about 0.08 g / cm 3 to about 0.17 g / cm 3 , such as about 0.09 g / cm 3from about 0.16 g / cm 3 from about 0.10 g / cm 3 from about 0.15 g / cm 3 from about 0.11 g / cm 3 from about 0.14 g / cm 3 from about 0.12 g / cm 3 from about 0.13 g / cm 3 .

[0025] The DE particles of the present disclosure can be calcined. Calcination refers to heating the DE particles in a kiln, such as a rotary kiln, to high temperatures, typically in excess of 1300°C. In certain embodiments, the DE particles are flux calcined. Flux calcined inorganic particles are processed and purified in a kiln in the same manner as calcined DE, but a natural flux is added to further increase agglomeration. Due to their higher permeability, they can be used to remove impurities at very high filtration flow rates. Calcined and flux calcined materials are well known and understood by those skilled in the art. Other inorganic particles described herein can also be calcined and flux calcined.

[0026] The DE particles can be a commercially available diatomite product. For example, at least one natural diatomite particle is a Standard Super Cel®, Hyflo Super Cel®, or Diactiv 11® material, available from Imerys Performance Materials.

[0027] The perlite typically comprises the following components: silicon dioxide, aluminum oxide, sodium oxide, potassium oxide, iron oxide, magnesium oxide, calcium oxide, water, and small amounts of other metallic elements.

[0028] The perlite particles of the present disclosure can be in the form of expanded perlite. Typically, expanded perlite includes one or more cells, or portions of cells, where a cell is a void space partially or completely surrounded by a glass wall, typically formed by the expansion of a gas while the glass is in a softened state. Methods of expanding perlite can include heating the perlite in air to a temperature of at least about 700°C, typically a temperature of 800°C to 1100°C, in an expansion furnace. An exemplary method of producing expanded perlite is described in US 2006 / 0075930, the entirety of which is incorporated herein by reference. The bulk volume of expanded perlite is typically up to 20 times the bulk volume of the unexpanded material.

[0029] The perlite can also be ground after expansion in the expansion furnace.

[0030] According to the present disclosure, the ground expanded perlite particles have a D50 of about 10 microns to about 60 microns, such as about 15 microns to about 45 microns, or about 20 microns to about 40 microns, or about 25 microns to about 35 microns. In certain embodiments, the ground expanded perlite particles have a D50 of about 15 microns.

[0031] In particular, the ground expanded perlite particles have a bulk density of about 0.05 g / cm3to about 0.20 g / cm3, such as about 0.06 g / cm3to about 0.19 g / cm3, or about 0.07 g / cm3to about 0.18 g / cm3, or about 0.08 g / cm3to about 0.17 g / cm3, or about 0.09 g / cm3to about 0.16 g / cm3, or about 0.10 g / cm3to about 0.15 g / cm3, or about 0.11 g / cm3to about 0.14 g / cm3, or about 0.12 g / cm3to about 0.13 g / cm3. 3 3 In particular, the ground expanded perlite particles have a bulk density of about 0.05 g / cm3to about 0.20 g / cm3, such as about 0.06 g / cm3to about 0.19 g / cm3, or about 0.07 g / cm3to about 0.18 g / cm3, or about 0.08 g / cm3to about 0.17 g / cm3, or about 0.09 g / cm3to about 0.16 g / cm3, or about 0.10 g / cm3to about 0.15 g / cm3, or about 0.11 g / cm3to about 0.14 g / cm3, or about 0.12 g / cm3to about 0.13 g / cm3. 3 3 In particular, the ground expanded perlite particles have a bulk density of about 0.05 g / cm3to about 0.20 g / cm3, such as about 0.06 g / cm3to about 0.19 g / cm3, or about 0.07 g / cm3to about 0.18 g / cm3, or about 0.08 g / cm3to about 0.17 g / cm3, or about 0.09 g / cm3to about 0.16 g / cm3, or about 0.10 g / cm3to about 0.15 g / cm3, or about 0.11 g / cm3to about 0.14 g / cm3, or about 0.12 g / cm3to about 0.13 g / cm3. 3 3 In particular, the ground expanded perlite particles have a bulk density of about 0.05 g / cm3to about 0.20 g / cm3, such as about 0.06 g / cm3to about 0.19 g / cm3, or about 0.07 g / cm3to about 0.18 g / cm3, or about 0.08 g / cm3to about 0.17 g / cm3, or about 0.09 g / cm3to about 0.16 g / cm3, or about 0.10 g / cm3to about 0.15 g / cm3, or about 0.11 g / cm3to about 0.14 g / cm3, or about 0.12 g / cm3to about 0.13 g / cm3. 3 3 In particular, the ground expanded perlite particles have a bulk density of about 0.05 g / cm3to about 0.20 g / cm3, such as about 0.06 g / cm3to about 0.19 g / cm3, or about 0.07 g / cm3to about 0.18 g / cm3, or about 0.08 g / cm3to about 0.17 g / cm3, or about 0.09 g / cm3to about 0.16 g / cm3, or about 0.10 g / cm3to about 0.15 g / cm3, or about 0.11 g / cm3to about 0.14 g / cm3, or about 0.12 g / cm3to about 0.13 g / cm3. 3 3 In particular, the ground expanded perlite particles have a bulk density of about 0.05 g / cm3to about 0.20 g / cm3, such as about 0.06 g / cm3to about 0.19 g / cm3, or about 0.07 g / cm3to about 0.18 g / cm3, or about 0.08 g / cm3to about 0.17 g / cm3, or about 0.09 g / cm3to about 0.16 g / cm3, or about 0.10 g / cm3to about 0.15 g / cm3, or about 0.11 g / cm3to about 0.14 g / cm3, or about 0.12 g / cm3to about 0.13 g / cm3. 3 3 In particular, the ground expanded perlite particles have a bulk density of about 0.05 g / cm3to about 0.20 g / cm3, such as about 0.06 g / cm3to about 0.19 g / cm3, or about 0.07 g / cm3to about 0.18 g / cm3, or about 0.08 g / cm3to about 0.17 g / cm3, or about 0.09 g / cm3to about 0.16 g / cm3, or about 0.10 g / cm3to about 0.15 g / cm3, or about 0.11 g / cm3to about 0.14 g / cm3, or about 0.12 g / cm3to about 0.13 g / cm3. 3 3 In particular, the ground expanded perlite particles have a bulk density of about 0.05 g / cm3to about 0.20 g / cm3, such as about 0.06 g / cm3to about 0.19 g / cm3, or about 0.07 g / cm3to about 0.18 g / cm3, or about 0.08 g / cm3to about 0.17 g / cm3, or about 0.09 g / cm3to about 0.16 g / cm3, or about 0.10 g / cm3to about 0.15 g / cm3, or about 0.11 g / cm3to about 0.14 g / cm3, or about 0.12 g / cm3to about 0.13 g / cm3. 3 3 .

[0032] In particular, the perlite product is obtained from a commercially available perlite product. In another embodiment, the at least one perlite product is a Harborlite® material available from Imerys Performance Materials; or a Europerl® available from Europerl GmbH.

[0033] Kaolinite is a clay mineral derived from kaolin with the chemical composition Al2Si2O5(OH)4. It is a layered silicate mineral in which a sheet of silicon-oxygen (SiO4) tetrahedral layers is linked to a sheet of octahedral layers of aluminum-oxygen (AlO6) octahedra through oxygen atoms.

[0034] ​​​​​​​​Rocks rich in kaolinite and halloysite are called kaolin. Kaolin, or its common name "china clay," is a hydrous aluminum silicate mineral that forms over millions of years through the hydrothermal decomposition of granite rocks. Hydrated kaolin is characterized by its fine particle size, platy or tabular particle shape, and chemical inertness. Calcined kaolin is an anhydrous aluminum silicate produced by heating ultrafine natural kaolin to high temperatures in a kiln. The calcination process increases whiteness and hardness and changes the size and shape of the kaolin particles. The kaolin of the present disclosure can have a D50 in the range of about 0.2 microns to about 5 microns.

[0035] Bentonite is a very soft, plastic clay composed primarily of montmorillonite, a fine-grained hydrous aluminum silicate and a member of the smectite group. Most bentonite is formed by the alteration in the presence of water of volcanic ash and tuff. The D50 of the bentonite used in the present disclosure can be 2 pm to 50 pm.

[0036] Sand is a granular material composed of finely divided mineral particles. Sand has various compositions, but is defined by its particle size. Sand is smaller than gravel and coarser than silt. Sand can also refer to a soil texture class or soil type, i.e., a soil containing more than 85% by mass of particles of sand size. The composition of sand varies according to local rock sources and conditions, but in inland continental and non-tropical coastal environments, the most common sand component is silica (silicon dioxide, or Si02), often in the form of quartz. Sand is often used to filter particles from a solution being filtered. The D50 of the sand particles used in the present disclosure can be 50 pm to 900 pm.

[0037] Silicoaluminophosphate molecular sieves (also known as SAPO's) are inorganic particles composed of PO2 + , AlO2 - , and SiO2tetrahedral units arranged in a three-dimensional microporous molecular sieve. These inorganic particles are composed primarily of silicon, aluminum, and phosphorous. SAPO's are a special class of zeolites that play an important role in ion exchange and separation processes due to their acidity and shape-selective properties. The D50 of the SAPO's used in the present disclosure can be 0.5 pm to 10 pm.

[0038] The above-described silicon-containing particles are well known to those skilled in the art. Thus, those skilled in the art are aware of various types of filter aid inorganic particles and can select the type and size appropriate for the selected filtration method. For all of the inorganic particles described herein, the D100 of each material is no greater than 1000 pm.

[0039] Filter aid According to the present invention, there is provided a filter aid, wherein the filter aid comprises: a first composition comprising inorganic particles comprising silicon; and a second composition comprising a dicarboxylic acid or a polymer of a dicarboxylic acid.

[0040] In some embodiments, the filter aid comprises a mixture of the first composition and the second composition. In some embodiments, the filter aid comprises a dry mixture or a wet mixture of the first composition and the second composition. In some embodiments, the first composition and the second composition are separate (e.g., not mixed). In some embodiments, the first composition is a substrate and the second composition is a coating on the substrate.

[0041] In some embodiments, a filter aid is provided, wherein the filter aid comprises: inorganic particles comprising silicon; a coating selected from: a) an organic coating, wherein the organic coating comprises (i) a dicarboxylic acid; or (ii) a polymer or copolymer of a dicarboxylic acid; b) an inorganic polymeric coating, wherein the inorganic polymeric coating comprises a halogenated metal polymer; and c) a combination of (a) and (b).

[0042] In some embodiments, a filter aid is provided comprising inorganic particles comprising silicon and an organic coating, wherein the organic coating comprises (i) a dicarboxylic acid; or (ii) a polymer of a dicarboxylic acid.

[0043] In some embodiments, a filter aid is provided comprising inorganic particles comprising silicon and an inorganic polymeric coating, wherein the inorganic polymeric coating comprises a halogenated metal polymer.

[0044] In certain embodiments, the filter aid consists of inorganic particles comprising silicon and a polymeric coating as described herein.

[0045] The filter aid of the present disclosure has a measured permeability of greater than 300 millidarcy, such as from greater than 300 millidarcy to 1500 millidarcy.

[0046] Permeability is a measure of the rate at which liquid flows through a porous medium or particulate filter cake. The method for measuring permeability is described below and is incorporated herein by reference: Tiller, FM and W. Li, Theory and Practice of Solid / Liquid Separation, 4th Edition, 2002, University of Houston, Tiller, FM, Tutorial: Interpretation of Filtration Data, I, Fluid / Particle Separation Journal, Vol.3, 85-94, 1990. This measurement technique is well known to those skilled in the art.

[0047] The filter aid composition can be formed into sheets, pads, cartridges or other products for performing filtration functions.

[0048] The filter aid disclosed herein can be used in a variety of processes and compositions, as well as in a variety of filtration methods. In some embodiments, the filter aid material is applied to a filter diaphragm to protect it and / or improve the clarity of the liquid to be filtered during the filtration process.

[0049] The filter aid material disclosed herein can also be used in a variety of filtration methods. Filtration methods may include pre-coating at least one filter element with the composition of this disclosure, and contacting at least one liquid to be filtered with at least one coated filter element. In such embodiments, the contact may include passing the liquid through the filter aid material or a filter element containing the filter aid material. The filtration method may further include suspending the filter aid material in at least one liquid containing particles to be removed from the liquid, and then separating the filter aid material from the filtrate.

[0050] Filter aid materials containing the compositions disclosed herein can also be used to filter various types of liquids. Those skilled in the art will readily recognize those liquids that can be filtered.

[0051] In some embodiments, the liquid is a beverage. Exemplary beverages include, but are not limited to, vegetable-based juices, fruit juices, distilled spirits, and malt-based liquids. Exemplary malt-based liquids include, but are not limited to, beer and wine. In some embodiments, the liquid is a liquid that readily forms a haze upon cooling. In some embodiments, the liquid is a beverage that readily forms a haze upon cooling. In some embodiments, the liquid is beer. In some embodiments, the liquid is a hydrocarbon, including oils. In some embodiments, the liquid is edible oil. In some embodiments, the liquid is fuel oil, such as biofuels. In some embodiments, the liquid is water, including, but not limited to, wastewater. In some embodiments, the liquid is blood. In some embodiments, the liquid is sake. In some embodiments, the liquid is a sweetener, such as, for example, corn syrup or molasses.

[0052] In some embodiments, the filter aid of this disclosure is used for extracting unwanted particles from metal-containing solutions, such as metal-containing brine, and for filtration methods to remove unwanted particles from brine. The metal may be an alkaline earth metal, such as lithium. The unwanted particles may be salts, such as calcium carbonate and magnesium carbonate.

[0053] Polymer In some embodiments of this disclosure, the filter aid comprises a substrate including a coating. The coating may partially or completely coat the inorganic particles described herein. In some embodiments, the filter aid comprises a second composition comprising a dicarboxylic acid or a dicarboxylic acid polymer.

[0054] The organic coating contains (i) dicarboxylic acid; or (ii) a dicarboxylic acid polymer.

[0055] The term "dicarboxylic acid" is used to describe organic compounds containing two carbonyl groups. Its formula is HO₂C-R-CO₂H, where R can be aliphatic (saturated or unsaturated) or aromatic. Suitable examples of dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, 1,4-cyclohexanedicarboxylic acid, azelaic acid, decanedioic acid, undecanedoic acid, and dodecanedoic acid.

[0056] Specifically, the dicarboxylic acid may be selected from itaconic acid, malonic acid, maleic acid, succinic acid, glutaric acid or adipic acid, or a salt thereof.

[0057] The dicarboxylic acid polymer may also comprise a copolymer. The copolymer may comprise at least one of the following: sulfonate groups (SO3) - ·X + );or phosphate groups (PO3H) - ·X + );or Phosphonate group (PO3) -2 ·X + );or hydroxyl (OH), or ester bond, X includes NH4, Li, H, Na, Ca, K, or Mg.

[0058] In some embodiments, the ester bond may be contained in a polymer of acetate, acrylate, or a combination thereof.

[0059] In particular, the organic coating or the second composition contains an itaconic acid monomer, or is a polymer such as polyitaconic acid, or a salt thereof (formed as shown in the figure below).

[0060]

[0061] Specifically, the organic coating or second composition may comprise a copolymer containing itaconic acid and a sulfonic acid. Specifically, the sulfonic acid may be selected from styrene sulfonic acid and 2-acrylamido-2-methylpropanesulfonic acid, or salts thereof (see the formation diagram below, respectively).

[0062]

[0063] In some embodiments, the organic coating or second composition comprises a polyitancica copolymer, such as those commercially available from Itaconix®. Examples of polyitancica copolymers that can be used in this disclosure include, but are not limited to: • Itaconix® CHT TM 121 (poly(itaconic acid-copoly-styrene sulfonate sodium salt) - referred to herein as Itaconix 121; • Itaconix® CHT TM 122 (poly(itaconic acid-copolymer-2-acrylamido-2-methyl-1-propanesulfonate sodium salt) - referred to herein as Itaconix 122; • Itaconix® DSP 2K G (Sodium Polyitacrylate) - referred to as Itaconix DSP 2K G in this document; • Itaconix TSI 322 G (poly(itaconic acid-copolymer-2-acrylamido-2-methyl-1-propanesulfonate sodium salt) - referred to herein as Itaconix 322 G; Advantageously, the Itaconix® family is bio-based and environmentally safe.

[0064] The organic coating or second composition may be in the form of a powder or an aqueous solution.

[0065] In some embodiments, the polymer coating is an inorganic polymer coating comprising a metal halide polymer. The metal halide polymer has the following formula: Al n (OH) m Cl (3n-m) Where n is 2 to 20 and m is 4 to 20; or Fe n (OH) m Cl (3n-m) , where n is 2 to 20 and m is 4 to 20.

[0066] The inorganic polymer may include polyaluminum chloride, polyiron chloride, and mixtures thereof. Polyiron chloride is also known as polyferric chloride.

[0067] In some embodiments, the first composition comprises inorganic particles comprising DE (which may be calcined or flux-calcined) or perlite (which may be expanded perlite and may be milled), or is composed of DE or perlite. In some embodiments, the filter aid comprises a mixture of the first and second compositions. In some embodiments, the filter aid comprises a dry mixture of the first and second compositions. In some embodiments, the filter aid comprises a wet mixture of the first and second compositions. In some embodiments, the first composition is a substrate, and the second composition is a coating on the first composition. In some embodiments, the inorganic particles are coated with an organic polymer comprising a polyitacrylic acid copolymer.

[0068] In some embodiments, the inorganic particles comprise DE (which may be calcined or flux-calcined) or perlite (which may be expanded perlite), or are composed of DE or perlite, and the inorganic particles are coated with an inorganic polymer comprising polyaluminum chloride or polyferric chloride.

[0069] The inventors have unexpectedly discovered that the filter aid disclosed herein advantageously reduces the silicon solubility of inorganic particles when exposed to aqueous solutions. The filter aid comprises a first composition containing inorganic particles and a second composition containing dicarboxylic acids or dicarboxylic acid polymers, the inorganic particles containing silicon. For example, when silicon-containing inorganic particles are present in aqueous solutions, such as salt solutions in a specific pH range of 2 to 12, the inorganic particles may leach silicon.

[0070] Furthermore, the inventors have unexpectedly discovered that the organic and inorganic coatings according to this disclosure have a mitigating effect on silicon dissolution from silicon-containing inorganic particles.

[0071] Without being bound by theory, the inventors have discovered that the coating or polymer of the filter aid prepared according to this disclosure can also chelate with unwanted particles (impurities present in the liquid to be filtered). The inorganic particles themselves can further absorb other unwanted particles.

[0072] A method of making a filter aid comprises: In some embodiments of this disclosure, a method for preparing a filter aid is provided, comprising: A first composition comprising inorganic particles is mixed with a second composition comprising dicarboxylic acid or a dicarboxylic acid polymer, wherein the inorganic particles comprise silicon.

[0073] The first and second compositions may or may not be mixed with water. Mixing the first and second compositions without water produces a "dry mixture," while mixing the first and second compositions with water produces a "wet mixture."

[0074] In some embodiments, a method for preparing a filter aid is provided, comprising: coating inorganic particles with a coating, wherein the inorganic particles comprise silicon; and wherein the coating is selected from: a) An organic coating, wherein the organic coating comprises (i) a dicarboxylic acid; or (ii) a dicarboxylic acid polymer; b) An inorganic polymer coating, wherein the inorganic polymer coating comprises a metal halide polymer; and c) The combination of (a) and (b).

[0075] To coat inorganic particles with a coating, either a wet-addition coating process or a dry-addition coating process can be used. In a dry-addition process, the inorganic particles and the dry components of the coating are added together, water is added, and the components are mixed.

[0076] After the coating step, the coated product is dried in an oven at a temperature of 70°C to 100°C.

[0077] The dried product is then dispersed and sieved to restore the particle size distribution of the resulting filter aid.

[0078] In the examples prepared according to this disclosure and described below, dry DE or dry perlite was combined with dry Itaconix® product. Deionized water was then added to the dry mixture (at a ratio of 0.5:1 or 1:1), and the wet mixture was now thoroughly mixed to allow the polymer coating to bond with and coat the inorganic particles. The sample was then dried in an oven at 90°C for several hours.

[0079] In the wet-addition coating process, the selected dry inorganic particles are blended with a polymer coating solution already prepared in a container. The same method as described above for dry mixtures is followed, except that Itaconix® products are supplied as a solution, thus eliminating the need for a water addition step.

[0080] A method of filtering a liquid According to this disclosure, a method is provided comprising contacting a first composition and a second composition described herein with a desired liquid to be filtered (as described above) to filter unwanted particles from the liquid, forming a filtrate. In some embodiments, the first composition and the second composition may be added to the liquid in such a manner as i) simultaneously added to the liquid in the form of a filter aid as prepared and described herein (as a dry mixture or as a wet mixture or as a coated substrate in which the first composition is the substrate and the second composition is a coating on the substrate), or ii) simultaneously and / or sequentially added to the liquid in any order of addition. Unwanted particles may be fine particles or impurities. Unwanted particles may include, but are not limited to, salts, metals, oils, and fatty acid esters. The filter aid or the first composition itself may also be used as an absorbent to absorb unwanted particles.

[0081] In some embodiments, the pH of the liquid is 12 or lower, or 11.5 or lower, or 11 or lower, or 10 or lower, or 2 to about 12, or 2 to about 11.5, or 2 to about 11, or 2 to about 10, or 9.8 or lower, or 9.7 or lower, or 9.5 or lower; and the contact is performed at a temperature of 50°C to 100°C, or at least 50°C, or at least 60°C, or at least 65°C, or at least 70°C.

[0082] A method of preventing or reducing the leaching of silicon from a filter aid into an aqueous solution during a filtration process In some embodiments of this disclosure, a method is provided to prevent or reduce the leaching of silicon from a filter aid into a liquid during filtration, the method comprising: The first composition is mixed with the second composition to form a filter aid, and the liquid is filtered with the filter aid to form a filtrate. The first composition comprises inorganic particles, the inorganic particles comprising silicon, and The second composition comprises a dicarboxylic acid or a dicarboxylic acid polymer.

[0083] In some embodiments of this disclosure, a method is provided to prevent or reduce the leaching of silicon from a filter aid into a liquid during filtration, the method comprising: The first and second compositions as described herein are brought into contact with the liquid to be filtered in order to filter unwanted particles from the liquid to form a filtrate. In some embodiments, the first and second compositions may be added to the liquid in such a manner as i) simultaneously added to the liquid as a filter aid as prepared and described herein (as a dry mixture, as a wet mixture, or as a coated substrate in which the first composition is the substrate and the second composition is a coating on the substrate), or ii) simultaneously and / or sequentially added to the liquid in any order of addition. Unwanted particles may be fine particles or impurities. Unwanted particles may include, but are not limited to, salts, metals, oils, and fatty acid esters. The filter aid or the first composition itself may also be used as an absorbent to absorb unwanted particles.

[0084] In some embodiments, a method is provided that includes coating inorganic particles with a coating to form a filter aid, and filtering a liquid with the filter aid to form a filtrate. The inorganic particles comprise silicon; and the coating is selected from: a) An organic coating, wherein the organic coating comprises (i) a dicarboxylic acid; or (ii) a dicarboxylic acid polymer; b) An inorganic polymer coating, wherein the inorganic polymer coating comprises a metal halide polymer; and c) The combination of (a) and (b).

[0085] In some embodiments, the liquid is an aqueous solution. In other embodiments, the liquid is an oil. Those skilled in the art will readily recognize that liquids desirably filtered using methods including filter aids may include, but are not limited to, beverages, oils, fuel oils such as biofuels, water, or blood.

[0086] In some embodiments, the aqueous solution is a metal-containing solution, such as an alkaline earth metal salt solution.

[0087] Traditional metal mining practices utilize ancient volcanic systems whose magmatic activity has long since ceased, and whose brine has deposited its metal load as solid ore. These ore bodies can be mined in giant open-pit or underground pits. An alternative approach involves extracting brine directly from hot igneous rocks, such as those beneath dormant volcanic systems or above young granite intrusions. So-called "brine mining" extracts metals from concentrated solutions rather than solid rock.

[0088] Typical hydrometallurgical and chemical processes are used to extract metals from rocks or brine. Salts such as magnesium carbonate and calcium carbonate are often used for precipitation and ion-exchange reactions to promote the crystallization of the metal in the desired form. An example of this is lithium mining, where magnesium carbonate and calcium carbonate salts are added to lithium brine to precipitate the desired salt, but are subsequently removed by filtration using a filter aid.

[0089] In some embodiments, the filter aid according to this disclosure is used in such metal extraction methods to filter out unwanted particles, such as the salts described above. After filtration using the filter aid of this disclosure, the resulting alkaline earth metal brine was found to have a silicon concentration of less than 10 ppm, for example, less than 5 ppm.

[0090] In some implementations, the alkaline earth metal brine is a lithium brine.

[0091] It should be understood that this disclosure is not limited to the above-described embodiments, and various modifications and improvements can be made without departing from the concepts described herein. Except where mutually exclusive, any feature may be used separately or in combination with any other feature, and this disclosure extends to and includes all combinations and sub-combinations of one or more features described herein.

[0092] Example The following examples describe the preparation of filter aids comprising inorganic particles coated with various coatings, or the preparation of filter aids comprising a first composition of inorganic particles and a second composition comprising dicarboxylic acid or a dicarboxylic acid polymer. Various combinations of inorganic particles and polymer coatings, as well as the first and second compositions, are prepared and tested according to the procedures described below.

[0093] Filter aid preparation method 1: 100g of each of the dry inorganic particles in Table 1 (inorganic particle materials 1-4) was blended with the dry polymers in Table 2 in the dry state. In the examples below, the polymer (coating) is described as being present in an amount of 0.5% to 3% by weight (wt%). This indicates that the coating is present in an amount of 0.5g to 3g of coating per 100g of inorganic particles.

[0094] Deionized water was added to the dry blend at a ratio of 0.5:1 and mixed. The sample was dried in an oven at 90°C for 3 hours and then sieved through a 60M sieve. The resulting coated filter aid product (“Coated Product”) is listed in Table 5.

[0095] Filter aid preparation method 2: 100g of each type of dry inorganic granules (inorganic granule materials 1-4) from Table 1 was blended with each type of polymer (0.5g to 3g per 100g of inorganic granules) prepared in aqueous solution from Table 2. The samples were then dried in an oven at 90°C for 3 hours and sieved through a 60M sieve. The resulting products are listed in Table 5.

[0096] Filter aid preparation method 3: Blend 100g of each of the dry inorganic particles in Table 1 (inorganic particle materials 1-4) with each of the polymers in Table 2 (Itaconix materials) (0.5 to 3g per 100g of inorganic particles). Prepare the blend as a dry blend or a wet blend. For both dry and wet blends, mechanically blend the sample in a suitable blending container (e.g., a plastic container or kitchen blender) for 15 minutes. The resulting filter aid products (“dry or wet products”) are listed in Table 6.

[0097] Filter aid preparation method 4: Separately measure the dry inorganic particles (inorganic particle materials 1-4) in Table 1 and the various polymers (Itaconix materials) in Table 2, totaling 100g of powder. As described below, the inorganic particles and Itaconix materials are not blended and are added simultaneously or sequentially.

[0098] Table 1: Inorganic Particulate Materials

[0099] Table 2: Chemical properties of the polymer of the present invention and comparative polymers

[0100] NaCl medium 3g of each of the above-described filter aid products was stirred in 100mL of 1M NaCl (medium 5, as described in Table 3) at 65°C for 1 hour, and then filtered using a disposable 0.45μm Fisher brand plastic filter. The filtrate was diluted 50:1 with high-purity water, acidified, and the soluble Si was analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES). 3g of products A, F, and GG were each tested as described above at different pH values. The results of these tests are shown in Tables 4 and 7 below. Furthermore, 3g of products A, GG, HH, JJ, and KK were each tested as described above in medium 5 but at a neutral pH, and also in medium 5 but at pH 9.8. The results of these tests are shown in Tables 8 and 9 below.

[0101] For product HH, the inorganic particulate material and Itaconix material are not blended, are measured separately, and are added to medium 5 simultaneously.

[0102] For product JJ, the inorganic particulate material and Itaconix material were measured separately and not blended. First, the inorganic particulate material was added to medium 5 and stirred for one minute, then the Itaconix material was added to medium 5.

[0103] For product KK, the inorganic particulate material and Itaconix material were measured separately and not blended. First, the Itaconix material was added to medium 5 and stirred for one minute, then the inorganic particulate material was added to medium 5.

[0104] For product LL, the inorganic particulate material was mechanically blended with a copolymer solution of acrylic acid and itaconic acid to form a wet mixture. Product LL was added to medium 5 and the above tests were performed. The results of these tests are shown in Table 10 below.

[0105] Lithium brine substitute (surrogate) / potassium hydrogen phthalate medium 3 g of each of the above-described filter aid products was stirred in 100 mL of Li-based saline substitute salts (mediums 1-4 and 7, as described in Table 3) at 65°C for 1 hour, and then filtered using a disposable 0.45-micron Fisher brand plastic filter. The filtrate was diluted 50:1 with high-purity water, acidified, and the soluble Si was analyzed by ICP-OES. 5 g of each of the above-described products was stirred in 200 mL of 1% potassium hydrogen phthalate (medium 6 as described in Table 3) at room temperature for 2 hours. The extract was filtered using a disposable 0.45-micron Fisher brand plastic filter. The soluble Si of the filtrate was analyzed by ICP-OES. The results of these tests are shown in Table 11 below.

[0106] Table 3

[0107] Variable = pH value given in Table 4 "Silicon solubility in 1M NaCl at different pH values" Table 4: Silicon solubility in medium 5 (1M NaCl) at different pH values

[0108] Table 5: List of Coated Products

[0109] Table 6: List of dry and wet products (blended or added separately)

[0110] Table 7: Silicon solubility in medium 5 (2M NaCl) at different pH values

[0111] Table 8: Silicon solubility in medium 5 (2M NaCl) at neutral pH

[0112] Table 9: Silicon solubility in medium 5 (2M NaCl) at pH 9.8

[0113] Table 10: Silicon solubility in medium 5 (2M NaCl) at neutral pH

[0114] Table 11: Results for media 1 to 4, 6, and 7. Solid bars indicate that the products below are comparative examples.

[0115]

[0116]

[0117]

[0118] The results in Table 11 show that the filter aid prepared according to this disclosure exhibits a significantly lower percentage of soluble silica compared to comparative examples (e.g., products A, S, U, and X).

Claims

1. A filter aid, the filter aid comprising: a first composition comprising inorganic particles, the inorganic particles comprising silicon; and a second composition comprising a dicarboxylic acid or a dicarboxylic acid polymer.

2. The filter aid of claim 1, wherein the dicarboxylic acid is selected from itaconic acid, malonic acid, maleic acid, succinic acid, glutaric acid, or adipic acid.

3. The filter aid of claim 1 or 2, wherein the dicarboxylic acid polymer comprises a copolymer.

4. The filter aid of claim 3, wherein the copolymer comprises at least one of: sulfonate groups (SO3 - • X + ); or phosphate group (PO3H - • X + ); or phosphonate groups (PO3 -2 • X + ); or a hydroxyl (OH); or an ester linkage, wherein X comprises NH4, Li, H, Na, Ca, K, or Mg.

5. The filter aid of any one of claims 1 to 4, wherein the second composition comprises itaconic acid, an itaconic acid polymer, or an itaconic acid copolymer.

6. The filter aid of any one of claims 1 to 5, wherein the second composition comprises a copolymer comprising itaconic acid and a sulfonic acid.

7. The filter aid of claim 6, wherein the sulfonic acid is selected from 2-acrylamido-2-methylpropane sulfonic acid and styrene sulfonic acid.

8. The filter aid of any one of claims 1 to 7, wherein the inorganic particles comprise diatomite, perlite, expanded perlite, expanded ground perlite, sand, bentonite, silica gel, kaolinite, zeolite, silicoaluminophosphate molecular sieves, or a mixture thereof.

9. The filter aid of claim 8, wherein the inorganic particles are calcined diatomite or flux calcined diatomite.

10. The filter aid of any one of claims 1 to 9, wherein the filter aid comprises a mixture of the first composition and the second composition.

11. The filter aid of claim 10, wherein the mixture of the first composition and the second composition is a dry mixture.

12. The filter aid of claim 10, wherein the mixture of the first composition and the second composition is a wet mixture.

13. The filter aid of any one of claims 1 to 9, wherein the first composition is a substrate and the second composition is a coating on the first composition.

14. The filter aid of any one of claims 1 to 13, wherein the filter aid has a permeability greater than 300 millidarcies as measured in the specification.

15. Use of a filter aid for filtering a liquid, the use comprising: contacting the filter aid of any one of claims 1 to 14 with the liquid so as to filter unwanted particles from the liquid to form a filtrate.

16. The use of claim 15, wherein the first composition and the second composition of the filter aid are added to the liquid i) simultaneously in the form of a mixture of the first composition and the second composition, or ii) simultaneously and / or sequentially in any order of addition to the liquid.

17. The use of claim 15, wherein the first composition and the second composition are added to the liquid in the form of the filter aid comprising a dry or wet mixture of the first composition and the second composition.

18. The use of claim 15, wherein the filter aid is a coated substrate, wherein the first composition is a substrate and the second composition is a coating on the substrate.

19. The use of any one of claims 15-18, wherein the aqueous solution has a pH of 12 or less, or 11.5 or less, or 11 or less, or 10 or less, or from 2 to about 12, or from 2 to about 11.5, or from 2 to about 11, or from 2 to about 10, or 9.8 or less, or 9.7 or less, or 9.5 or less; and wherein the temperature of the liquid is from 50°C to 100°C, at least 50°C, at least 60°C, at least 65°C, or at least 70°C.

20. The use of any one of claims 15-19, wherein the liquid is a metal-containing brine, and the filtration process removes unwanted particles from the brine.

21. The use of claim 20, wherein the metal-containing brine is a lithium brine.

22. Use of a filter aid for preventing or reducing leaching of silicon into a liquid during filtration, the use comprising: mixing a first composition with a second composition to form the filter aid, and filtering the liquid with the filter aid to form a filtrate, wherein the first composition comprises inorganic particles comprising silicon, and wherein the second composition comprises a dicarboxylic acid or a dicarboxylic acid polymer.

23. The use of claim 22, wherein the filtrate has a silicon concentration of less than 10 ppm, for example less than 5 ppm.

24. Use of a first composition and a second composition for making a filter aid, the use comprising: mixing the first composition with the second composition, wherein the first composition comprises inorganic particles comprising silicon, and the second composition comprises a dicarboxylic acid or a dicarboxylic acid polymer.

25. A method of filtering a liquid, the method comprising: contacting a filter aid according to claims 1-14 with the liquid so as to filter unwanted particles from the liquid to form a filtrate.

26. The method of claim 25, wherein the first composition and the second composition of the filter aid are added to the liquid i) simultaneously in the form of a mixture of first and second compositions, or ii) simultaneously and / or sequentially in any order of addition to the liquid.

27. The method of claim 25, wherein the first composition and the second composition are added to the liquid in the form of the filter aid comprising a dry or wet mixture of first and second compositions.

28. The method of claim 25, wherein the filter aid is a coated substrate, wherein the first composition is a substrate and the second composition is a coating on the substrate.

29. The method of any one of claims 25-28, wherein the aqueous solution has a pH of 12 or less, or 11.5 or less, or 11 or less, or 10 or less, or from 2 to about 12, or from 2 to about 11.5, or from 2 to about 11, or from 2 to about 10, or 9.8 or less, or 9.7 or less, or 9.5 or less; and wherein the temperature of the liquid is from 50°C to 100°C, at least 50°C, at least 60°C, at least 65°C, or at least 70°C.

30. The method of any one of claims 25-29, wherein the liquid is a metal-containing brine, and the filtration method removes unwanted particulates from the brine.

31. The method of any one of claims 25-30, wherein the metal-containing brine is a lithium brine.

32. A method of preventing or reducing leaching of silicon from a filter aid into a liquid during filtration, the method comprising: mixing a first composition with a second composition to form a filter aid, and filtering the liquid with the filter aid to form a filtrate, wherein the first composition comprises inorganic particles comprising silicon, and wherein the second composition comprises a dicarboxylic acid or a dicarboxylic acid polymer.

33. The method of claim 32, wherein the filtrate has a silicon concentration of less than 10 ppm.

34. A method of making a filter aid, the method comprising: mixing a first composition comprising inorganic particles comprising silicon with a second composition, wherein the second composition comprises a dicarboxylic acid or a dicarboxylic acid polymer.

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