WO2019246082A1

WO2019246082A1 - Methods of preparation and utilization of bauxitic kaolins

Info

Publication number: WO2019246082A1
Application number: PCT/US2019/037710
Authority: WO
Inventors: Ismail Yildirim; Amy RAY; Sharad Mathur; Ashok Khokhani; James Godfrey; Randy MUMFORD
Original assignee: Basf Corporation
Priority date: 2018-06-18
Filing date: 2019-06-18
Publication date: 2019-12-26

Abstract

Bauxitic kaolins, compositions comprising the same, and methods of making and using the bauxitic kaolins are disclosed herein. The bauxitic kaolins can have an Al₂O₃ content of greater than 50% to 85% by weight (on a calcined basis), a loss on ignition of at least 17% by weight, and a surface area of at least 100 m²/g, as determined by a Micrometrics Gemini 2370 surface area analyzer. The bauxitic kaolins can be used in various applications depending on their average particle size and/or particle size distribution as well as other desired properties. In some embodiments, the bauxitic kaolin can be used as a flame retardant filler in applications such as carpets and plastics or as an adsorbent.

Description

METHODS OF PREPARATION AND UTILIZATION OF BAUXITIC KAOLINS

FIELD OF THE DISCLOSURE

This disclosure relates generally to bauxitic kaolins for use in, for example, carpet backings and plastics.

BACKGROUND OF THE DISCLOSURE

Bauxitic kaolins can be encountered in the upper, in between or at the bottom of kaolinite layers. However, bauxitic kaolins do not possess uniform chemical and physical characteristics, their appearance and composition vary from geographical location to geographical location and even within the same geographical location, and they can differ in properties from local mining site to mining site. This large variation in properties pose insurmountable problems and discouraged those skilled in the art from using bauxitic kaolin as a flame -retarding agent. A further problem is that grinding bauxitic kaolins for use in filler applications typically produces considerably more fines than grinding aluminum trihydroxide (ATH) and these excessive fines can cause viscosity and processing problems. Therefore, bauxitic kaolins are either discarded, left in the ground or sold as raw materials to other end users such as those making alumina-silicate refractory materials, ceramic proppants, and cements.

A need exists for methods for producing a usable bauxitic kaolin material from crude bauxitic deposits that can be used as a suitable flame -retarding agent. The materials and methods disclosed herein address these and other needs.

SUMMARY OF THE DISCLOSURE

Bauxitic kaolins, compositions comprising the same, and methods of making and using the bauxitic kaolins are disclosed herein. The bauxitic kaolins can have an AI2O3 (also referred to herein as mineral gibbsite, boehmite, alpha-alumina trihydrate and/or monoclinic hydrated alumina kaolin) content of greater than 50% to 85% by weight, a loss on ignition of at least 17% by weight, and a surface area of at least 100 m²/g, as determined by a Micrometries Gemini 2370 surface area analyzer. In some embodiments, the AI2O3 content of the bauxitic kaolin can be greater than 60% (such as greater than 60% to 85%) or greater than 70% (such as greater than 70% to 85%) by weight (on a calcined basis). In some embodiments, the loss on ignition of the bauxitic kaolin can be from 17% to 30% by weight. The bauxitic kaolin can have a GE Brightness of at least 55.

The bauxitic kaolins disclosed herein can include a surface modifying agent. In some instances, the surface modifying agent comprises a dispersant. The surface modifying agent can further comprise a pH modifier. In specific embodiments, the surface modifying agent comprises an organic dispersant and an alkaline-based pH modifier. The organic dispersant can be a polyacrylate polymer and can be present in an amount of from 0.05% to 3%, such as from 0.5% to 1.5% by weight of the bauxitic kaolin. The alkaline-hased pH modifier can comprise caustic soda and can be present in an amount such that an aqueous dispersion containing 78 grams or greater of the bauxitic kaolin/22 grams of water

(equivalent to 78% or greater solids concentration in water) has a pH of at least 9.0 when measured at 20°C. When the organic dispersant and the alkaline-based pH modifier are present in the bauxitic kaolins, they can be in a weight ratio of from 1:10 to 1:1, such as from 1:5 to 1:1.

The presence of the surface modifying agent can improve the stability of dispersions comprising the bauxitic kaolin. Similarly, the particle size distribution of the bauxitic kaolin can contribute to the stability of dispersions comprising the bauxitic kaolin. The stability of the dispersions can be demonstrated by their viscosities. For example, aqueous dispersions comprising the bauxitic kaolin and optionally, the surface modifying agent can have a Brookfield viscosity of from 1000 cps to 2500 cps (78% solids or higher), as determined using a #2 spindle at 20 rpm and 20°C.

The bauxitic kaolins can be used in various applications depending on their average particle size and/or particle size distribution. In some embodiments, the bauxitic kaolin comprises particles having a coarse particle size. The coarse particle size bauxitic kaolin can have nominal (maximum) particle size diameter of 250 microns or less, as measured by a Microtrac Model S3500 Particle Size Analyzer. In these embodiments, the particle size distribution as measured by a Microtrac Model S3500 Particle Size Analyzer, of the bauxitic kaolin can comprise at least 55%, such as at least 60% or at least 65% of the particles by weight having a diameter of 44 microns or greater.

In certain embodiments, the coarse particle size bauxitic kaolin can comprise 2% or greater of the particles by weight having a diameter of 149 microns or greater; 8% or greater of the particles by weight having a diameter of 88 microns or greater; and 10% or greater of the particles by weight having a diameter of 74 microns or greater. For example, the coarse particle size bauxitic kaolin can comprise 2% or greater of the particles by weight having a diameter of 149 microns or greater; 20% or greater of the particles by weight having a diameter of 88 microns or greater; and 30% or greater of the particles by weight having a diameter of 74 microns or greater. In specific embodiments, the coarse particle size bauxitic kaolin can comprise 2% or greater of the particles by weight having a diameter of 149 microns or greater; 25% or greater of the particles by weight having a diameter of 88 microns or greater; 40% or greater of the particles by weight having a diameter of 74 microns or greater; and 60% or greater of the particles by weight having a diameter of 44 microns or greater.

The coarse bauxitic kaolin can have a median particle diameter (dso) of from 25 to 75 pm, such as 50 pm or greater, as measured on a Microtrac Model S5300 Particle Size Analyzer. The average surface area of the coarse bauxitic kaolin can be at least 200 m²/g, as determined by a Micrometries Gemini 2370 particle size analyzer.

Compositions comprising the coarse bauxitic kaolin are also disclosed herein. The compositions can include the coarse bauxitic kaolin and a latex. The latex can include, for example, a styrene butadiene latex. The Brookfield viscosity of compositions comprising the coarse bauxitic kaolin can be 1000 cps or less, as determined using a #3 spindle at 20 rpm and 20°C. In some embodiments, the compositions can have a limiting oxygen index of at least 27, as determined by ASTM D2863-13. The compositions comprising the coarse bauxitic kaolin can be used in various articles. In some embodiments, the coarse bauxitic kaolin compositions can be used as a flame retardant filler in carpet backing. In specific embodiments, the article does not include additional alumina trihydrate other than provided by the bauxitic kaolin.

As disclosed herein, the bauxitic kaolins can be used in various applications depending on their average particle size and/or particle size distribution. In some embodiments, the bauxitic kaolin comprises particles having a fine particle size. The fine particle size bauxitic kaolins can have a nominal particle size diameter of 10 microns or less, as determined by a Sedigraph 5100 Particle Analyzer, and a +325 mesh residue content of 20 ppm or less. In other embodiments, the fine particle size bauxitic kaolin can have nominal (maximum) particle size diameter of 25 microns or less (such as 20 microns or less, 15 microns or less, or 10 microns or less), as measured by a Microtrac Model S3500 Particle Size Analyzer, and an average surface area of at least 170 m²/g. The particle size distribution as measured by a Microtrac Model S3500 Particle Size Analyzer, of the fine particle size bauxitic kaolin can comprise at least 92% of the particles by weight having a diameter of less than 5 microns; at least 65% of the particles by weight having a diameter of less than 2 microns; at least 45% of the particles by weight having a diameter of less than 1 micron; and at least 27% of the particles by weight having a diameter of less than 0.5 micron. The fine particle size bauxitic kaolin can have a median particle diameter (d₅o) of 2 microns or less, such as from 1 to 2 microns, as determined by a Sedigraph 5100 Particle Analyzer.

Compositions comprising the fine particle size bauxitic kaolin are also disclosed.

The compositions can include the fine particle size bauxitic kaolin and a polymer. The polymer can be selected from polyesters, polyamides, rubbers, polyacrylics, epoxy polymers, polyurethanes, ethylene and propylene copolymers, polyvinyl chlorides, polyolefins, polystyrenes, or a mixture thereof. The compositions comprising the fine particle size bauxitic kaolin can be used in various articles. In some embodiments, the fine particle size bauxitic kaolin compositions can be used as a flame retardant filler in plastic materials.

The bauxitic kaolin can also be used as adsorbents. The adsorbents can comprise meta-bauxitic kaolin (bauxitic kaolin calcined at 450°C or greater) having a surface area of at least 100 m²/g, as determined by a Micrometries Gemini 2370 surface area analyzer and a particle size range from a few millimeters to micron particle size depending on the application. In some embodiments, the meta-bauxitic kaolin particle size can be 8x14 mesh or less, such as 2.5 mm or less, or from 85 pm to 2.5 mm. In some embodiments, the meta- bauxitic kaolin can have a d90 particle size of 95 pm or less or from 85 pm to 95 pm, as determined by a Microtrac Model S3500 Particle Size Analyzer. In some embodiments, the surface area of the meta-bauxitic kaolin can be from 100 m²/g to 200 m²/g or from 170 m²/g to 200 m²/g.

Methods of processing a crude bauxitic kaolin to produce a refined bauxitic kaolin are also disclosed. In some instances, the crude kaolin can have an AI2O3 content greater than 50% or greater than 60% by weight (on a calcined basis). The method of processing the crude bauxitic kaolin can include refining the crude bauxitic kaolin by milling to produce a fine particle size or a coarse particle size bauxitic kaolin. In instances where a fine particle size bauxitic kaolin is desired, the crude bauxitic kaolin feed stream can have a nominal particle size diameter of 420 microns or less, as measured by a Microtrac Model S5300 Particle Size Analyzer.

The method of processing the crude bauxitic kaolin can include drying and/or calcining the kaolin to obtain kaolin free of surface moisture and/or calcined kaolin, respectively. Drying and/or calcining the bauxitic kaolin can be done prior to, during, and/or after refining milling. The method can also include mixing the bauxitic kaolin with a surface modifying agent. Suitable surface modifying agents are disclosed herein and mixing can be carried out during or after refining the crude bauxitic kaolin. In some embodiments, the bauxitic kaolin can be screened through a +200 mesh after milling to obtain a first screened fraction and a second screened fraction.

Methods for making compositions comprising the bauxitic kaolins are also disclosed. The method can include mixing a polymer or polymer composition with the bauxitic kaolin to form a mixture.

Additional advantages will be set forth in part in the description that follows or may be learned by practice of the aspects described below. The advantages described below will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the disclosure and together with the description, serve to explain the principles of the disclosure.

Figure 1 is a thermogravimetric analysis (TGA) curve showing the temperature shift during crystal (structure) water removal from bauxitic kaolin.

DETAILED DESCRIPTION

The term“comprising” and variations thereof as used herein is used synonymously with the term“including” and variations thereof and are open, non-limiting terms.

Although the terms“comprising” and“including” have been used herein to describe various embodiments, the terms“consisting essentially of’ and“consisting of’ can be used in place of“comprising” and“including” to provide for more specific embodiments and are also disclosed. As used in this disclosure and in the appended claims, the singular for s“a”, “an”,“the”, include plural referents unless the context clearly dictates otherwise. The disclosure of percentage ranges and other ranges herein includes the disclosure of the endpoints of the range and any integers provided in the range.

The term“calcined” as used herein refers to heat-treated kaolin to remove bound structure water and other volatiles from the kaolin’s surface and is synonymous with the term“volatile -free.” For bauxitic kaolin calcined at 1,000°C or above, the majority or all of bound structure water and volatiles are removed from the bauxitic kaolin.“Calcined basis” refers to an amount or fraction of a component remaining after kaolin has been

mathematically reduced to account for losses in weight expected to occur if the component had been calcined. Thus, 10 grams of a component containing 25% volatiles would be described as“7.5 g on a calcined basis.”

Disclosed herein are bauxitic kaolins and compositions comprising the same.

Methods of making and using the bauxitic kaolin are also described herein. Generally, the properties and uses of the bauxitic kaolin are dependent on attributes, such as particle size, particle size distribution, shape, alumina content, silica content, total alkali content (Na, K, Ca, Mg), impurity content such as FC2O3 or SO3 content, and texture of the individual particles and of agglomerates thereof.

“Bauxitic kaolin,” also referred to as“bauxitic clay,” refers to naturally occurring aluminum-silicate minerals containing alumina hydrate. In some instances, the alumina present in the bauxitic kaolin can be in the form of gibbsite (also referred to herein as mineral gibbsite, AI2O3, alpha-alumina trihydrate and/or monoclinic hydrated alumina kaolin) and boehmite. The bauxitic kaolin can include greater than 45% by weight (e.g.,

47% or greater, 50% or greater, 52% or greater, 54% or greater, 55% or greater, 58% or greater, 60% or greater, 65% or greater, 70% or greater, 72% or greater, 75% or greater, or 80% or greater, by weight) AI2O3 content (on a calcined basis). The AI2O3 content described herein is based on bauxitic kaolin calcined at 1,000°C or above. In some embodiments, the bauxitic kaolin includes 85% or less (e.g., 82% or less, 80% or less, 78% or less, 75% or less, 73% or less, 70% or less, 65% or less, 60% or less, 55% or less, or 50% or less by weight) AI2O3 content (on a calcined basis). In some embodiments, AI2O3 can be a major component in the bauxitic kaolin. For example, the bauxitic kaolin can include from 45% to 85% (e.g., from 45% to 80%, from 47% to 80%, or from 45% to 75% by weight) AI2O3 content (on a calcined basis). In general, crude bauxitic kaolin from which the bauxitic kaolins disclosed herein are derived can be found with high AI2O3 content. For example, the crude bauxitic kaolin can have an AI2O3 content of 47% or greater, 50% or greater, 55% or greater, 60% or greater, 65% or greater, 70% or greater, 75% or greater, or 80% or greater by weight (on a calcined basis).

As disclosed herein, crude bauxitic kaolin occurs throughout the world and the composition thereof varies from one location to another. In some cases, the crude bauxitic kaolin can be found in mines being found in Middle Georgia, East Georgia, and Arkansas.

The bauxitic kaolin includes kaolin in significant amounts, such as from 5% to 95% by weight. In some embodiments, the bauxitic kaolin can have a kaolin content of 90% by weight or less, 85% by weight or less, 80% by weight or less, 75% by weight or less, 70% by weight or less, 65% by weight or less, 60% by weight or less, 55% by weight or less,

50% by weight or less, 45% by weight or less, 40% by weight or less, 35% by weight or less, 30% by weight or less, 25% by weight or less, 20% by weight or less, 15% by weight or less, 10% by weight or less, or 5% by weight or less, based on the total weight of the bauxitic kaolin. In some embodiments, the bauxitic kaolin can have a kaolin content of greater than 5% by weight, such as 10% by weight or greater, 15% by weight or greater, 20% by weight or greater, 25% by weight or greater, 30% by weight or greater, 35% by weight or greater, 40% by weight or greater, 45% by weight or greater, 50% by weight or greater, 55% by weight or greater, 60% by weight or greater, 65% by weight or greater,

70% by weight or greater, 75% by weight or greater, 80% by weight or greater, 85% by weight or greater, 90% by weight or greater, or up to 95% by weight, based on the total weight of the bauxitic kaolin. In some embodiments, the bauxitic kaolin can have a kaolin content of from 5% to 95% by weight, from greater than 5% to 60% by weight, from 10% to 50% by weight, or from 15% to 45% by weight, based on the total weight of the crude bauxitic kaolin. The kaolin content of the bauxitic kaolin can be determined by X-ray fluorescence spectroscopy or by determining the loss-on-ignition value as measured by calcining the sample at 1,000°C for 1 hr in a furnace.

The bauxitic kaolin can also contain other minerals such as iron oxide, titanium oxide, and silicon oxide. When present, iron oxide can be in the form of goethite. The bauxitic kaolin can include 2 wt% or less Fe₂0₃ content. For example, the bauxitic kaolin can include an Fe203 content of from greater than 0% to 2% by weight, from 0.1 % to 2% by weight, or from 0.5% to 2% by weight, based on the total weight of the bauxitic kaolin. The Fc O i content of the bauxitic kaolin can be determined by X-ray fluorescence spectroscopy.

When present, titania minerals can be present in the bauxitic kaolin as anatase. The bauxitic kaolin can include 5 wt% or less titania content. For example, the bauxitic kaolin can include a titania content of from greater than 0% to 5% by weight, from 0.5% to 5% by weight, or from 1% to 5% by weight, based on the total weight of the bauxitic kaolin. The titania content of the bauxitic kaolin can be determined by X-ray fluorescence spectroscopy.

Other materials and/or impurities present in bauxitic kaolin can include alkali materials such as sodium oxide and potassium oxide.

The bauxitic kaolin disclosed herein can exhibit desirable loss on ignition. The loss on ignition value of the bauxitic kaolin has been shown herein to increase with increased AI2O3 content. The increased loss on ignition is demonstrated by the temperature shift for the crystal (structure) water removal indicated by the TGA curves shown in Figure 1. A high LOI value and higher temperature requirement for removing the crystal water during its exposure to heat can be advantageous for using the bauxitic kaolins in various flame retardant applications.

In some embodiments, the bauxitic kaolin can have a loss on ignition, measured by calcination at 1000°C for 1 hour, of at least 17%, such as at least 18%, at least 19%, at least 20%, at least 22%, at least 24%, at least 26%, at least 28%, or at least 30% by weight of the bauxitic kaolin. In some embodiments, the bauxitic kaolin can have a loss on ignition, measured by calcination at 1000°C for 1 hour, of 30% or less, 29% or less, 28% or less,

27% or less, 25% or less, 23% or less, 22% or less, 20% or less, 18% or less, or 17% or less, by weight of the bauxitic kaolin. In some embodiments, the bauxitic kaolin can have a loss on ignition, measured by calcination at 1000°C for 1 hour, of from 17% to 30%, from 18% to 28%, or from 17% to 25%, by weight of the bauxitic kaolin. The loss on ignition of the bauxitic kaolin is based on an anhydrous bauxitic kaolin sample, for example, calcined bauxitic kaolin. Specifically, the loss on ignition refers to the weight loss of raw bauxitic material when calcined at 1,000°C for 1 hr in a furnace. In some instances, the loss on ignition of bauxitic kaolin can be increased by removing at least a portion of the iron oxide, titanium oxide, or silica particles.

In general, crude bauxitic kaolin has a high AI2O3 content. The loss on ignition (LOI) value of the crude bauxitic kaolins from which the bauxitic kaolins disclosed herein are derived can be up to 28% loss by weight. For example, the loss on ignition, measured by calcination at l000°C for 1 hour, of at least 17%, such as at least 20%, at least 22%, at least 25%, at least 27%, at least 30%, or at least 32% by weight of the bauxitic kaolin.

The bauxitic kaolin can have a surface area of at least 100 m²/g, as determined by a Micrometries Gemini 2370 surface area analyzer. For example, the bauxitic kaolin can have a surface area of 100 m²/g or greater, 110 m²/g or greater, 120 m²/g or greater, 130 m²/g or greater, 140 m²/g or greater, 150 m²/g or greater, 160 m²/g or greater, 170 m²/g or greater, 180 m²/g or greater, 190 m²/g or greater, or 200 m²/g or greater, as determined by a Micrometries Gemini 2370 surface area analyzer. In some embodiments, the bauxitic kaolin can have a surface area of less than 250 m²/g, 230 m²/g or less, 220 m²/g or less, 210 m²/g or less, 200 m²/g or less, 190 m²/g or less, 180 m²/g or less, 170 m²/g or less, 160 m²/g or less, 150 m²/g or less, 130 m²/g or less, 120 m²/g or less, 110 m²/g or less, or 100 m²/g or less, as determined by a Micrometries Gemini 2370 surface area analyzer. In some embodiments, the bauxitic kaolin can have a surface area of from 100 m²/g to 250 m²/g, from 120 m²/g to 250 m²/g, from 140 m²/g to 250 m²/g, or from 150 m²/g to 230 m²/g.

The bauxitic kaolin disclosed herein can include a surface modifying agent. In some cases, the surface modifying agent can include a dispersant. The dispersant can include an organic dispersant such as an ammonia-based dispersant, a sulfonate dispersant, a carboxylic acid dispersant, or a polymeric dispersant. The polymeric organic dispersant can have a molecular weight of 10,000 Da or less, such as from 2,000 to 10,000 Da, from 3,000 to 8,000 Da, or from 3,000 to 5,000 Da. Specific examples of polymeric dispersants include a poly acrylate salt (such as ammonium poly acrylate or sodium poly acrylate), a poly alky lene glycol, a polyacrylamide, or a mixture thereof. When present, the organic dispersant can be in an amount of at least 0.05 wt% (e.g., from 0.05 to 3 wt%, from 0.1 wt% to 2.5 wt%, or from 0.5 to 1.5 wt%), based on the weight of the bauxitic kaolin.

In some cases, the dispersant can include an inorganic dispersant such as a phosphate or a silicate salt. Exemplary inorganic dispersants include a monophosphate salt, a pyrophosphate salt, a tripolyphosphate salt, a hexametaphosphate salt, an acid pyrophosphate salt, or a mixture thereof. Examples of phosphate salts include inorganic polyphosphates and pyrophosphates (which are actually a type of polyphosphate), sodium hexametaphosphate (SHMP), sodium tripolyphosphate (STPP), and tetrasodium pyrophosphate (TSPP), and examples of silicate salts include sodium silicate.

In some cases, the surface modifying agent can further include a pH modifier. The pH modifier can include an alkaline-based pH modifier such as soda ash, caustic soda, or combinations thereof. When present, the alkaline-based pH modifier can be in an amount such that an aqueous dispersion containing 78 grams or greater (such as from 78 to 85 grams) of the bauxitic kaolin/22 grams of water (equivalent to 78% or greater solids concentration in water) has a pH of at least 9.0 when measured at 20°C. For example, the pH of the dispersed mixture can be from 9.0 to 12.0, such as from 9.5 to 12.0 or from 9.5 to 11.0.

Preferably, the surface modifying agent includes an organic dispersant and an alkaline-based pH modifier. When both an organic dispersant and an alkaline-based pH modifier are used, the weight ratio between the organic dispersant and the alkaline-hased pH modifier can be from 1:10 to 1:1. For example, the weight ratio between the organic dispersant and the alkaline-based pH modifier can be 1:8 or greater, 1:7 or greater, 1:6 or greater, or 1:5 or greater. In some embodiments, the weight ratio between the organic dispersant and the alkaline-hased pH modifier can be 1:1 or less, 1:2 or less, 1:3 or less, 1:4 or less, or 1:5 or less. In some embodiments, the weight ratio between the organic dispersant and the alkaline-hased pH modifier can be from 1:10 to 1:1, from 1:8 to 1:1, from 1 :7 to 1 : 1 , from 1 :6 to 1:1 or from 1 :5 to 1 : 1.

The bauxitic kaolin disclosed herein can have a GE brightness (GEB) of at least 55%. For example, the bauxitic kaolin can have a brightness of 57% or greater, 58% or greater, 60% or greater, 62% or greater, 65% or greater, 67% or greater, 70% or greater,

72% or greater, 75% or greater, 78% or greater, 80% or greater, or 85% or greater. In some embodiments, the bauxitic kaolin can have a brightness of from 55% to 85%, from 55% to 80%, from 55% to 78%, or from 60% to 80%. As used herein, brightness is determined by the TAPPI standard method T452. The data are reported as the percentage reflectance to light of a 457 nm wavelength (GEB value).

Bauxitic Kaolin for Use in Carpet Backing and Other Polymeric Compositions

The bauxitic kaolins can be used in various applications depending on their average particle size and/or particle size distribution. In some embodiments, the particles in the bauxitic kaolin disclosed herein can have a coarse or granular particle size distribution. Particle size distribution (PSD) as used herein can be determined with the SEDIGRAPH 5100 particle size analyzer (Micromeritics Corporation) or a Microtrac Model S3500 Particle Size Analyzer on bauxitic kaolin in a fully dispersed condition in a standard aqueous medium, such as water. The median particle size d50 is the value determined in this way of the particle equivalent size diameter, at which there are 50% by weight of the particles that have an equivalent size diameter less than or equal to the d50 value and 50% by weight of the particles that have an e.s.d. greater than or equal to the d50 value.

In some embodiments, the coarse bauxitic kaolin can include particles having a particle size wherein at least 50% (such as at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, or at least 80%) by weight of the particles in the bauxitic kaolin have a particle diameter of 20 pm or greater, 25 pm or greater, 30 pm or greater, 35 pm or greater, 40 pm or greater, 44 pm or greater, 45 pm or greater, 48 pm or greater, 50 pm or greater,

52 pm or greater, 54 pm or greater, 55 pm or greater, 70 pm or greater, 72 pm or greater, or 75 pm or greater, or 80 pm or greater, or 85 pm or greater, as determined by a Microtrac Model S3500 Particle Size Analyzer. In some embodiments, at least 50% (such as at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, or at least 80%) by weight of the particles in the bauxitic kaolin have a particle diameter of 85 pm or less, 80 pm or less, 75 pm or less, 70 pm or less, 65 pm or less, 60 pm or less, 55 pm or less, 50 pm or less, 45 pm or less, 44 pm or less, 40 pm or less, 35 pm or less, 30 pm or less, 25 pm or less, or 20 pm or less. In some embodiments, at least 50% (at least 55%, at least 60%, at least 65%, at least 70%, or at least 75%) by weight of the particles in the bauxitic kaolin have a particle diameter of from 20 pm to 250 pm, from 35 pm to 250 pm, from 40 pm to 250 pm, from 44 pm to 250 pm, from 50 pm to 250 pm, from 55 pm to 250 pm, from 60 pm to 250 pm, from 44 pm to 200 pm, from 44 pm to 150 pm, from 25 pm to 150 pm, from 25 pm to 100 pm, from 25 pm to 75 pm, or from 40 pm to 75 pm, as determined by a Microtrac Model S3500 Particle Size Analyzer.

The coarse bauxitic kaolin can include particles having a particle size (d90) wherein 90% by weight of the particles have an e.s.d. less than or equal to the d90 value and 10% by weight of the particles have an e.s.d. greater than or equal to the d90 value. In some embodiments, the coarse bauxitic kaolin includes particles having a d90 particle size of 90 pm or greater, 95 pm or greater, 100 pm or greater, 105 pm or greater, 110 pm or greater, 115 pm or greater, 120 pm or greater, 125 pm or greater, 130 pm or greater, 135 pm or greater, or 140 pm or greater, as determined by a Microtrac Model S3500 Particle Size Analyzer. In some embodiments, the coarse bauxitic kaolin includes particles having a d90 particle size of about 200 pm or less, 190 pm or less, 180 pm or less, 170 pm or less, 160 pm or less, 150 pm or less, 145 pm or less, 140 pm or less, 135 pm or less, 130 pm or less, 125 pm or less, 115 pm or less, 110 pm or less, or 100 pm or less, as determined by a Microtrac Model S3500 Particle Size Analyzer. In some embodiments, the coarse bauxitic kaolin includes particles having a d90 particle size of from 95 pm to 250 pm, from 100 pm to 250 pm, from 115 pm to 250 pm, from 120 pm to 250 pm, from 125 pm to 250 pm, or from 125 pm to 200 pm, as determined by a Microtrac Model S3500 Particle Size Analyzer.

The coarse bauxitic kaolin can include particles having a particle size (dlO) wherein 10% by weight of the particles have an e.s.d. less than or equal to the dlO value and 90% by weight of the particles have an e.s.d. greater than or equal to the dlO value. For example, the coarse bauxitic kaolin includes particles having a dlO particle size of 4 pm or greater, 5 pm or greater, 6 pm or greater, 7 pm or greater, 8 pm or greater, 10 pm or greater, 12 pm or greater, 14 pm or greater, 15 pm or greater, 16 pm or greater, or 18 pm or greater, as determined by a Microtrac Model S3500 Particle Size Analyzer. In some embodiments, the coarse bauxitic kaolin includes particles having a dlO particle size of 25 pm or less, 24 pm or less, 22 pm or less, 20 pm or less, 18 pm or less, 15 pm or less, 12 pm or less, 10 pm or less, 8 pm or less, or 6 pm or less, as determined by a Microtrac Model S3500 Particle Size Analyzer. In some embodiments, the coarse bauxitic kaolin includes particles having a dlO particle size of from 4 pm to 25 pm, from 5 pm to 25 pm, or from 4 pm to 20 pm, as determined by a Microtrac Model S3500 Particle Size Analyzer.

Representative ranges for PSD and median particle size for the coarse bauxitic kaolin compositions disclosed herein are provided in Table 1.

Table 1

Table 2

The particle size distribution of the coarse bauxitic kaolin can comprise 55% or greater (such as 60% or greater, or 65% or greater) by weight of kaolin particles having a diameter of 44 pm or greater; 10% or greater (such as 20% or greater, 25% or greater, 30% or greater, or 40% or greater) by weight of the kaolin particles have a diameter of 74 pm or greater; 8 % or greater (such as 10% or greater, 15% or greater, 20% or greater, or 25% or greater) by weight of the kaolin particles having a diameter of 88 pm or greater; 2% or greater (such as 4% or greater, or 5% or greater) by weight of the kaolin particles having a diameter of 149 pm or greater. In some embodiments, the particle size distribution can be determined with a Sedigraph 5100 particle size analyzer.

In some cases, the particles in the coarse bauxitic kaolin can have a nominal particle size of 250 microns or less. The term“nominal” particle size, as used herein refers to the size of a particle capable of passing through a screen of a stated mesh size. The coarse bauxitic kaolin may be ground to a more finely divided particulate form so as to achieve the desired nominal particle size. For example, the coarse bauxitic kaolin may be ground to a nominal particle size of about 250 microns (60 mesh) or less prior to being incorporated into a composition in a flame-retardant effective amount in accordance with the present disclosure.

In some embodiments, the bauxitic kaolin disclosed herein can have a fine particle size distribution. The fine bauxitic kaolin can have a nominal particle size of 25 microns or less, such as 20 microns or less, 15 microns or less, or 10 microns or less.

The particle size distribution of the fine bauxitic kaolin can comprise at least 50% (such as at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, or at least 80%) by weight of kaolin particles having a particle diameter of 1.3 pm or greater, 1.5 pm or greater, 1.7 pm or greater, 1.8 pm or greater, 2.0 pm or greater, or 2.1 pm or greater, as determined by a Microtrac Model S3500 Particle Size Analyzer. In some embodiments, at least 50% (such as at least 55%, at least 60%, at least 65%, at least 70%, at least 75%, or at least 80%) by weight of the kaolin particles have a particle diameter of 2.5 pm or less, 2.3 pm or less, 2.2 pm or less, 2.1 pm or less, 2.0 pm or less, 1.5 microns or less, or 1.3 microns or less, as determined by a Microtrac Model S3500 Particle Size Analyzer. In some embodiments, at least 50% (at least 55%, at least 60%, at least 65%, at least 70%, or at least 75%) by weight of the kaolin particles have a particle diameter of from 1.3 pm to 2.5 pm, from 1.5 pm to 2.5 pm, from 1.5 pm to 2.3 pm, from 1.7 pm to 2.5pm, or from 1.7 pm to 2.3 pm, as determined by a Microtrac Model S3500 Particle Size Analyzer.

The particles in the fine bauxitic kaolin disclosed herein can have a d90 particle size of 5.5 pm or greater, 5.7 pm or greater, 6.0 pm or greater, 6.2 pm or greater, or 6.4 pm or greater, as determined by a Microtrac Model S3500 Particle Size Analyzer. In some embodiments, the particles in the fine bauxitic kaolin can have a d90 particle size of 7.5 pm or less, 7.0 mpi or less, 6.7 pm or less, 6.5 pm or less, or 6.4 pm or less, as determined by a Microtrac Model S3500 Particle Size Analyzer. In some embodiments, the particles in the fine bauxitic kaolin can have a d90 particle size of from 5.5 pm to 7.5 pm, from 5.7 pm to 7.5 pm, or from 6.0 pm to 7.0 pm, as determined by a Microtrac Model S3500 Particle Size Analyzer.

The particles in the fine bauxitic kaolin disclosed herein can have a dlO particle size of 0.2 pm or greater, 0.3 pm or greater, 0.4 pm or greater, 0.5 pm or greater, 0.6 pm or greater, or 0.7 pm or greater, as determined by a Microtrac Model S3500 Particle Size Analyzer. In some embodiments, the particles in the fine bauxitic kaolin can have a dlO particle size of 1.5 pm or less, 1.4 pm or less, 1.2 pm or less, 1.0 pm or less, 0.8 pm or less, 0.6 pm or less, or 0.5 pm or less, as determined by a Microtrac Model S3500 Particle Size Analyzer. In some embodiments, the particles in the fine bauxitic kaolin can have a dlO particle size of from 0.2 pm to 1.5 pm, from 0.4 pm to 1.2 pm, or from 0.5 pm to 1.0 pm, as determined by a Microtrac Model S3500 Particle Size Analyzer.

Representative ranges for PSD and median particle size for the fine bauxitic kaolin disclosed herein are provided in Table 2.

Table 2

The particle size distribution of the fine bauxitic kaolin can comprise 95% or greater (such as 97% or greater, or 99% or greater) by weight of kaolin particles having a diameter of less than 10 pm; 90% or greater (such as 92% or greater, 95% or greater, 97% or greater, or 99% or greater) by weight of the kaolin particles having a diameter of less than 5 pm; 60% or greater (such as 62% or greater, 63% or greater, 64% or greater, or 65% or greater) by weight of the kaolin particles having a diameter of less than 2 pm; 40% or greater (such as 42% or greater, 44% or greater, 45% or greater, or 46% or greater) by weight of the kaolin particles having a diameter of less than 1 pm; 20% or greater (such as 22% or greater, 25% or greater, 27% or greater, or 28% or greater) by weight of the kaolin particles having a diameter of less than 0.5 pm; 10% or greater (such as 12% or greater, 14% or greater, 15% or greater, or 16% or greater) by weight of the kaolin particles have a diameter of less than 0.3 mpi; and 5% or greater (such as 6% or greater, 8% or greater, 9% or greater, or 10% or greater) by weight of the kaolin particles having a diameter of less than 0.2 pm.

The fine bauxitic kaolin can also be characterized based on their mesh residue content. In some embodiments, the fine bauxitic kaolin can have a +325 mesh residue content of 50 ppm or less, such as 40 ppm or less, 30 ppm or less, 25 ppm or less, 20 ppm or less, or 15 ppm or less, by weight of the fine bauxitic kaolin. In some embodiments, the fine bauxitic kaolin can have a +325 mesh residue content of from 1 ppm to 50 ppm, from 1 ppm to 40 ppm, or from 1 ppm to 35 ppm, by weight of the fine bauxitic kaolin.

Methods

Methods for making a bauxitic kaolin are disclosed herein. The bauxitic kaolin can be derived from any crude bauxitic kaolin including processed or partially processed crude bauxitic kaolins. As discussed below, the selection of starting crude can guide the choice of additional processing steps one can add to the basic present method to achieve the desired particle size and/or particle size distribution.

In some embodiments, the method for making the bauxitic kaolin disclosed herein can include a drying step to reduce the moisture level of the kaolin. In some embodiments, the crude bauxitic kaolin can be dried prior to or during processing of the crude bauxitic kaolin. Drying the bauxitic kaolin may facilitate subsequent pulverization of the bauxitic kaolin. The crude bauxitic kaolin can be dried by spray drying, flash drying, rotary drying, or a combination thereof. The heated air stream can have a temperature of from about 600°F to about 1 ,000°F. After drying, the crude bauxitic kaolin can have a moisture level of less than 1.5% by weight, less than 1% by weight, less than 0.5% by weight, or less than 0.1% by weight. The bauxitic kaolin can be free of surface moisture. The phrase“free of surface moisture” is synonymous with the term“bone-dry” and refers to dried bauxitic kaolin that is free of surface moisture but not structure water (prior to calcination).

The bauxitic kaolin can also be calcined. Calcination can be carried out at a temperature and for a duration of time sufficient to convert hydrous kaolin to spinel and then a targeted percentage of the spinel to mullite. Calcination results in the removal of both surface moisture and structure/crystal water. Calcination temperature and residence time are a function of the process configuration utilized. In some embodiments, once dried, the calciner feed can be pulverized and then calcined at temperatures between 1050 to 1600°C, such as between 1050 to 1300°C. The calcination temperature is dictated by the desired level of product M.I. and process residence time. A fluxing agent can be added to the hydrous bauxitic kaolin prior to calcination. The dosage of the fluxing agent and the type of fluxing agent required are dependent on the hydrous kaolin feed morphology and its particle size distribution. In some case, the calcined bauxitic kaolin can contain an active flux cation in an amount of from 0.2% to 2.0%. Preferred fluxing agents are alkali and alkaline earths of boron oxides, silicates, phosphates, alkali and alkaline earth metal salts of carbonates and bicarbonates, or their combinations.

The method for making the bauxitic kaolin disclosed herein can include refining, such as by classifying the crude bauxitic kaolin to produce a crude bauxitic feed stream. “Classifying” as used herein refers to a process for removing oversize particles from the crude bauxitic kaolin. Classifying can include imparting a force to the crude bauxitic kaolin such as by shearing, crushing, pulverizing, milling, or such the like to reduce the particle size of the crude bauxitic kaolin. In some embodiments, the methods described herein can include classifying the crude bauxitic kaolin by crushing to produce a finer particle size feed stream having a nominal particle size of less than 4 mm. For example, the method can include crushing the crude bauxitic kaolin to produce a bauxitic kaolin feed stream having a nominal particle size of less than 3.8 mm, less than 3.5 mm, less than 3.3 mm, or less than 3.0 mm. The crude bauxitic kaolin can be crushed using a rock crusher.

In some embodiments, the crude bauxitic kaolin can be classified by pulverizing to produce a finer particle size. For example, the crude bauxitic kaolin can be pulverized to produce a finer particle size having a nominal particle size of less than 250 microns. For example, the method can include pulverizing the crude bauxitic kaolin to produce a bauxitic kaolin feed stream having a nominal particle size of less than 245 microns, less than 240 microns, less than 230 microns, less than 220 microns, or less than 200 microns. The bauxitic kaolin can be pulverized using a disc pulverizer. In some embodiments, the method for making the bauxitic kaolin can include both crushing and pulverizing the crude bauxitic kaolin.

The crushed and/or pulverized crude bauxitic kaolin can be screened, for example, through a mesh to obtain a desired nominal particle size. For example, the particles can be screened through a 60 mesh screen or a 100 mesh screen.

In some embodiments, the crude bauxitic kaolin can be classified by grinding to produce a finer particle size having a nominal particle size of less than 150 microns. For example, the method can include grinding the crude bauxitic kaolin to produce a bauxitic kaolin feed stream having a nominal particle size of less than 145 microns, less than 140 microns, less than 135 microns, less than 130 microns, or less than 125 microns. The bauxitic kaolin can be ground using a cage mill and roller mill in combination as the grinding equipment. In some cases, the cage mill/roller mill combination can provide the target particle size on finished product on a production scale. Other grinding equipment such as media mills (a rod mill or a ball mill) or a hammer mill equipped with a pre-drying step can also be used to obtain bauxitic kaolin having the target particle size. In some embodiments, the ground crude bauxitic kaolin can be screened through a 200 mesh screen.

For the purpose of obtaining a bauxitic kaolin with very fine particle size distribution (for example an average target particle size of about 1.0 to 1.2 microns, as measured using a Sedigraph particle size analyzer for use in plastics), the crude bauxitic kaolin can be classified by pulverizing to produce a finer particle size having an average particle size of less than 425 microns (40 mesh). The pulverized bauxitic product with about 40 mesh particle size can be milled, such as using a jet mill to obtain finer particle size bauxitic kaolin. Other fine milling technologies such as air classified mechanical pulverizers (Bauer mill, ACM mill or similar equipment) may also be utilized for this purpose.

As discussed herein, generating large amounts of fines from the bauxitic kaolin materials for use in applications such as carpet fillers, is preferably avoided. In some cases, ground bauxitic kaolin containing high amounts of fines (i.e., more than 45% by weight of particles is <325 mesh) may not be applicable for carpet pre-coat and adhesive applications, due to the viscosity increase imparted to the polymers employed for this purpose. Thus, it is preferable to reduce the amount of fines below about 45% by weight or less. It is believed that higher alumina containing bauxitic kaolins (i.e., >50% AI2O3, >60% AI2O3, or >70% AI2O3) can be selected and carefully selecting the pulverization equipment to avoid generating excessive amount of fines during processing can reduce the amount of fines generated. Using the methods disclosed herein, the yield of coarse bauxitic kaolin can be 60% or greater, 65% or greater, 75% or greater, 80% or greater, 85% or greater, or 90% or greater.

The methods for making the bauxitic kaolin disclosed herein can include mixing the bauxitic kaolin with a surface modifying agent. Mixing can include making the bauxitic kaolin feed stream into a slurry with the aid of a surface modifying agent as disclosed herein, through the use of a high-energy mixer. The surface modifying agent can be added to the crude bauxitic kaolin in dry form. For example, the surface modifying agent can be added to the bauxitic kaolin before or during the classifying (e.g., crushing, pulverizing, and/or grinding) step. Preferably, the surface modifier is incorporated before or during the grinding step (i.e., metering chemicals to the plant feeder) to obtain a more uniform distribution.

The surface modifying agent added to the crude bauxitic kaolin can provide additional fluidity to facilitate mixing/dispersing the bauxitic kaolin into a polymer phase. Without wishing to be bound by theory, dispersing bauxitic kaolin into a polymer phase (such as a latex in carpet backing formulation) can be challenging because the kaolin is typically mildly acidic and does not readily wet-out and blend into a polymer solution. Bauxitic kaolin filler particles tend to settle, thus does not forming a homogeneous slurry even in the presence of excessive mechanical agitation. This can cause technical hurdles for not being able to utilize the pulverized bauxitic kaolin in carpet backing, even if the pulverized product meets a desired particle size distribution. Furthermore, the viscosity of bauxitic kaolin filled latex slurry can increase when stored for extended period of time. As a result, it can become a challenge to pump the slurry from holding vessels.

It is believed that addition of a surface modifying agent (such as a dispersant and a pH modifier) can disperse the bauxitic kaolin into a polymer composition. While both organic and inorganic dispersants may be used for this purpose, organic short chain polyacrylate dispersants with about 3,000 to 4,000 molecular weight are the preferred option. It is also believed that a pH regulator such as soda ash or preferably caustic soda can be beneficial when used in combination with an organic dispersant. Using such a combination of dispersant package can result in a dispersed and stable bauxitic kaolin slurry that is compatible with the polymer phase. Surprisingly, it was found that the surface modifying agents can provide a well dispersed and stable bauxitic kaolin slurry even after aging.

In some embodiments, the aqueous dispersion can have a Brookfield viscosity of 1,000 cps or greater, 1,100 cps or greater, 1,200 cps or greater, 1,400 cps or greater, 1,500 cps or greater, 1,700 cps or greater, 1,800 cps or greater, 1,900 cps or greater, 2,000 cps or greater, 2,100 cps or greater, 2,200 cps or greater, 2,300 cps or greater, 2,400 cps or greater, or 2,500 cps or greater using a #2 spindle at 20 rpm and 20°C. In some embodiments, the aqueous dispersion can have a Brookfield viscosity of 2,500 cps or less, 2,400 cps or less, 2,300 cps or less, 2,200 cps or less, 2,000 cps or less, 1,800 cps or less, 1,600 cps or less, 1,500 cps or less, or 1,200 cps or less, using a #2 spindle at 20 rpm and 20°C. In some embodiments, the aqueous dispersion can have a Brookfield viscosity of from 1,000 cps to 2,500 cps, from 1,200 cps to 2,500 cps, from 1,500 cps to 2,500 cps, from 1,000 cps to 2,300 cps, from 1,500 cps to 2,300 cps, using a #2 spindle at 20 rpm and 20°C. The aqueous dispersion of bauxitic kaolin can have a solids content of 78% or greater, 80% or greater, 82% or greater, or 84% or greater by weight of the dispersion. The solids content of the bauxitic kaolin mixture can be determined by a CEM Smart Turbo microwave moisture analyzer.

The methods for making the bauxitic kaolin can further include other refining processes such as degritting, bleaching, floatation, ozonation, centrifugation, selective flocculation, magnetic separation, filtering, re-dispersing, spray drying, pulverizing, or combinations thereof. Methods for gritting, bleaching, floatation, ozonation, centrifugation, selective flocculation, magnetic separation, filtering, re-dispersing, spray drying, pulverizing, or combinations thereof are known to one of ordinary skill in the art.

Method of Use

The bauxitic kaolin can be advantageously employed in several applications wherein bauxitic kaolin can be used. In some embodiments, the bauxitic kaolin can be used as a flame retardant filler in construction materials. Such construction materials can include carpeting, roofing, wire and cable, and coatings. The bauxitic kaolin can also be used as a filler in plastic materials, including engineering plastics, polyolefins, toys, and other such materials made from plastic and requiring flame retardant properties. The bauxitic kaolin can also be used in other applications, such as in the making of activated alumina, highly reactive metakaolin, adsorbent, catalyst, alum, or in agriculture applications.

In certain embodiments, the bauxitic kaolin can be used as a flame retardant in carpet backings. Carpet backing formulations are known in the art and can include water, a dispersing agent, a base such as sodium hydroxide, a latex component, a surfactant , a thickener (such as high molecular weight poly acrylate thickeners), a defoamer, the bauxitic kaolin as disclosed herein, an additional filler.

In certain embodiments, the bauxitic kaolin can be used as adsorbents. In these embodiments, the bauxitic kaolin can include meta-bauxitic kaolin, that is bauxitic kaolin calcined at 450°C or greater or 500°C or greater at soak time of 15 minutes or greater, preferably 30 minutes or greater. The meta-bauxitic kaolin that is calcined at temperatures above 450°C may still include a portion of structure water. In some instances, the meta- bauxitic kaolin can have a minus 8 mesh particle size. However, other particle size meta- bauxitic kaolin (including from submicron up to 8 x 14 mesh or even coarser) can also suitably be used as adsorbents. In some embodiments, the meta-bauxitic kaolin can have a particle size of 5 mm or less, 4 mm or less, 3 mm or less, 2.5 mm or less, 2 mm or less, 1.5 mm or less, 1 mm or less, 0.75 mm or less, 0.5 mm or less, 0.4 mm or less, 0.3 mm or less, 0.2 mm or less, or 0.1 mm or less. In some embodiments, the meta-bauxitic kaolin can have a d90 particle size of about 100 pm or less, 95 pm or less, 90 pm or less, or 85 pm or less as determined by a Microtrac Model S3500 Particle Size Analyzer. In some embodiments, the meta-bauxitic kaolin can comprise particles having a d90 particle size of from 80 pm to 5 mm, from 80 pm to 2.5 mm, from 85 pm to 2.5 mm, from 80 pm to 100 pm, from 85 pm to 100 pm, or from 85 pm to 95 pm, as determined by a Microtrac Model S3500 Particle Size Analyzer. Such particle size range can be obtained by using the crushing, milling and sizing technologies that are used by those skilled in the art.

The meta-bauxitic kaolin can have a surface area of 100 m²/g or greater, such as 110 m²/g or greater, 120 m²/g or greater, 130 m²/g or greater, 140 m²/g or greater, 150 m²/g or greater, 160 m²/g or greater, 170 m²/g or greater, 175 m²/g or greater, 180 m²/g or greater, 185 m²/g or greater, 190 m²/g or greater, 195 m²/g or greater, or 200 m²/g or greater. In certain embodiments, the meta-bauxitic kaolin can have a surface area of from 170 to 250 m²/g, 175 to 220 m²/g, from 175 to 200 m²/g or from 100 to 250 m²/g.

The meta-bauxitic kaolin can adsorb ions, preferably anions from solutions including arsenic, selenium, phosphate or combinations thereof.

In some embodiments, the composition can comprise the bauxitic kaolin in an amount of 10 wt% or greater. For example, the composition can comprise the bauxitic kaolin particles in an amount of 15 wt% or greater, 20 wt% or greater, 25 wt% or greater, 30 wt% or greater, 35 wt% or greater, 40 wt% or greater, 45 wt% or greater, 50 wt% or greater, 55 wt% or greater, 60 wt% or greater, 65 wt% or greater, 70 wt% or greater, 75 wt% or greater, 80 wt% or greater, 85 wt% or greater, or 90 wt% or greater. In some embodiments, the composition can comprise the bauxitic kaolin filler in an amount of 90 wt% or less, 85 wt% or less, 80 wt% or less, 75 wt% or less, 70 wt% or less, 65 wt% or less, 60 wt% or less, 55 wt% or less, 45 wt% or less, 40 wt% or less, 35 wt% or less, or 30 wt% or less. The bauxitic kaolin disclosed herein can be present in any amount within a range derived from the above values. For example, the bauxitic kaolin can be present in an amount from 5 wt% to 90 wt%, from 5 wt% to 80 wt%, from 5 wt% to 70 wt%, from 5 wt% to 60 wt%, from 10 wt% to 60 wt%, or from 10 wt% to 50 wt%. The latex component in the compositions can be made from various polymer materials such as, for example, from ethylene vinyl acetate, carboxylated styrene-butadiene latex copolymer, styrene butadiene latex, a butadiene methyl methacrylate latex, an acrylic latex, an acrylic copolymer, a styrene copolymer, butadiene acrylate copolymer, a polyolefin hotmelt, polyurethane, polyolefin dispersions and/or emulsions, or a combination thereof. In some examples, the latex component can include Styrofan® NX 4628 provided by BASF. Styrofan® NX 4628 is a styrene-butadiene latex, generally used to incorporate nontraditional fillers and additives into carpet backing systems.

As disclosed herein, the compositions for example for use as carpet backing optionally comprise one or more additional filler materials. Exemplary additional fillers that can be incorporated into the composition can include calcium carbonate, fly ash, residual by products from the depolymerization of Nylon 6 (also referred to as ENR co-product), recycled calcium carbonate (e.g., reclaimed calcium carbonate), aluminum trihydrate, talc, nano-clay, barium sulfate, barite, barite glass fiber, glass powder, glass cullet, metal powder, alumina, hydrated alumina, clay, magnesium carbonate, calcium sulfate, silica, glass, fumed silica, carbon black, graphite, cement dust, feldspar, nepheline, magnesium oxide, zinc oxide, aluminum silicate, calcium silicate, titanium dioxide, titanates, glass microspheres, chalk, calcium oxide, and any combination thereof. The additional filler can be included in the carpet backing in an amount of from 5% to 50% by weight. In some embodiments, aluminum trihydrate is not used as an additional filler in the composition.

The dispersing agent can include polycarboxylate copolymers commercially available from BASF under the trade name SOKALAN^®, but may also comprise other polycarboxylate copolymers such as carboxylic acid copolymers, acrylic acid

homopolymers, carboxymethyl cellulose, and nonionic copolymers such as

polyvinylpyrrolidone .

The bauxitic kaolin can also be used as a flame retardant filler in plastic

compositions. The plastic composition can include a polymer, the bauxitic kaolin disclosed herein, and an additional filler. In some embodiments, the plastic composition comprises the bauxitic kaolin in an amount of 10 wt% or greater. For example, the plastic composition can comprise the bauxitic kaolin in an amount of 15 wt% or greater, 20 wt% or greater, 25 wt% or greater, 30 wt% or greater, 35 wt% or greater, 40 wt% or greater, 45 wt% or greater, 50 wt% or greater, 55 wt% or greater, 60 wt% or greater, 65 wt% or greater, 70 wt% or greater, 75 wt% or greater, 80 wt% or greater, 85 wt% or greater, or 90 wt% or greater. In some embodiments, the plastic composition comprise the bauxitic kaolin filler in an amount of 90 wt% or less, 85 wt% or less, 80 wt% or less, 75 wt% or less, 70 wt% or less, 65 wt% or less, 60 wt% or less, 55 wt% or less, 45 wt% or less, 40 wt% or less, 35 wt% or less, or 30 wt% or less. The bauxitic kaolin disclosed herein can be present in any amount within a range derived from the above values. For example, the bauxitic kaolin can be present in an amount from 5 wt% to 90 wt%, from 5 wt% to 80 wt%, from 5 wt% to 70 wt%, from 5 wt% to 60 wt%, from 10 wt% to 60 wt%, or from 10 wt% to 50 wt%.

The polymer in the plastic compositions may be a thermoset or a thermoplastic. Suitable polymer materials include polyvinyl chloride (PVC), poly alky lene such as polypropylene (PP) or polyethylene (PE), polyethylene terephthalate (PET), acrylonitrile butadiene styrene (ABS), nylon, or a combination thereof. The additional filler can include a filler as disclosed herein, such as talc, CaCCh, wollastonite, aluminum trihydrate or combinations of these. The plastic composition may include additives, such as pigments, stabilizers, lubricants and other conventional additives used in thermoset or thermoplastic polymers.

As disclosed herein, the bauxitic kaolin can be used to provide improved flame retardance to materials such as, carpet backings and plastics. A limiting oxygen index (LOI) test, as described in ASTM D2863-13 (also described by Fenimore and Martin in Modem Plastics, November 1966), can be used to determine the flame retardancy of the materials. The limiting oxygen index refers to the maximum oxygen concentration at which the flame on a sample self-extinguishes within one minute. In brief, this procedure directly relates flame retardancy to a measurement of the minimum percentage concentration of oxygen in an oxygen: nitrogen mixture which permits the sample to burn. Thus, a higher LOI is indicative of a higher degree of flame retardancy.

In some embodiments, compositions disclosed herein comprising the bauxitic kaolin can have a limiting oxygen index of at least 25, such as at least 27, at least 28, at least 29, at least 30, at least 32, at least 34, at least 35, at least 36, at least 37, at least 38, or even higher, as determined by in ASTM D2863-13. In some embodiments, the compositions can have a limiting oxygen index, as determined by in ASTM D2863-13, of 40 or less, 38 or less, 37 or less, 36 or less, or 35 or less. In some embodiments, the compositions can have a limiting oxygen index, as determined by in ASTM D2863-13, of from 21 to 40, from 21 to 38, from 23 to 36, or from 25 to 35. In some cases, the limiting oxygen index may vary, depending on the amount of flame retardant incorporated into the particular sample. The compositions comprising the bauxitic kaolin may also show a comparable, similar or improved burn property, tuft bind, and delamination over a calcium carbonate filled or ATH filled composition. The compositions also provide improved fire resistance as determined by the pill test. The pill test is used to determine whether a carpet is sufficiently fire resistant for use in the home. The test includes igniting a methenamine pill, which is placed in the center of a nine-inch by nine-inch carpet specimen. If the flame spreads to within one inch of a metal template containing an eight-inch diameter hole, which is placed on top of the carpet specimen prior to igniting the pill, the specimen fails. If the flame does not spread to within one inch of the metal template, then the specimen passes. For a residential carpet, as described above, to be saleable, at least seven out of eight specimens must pass the test. In some embodiments, the burn area for compositions comprising the bauxitic kaolin is less than 1 cm.

In addition to enhanced flame retardant property, the bauxitic kaolin also allow higher loading when incorporated into the polymer matrix as a reinforcing filler.

Polymer/bauxitic kaolin composites can also provide improved mechanical properties, such as higher tensile strength and tensile modulus, as compared to neat polymer or other known fillers currently utilized in such composites. Without wishing to be bound by theory, it is believed that the enhancement in tensile strength and tensile modulus can be attributed to the uniform dispersion of ultra-fine bauxitic kaolin within the polymer matrix and the strong interaction between polymer and bauxitic kaolin. Surface treatments can be used with the bauxitic kaolin which can further enhance the dispersion of filler within the polymer matrix and in turn enhance the interaction of filler with the polymer matrix. Mechanical properties of polymer/bauxitic kaolin composites can be further enhanced, as a direct result of surface treatment of filler as well.

By way of non-limiting illustration, examples of certain embodiments of the present disclosure are given below.

Examples

The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the compositions and/or methods claimed herein are made and evaluated, and are intended to be purely exemplary and are not intended to limit the scope of the disclosure. Unless indicated otherwise, parts are parts by weight, temperature is in °C or is at ambient temperature, and pressure is at or near atmospheric.

Example 1: Preparation of a bauxitic kaolin as flame retardant fillers

Background: In the Middle Georgia kaolin clay deposits,“bauxitic kaolin” formations can be found in significant quantities. The bauxitic kaolins can be encountered in the upper, in between or at the bottom of kaolinite layers which can be distinguished from the typical kaolin clay by their distinct color and appearance. The term“bauxitic kaolin” refer to such naturally occurring aluminum-silicate minerals containing bauxitic minerals such as gibbsite, boehmite (alumina hydrates) deposited alongside the kaolinite mineral, as a major constituent expressed as AI2O3. In general, bauxitic kaolins can be differentiated from the traditional kaolin by their AI2O3 and loss-on-ignition (LOI) content. Kaolin generally contains about 45% by weight or less AI2O3 (on a calcined basis) and 14% by weight or less LOI (as determined by the weight loss upon firing the raw bauxitic kaolin at 1,000°C). Bauxitic kaolin can contain greater than 45% by weight AI2O3 (such as at least 50% by weight AI2O3) and greater than 14% by weight (such as 17% by weight LOI). Bauxitic kaolin can contain iron oxide, titania-ferrous impurities, silica, mica, and other impurities in varying amounts. Generally, these bauxitic kaolins are either discarded or left in the ground or sold as raw materials to the other end users such as those of making alumina-silicate refractory materials, ceramic proppants, and cement.

In this example, methods of preparing and utilization of bauxitic kaolins are disclosed. For example, the bauxitic kaolins can be used as flame -retardant fillers for construction materials including, but not limited to, carpeting, roofing, wire and cable, coatings, adhesives, and other such materials that require flame retardant properties. The bauxitic kaolins can also be used in plastic materials including, but not limited to, engineering plastics, polyolefins, toys, plastic articles and other such materials made from plastic and requiring flame retardant properties. Also exemplified herein are methods for pulverizing the bauxitic kaolin suitable for use in such applications. Further exemplified herein are methods of surface modification and stabilization of bauxitic kaolin slurries, by treating pulverized bauxitic kaolin in dry form with at least one pH modifier and one organic dispersant to render the final slurry pH above 9.5.

Method

Description of Bauxitic Kaolin Mineral: Bauxitic kaolin samples used in this example were obtained from various mines located within the Middle Georgia mineral deposits. X-Ray Fluorescence (XRF) and Thermogravimetric Analysis (TGA) results of the bauxitic kaolins, having varying AI2O3 content, are presented in Table 1 below.

Table 1 : Description of crude bauxitic kaolin.

The crude bauxitic kaolins can be found with as high as 80% AI2O3 (on a volatile free basis) and 27 to 28% loss on ignition (LOI) content within the Middle Georgia mineral resources. In general, the crude bauxitic kaolins used in this example comprise AI2O3 contents of from 60% up to 80%. Also shown in Table 1, the LOI value increases with increased AI2O3 content and there is a temperature shift for the crystal (structure) water removal, as indicated by the TGA curves (Figure 1), i.e. the higher AI2O3 content, the higher temperature required for water removal. Such a high LOI value and higher temperature requirement for removing the crystal water during its exposure to heat would be advantageous for using these bauxitic kaolins in various flame retardant applications.

X-Ray Diffraction (XRD) analysis shows that the bauxitic kaolin which are found along with the kaolin clays within the Middle Georgia mineral resources are mainly the mineral gibbsite (Al(OH)₃), also known as alpha-alumina trihydrate or monoclinic hydrated alumina clay, along with boehmite and kaolinite, and smaller amounts of other impurities such as anatase and goethite.

Process Development - Bench Scaling: Bauxitic kaolin samples were first dried in an oven followed by homogenization. The samples were then crushed below 4 mm top size using a lab rock crusher and then pulverized to below a nominal 60 mesh particle size using a disc pulverizer. Tables 4 and 5 show XRF analysis results and other physical properties of two processed bauxitic kaolin samples with two different AI₂O₃ content.

Table 2: Description of crude bauxitic kaolin from back calculation.

The data presented in Table 2 shows that the amount of fines (<325 mesh fractions) is reduced when the crude bauxitic kaolin with higher AI2O3 content (i.e., 76% AI2O3) is used as the starting raw material, as compared to lower AI2O3 content (i.e., 60.7% AI2O3). Care must be taken during the pulverization step to avoid generating large amounts of fines (<325 mesh particles) on pulverized bauxitic kaolin materials, particularly as carpet backing fillers. Ground bauxitic kaolins containing high amounts of fines (i.e., more than 45% <325 mesh fractions) may not be applicable for pre-coat and adhesive applications, due to the viscosity increase imparted to the polymers employed for this purpose. Thus, it is desirable to reduce the amount of fines to about 45% by weight or less. As demonstrated above, this can be accomplished by selecting higher alumina containing bauxitic kaolins (i.e., >70% AI2O3) and selecting the pulverization equipment to avoid generating excessive amounts of fines during processing. It would also be possible to minimize amount of fines by post particle classification using conventional equipment such as air cyclones, air sifters etc.

Process Development - Plant Scaling: Following the bench scale process development, a plant trial was carried out to determine if the process is scalable and to produce a large sample with a target particle size of nominal <100 mesh product. The plant trial equipment consists of a cage mill and roller mill in combination as the grinding equipment. As can be seen from the data in Table 3, the cage mill/roller mill combination provided the target particle size on finished product and accordingly can be the preferred grinding equipment on a production scale. Flowever, other grinding equipment such as media mills (a rod mill or a ball mill) or a hammer mill equipped with a pre-drying step can also be utilized for achieving the same.

Plant Trial Results: The plant trial results are summari ed in Table 3 below. As shown, a ground bauxitic kaolin product with a target particle size of <100 mesh could be achieved on a whole grind product from the full scale production equipment. The whole grind sample had 40% <325 mesh particle size.

Table 3: Properties of crude bauxitic kaolin from plant trials.

Table 4: XRF properties of crude bauxitic kaolin from plant trials.

Sample C - Plant pulverized product, whole grind

Sample D - Plant pulverized product, screened, >200 mesh

Sample E - Plant pulverized product, screened, <200 mesh To find out if the amount of 325 mesh fines could be further reduced, the whole grind product was screened through a 200 mesh air sifter (dry screen). The physical properties of coarse (+200 mesh fraction) and fines (-200 mesh fraction) products obtained from dry screening step are also included in Table 3 for comparison with the whole grind product. As shown, the amount of 325 mesh fractions can be reduced from 40% on a whole grind sample to 32% on a dry screened coarse fractions. So, this approach could be used advantageously to reduce amount of 325 mesh fines, if the amount of such fines exceeds 45% on the bauxitic kaolin product that is developed as part of this disclosure. As mentioned before, controlling the amount of fines can prevent any detrimental impact of elevated viscosity on carpet backing formulation in the presence of bauxitic kaolin.

The XRF data presented in Table 4 show that the whole grind product has 78.8%

AI2O3 content. AI2O3 content is increased up to 80.7% on the screen coarse fractions, indicating that the coarser particles contain higher amount of bauxite component, while the screen fines fractions consist of bauxitic kaolin/kaolin component.

The data also show that the bauxitic kaolins have surprisingly very high surface area. As shown, the whole grind product from the plant trial has a 204 m²/g surface area. Such a high surface area is a unique property for the bauxitic kaolin that can be particularly beneficial for its use in applications such as adsorbents or producing highly surface active aluminas and reactive metakaolins.

Bauxitic Kaolin Slurry Make-down and Properties: One of the challenges to overcome when incorporating bauxitic kaolin into the polymer phase (such as a latex in carpet backing formulation) is that it is typically mildly acidic and does not readily wet-out and blend into the polymer solution. Bauxitic kaolin filler particles tend to settle, thus they do not form a homogeneous slurry even in the presence of excessive mechanical agitation. This causes significant technical hurdles for not being able to successfully utilize the pulverized bauxitic kaolin in carpet backing, even if the pulverized product meets the desired particles size distribution. Another and equally important concern is that the viscosity of bauxitic kaolin filled latex slurry would have a tendency to increase when stored for extended period of time. As a result, it becomes very difficult to pump the slurry from holding vessels.

This example demonstrates that it is advantageous to use a dispersant and a pH modifier in combination to effectively disperse the bauxitic kaolin when incorporating the bauxitic kaolin into the polymer composition as the flame retardant filler. Although known organic and inorganic dispersants may be used for this purpose, organic short chain polyacrylate dispersants with about 3,000 to 4,000 molecular weight are preferred. It was found that the short chain polyacrylates (e.g., Sokalan brand) provide a stable dispersion of the filler/latex slurry as determined by the viscosity of filler and filler/latex.

Table 5: Bauxitic kaolin slurry make-down results: plant trial whole grind Sokalan CPN 43/caustic soda dispersant.

It was found that a pH regulator such as soda ash or preferably caustic soda can be beneficial when used in combination with an organic short chain polyacrylate dispersant. Using such a combination of dispersant package results in a well dispersed and stable bauxitic kaolin slurry that is compatible with the polymer phase. Surprisingly, it was found that highly stable bauxitic kaolin slurries can be obtained when the sodium

polyacrylate/caustic combination is employed as the dispersant package at 9.5 pH or above.

The effects of using sodium polyacrylate (organic dispersant)/ sodium

hexametaphosphate (inorganic dispersant) and soda ash as a trio dispersant package was also investigated. The trio dispersant package typically contains about 55% sodium polyacrylate/l5% sodium hexametaphosphate and 30% soda ash. This dispersant package along with using additional soda ash for pH regulation provides a well dispersed bauxitic kaolin slurry in the initial phase. However, after 24 hours aging of slurry, it was observed that there is a drift on pH towards more acidic levels, when the initial slurry is made down at pH close to neutral levels (~7.0 to 7.5 pH).

One of the shortcomings of using soda ash as the pH regulator is that it is a relatively weak base, so to obtain a very high pH slurry (i.e., pH>9.5), high dosages are to be used. To overcome these issues such as the drift on slurry pH, it was found that using the combination of sodium polyacrylate and caustic at pH>9.5 would provide a well dispersed and stable bauxitic kaolin slurry after aging.

This example further shows that the use of combination dispersants described above for the surface modification of bauxitic kaolin on a dry form. This would be an even greater advantage, for example, for the carpet backing users, as they would be receiving surface modified bauxitic kaolin as ready to use dry form. The typical active sodium

polyacrylate/caustic soda blend ratio is 65/35, although other blend ratios could also be employed, provided that the pH of surface modified bauxitic kaolin is maintained at 9.5 or above and sufficient amount of sodium polyacrylate dispersant is utilized. It has been found that the sodium poly acrylate dispersant dosage can be in the range of about 0.05 to 3.0% by weight generally to achieve the desired surface modification at such pH level. Normally, the range of about 0.5 to 1.5% weight of sodium polyacrylate was found to be satisfactory dispersant dosage for bauxitic kaolins.

Surface modifying agents can be added to the bauxitic kaolin particles before or during the grinding step. Typically, more uniform distribution of surface modifier onto the particles can be achieved if the surface modifier is introduced before or during the grinding step (i.e., metering chemicals to the plant feeder). However, with the proper design of mixing and chemical addition equipment, it is also quite possible to modify the bauxitic kaolin surface after grinding step. It should be noted that there are quite a number of well- established and widely used mixing equipment to achieve this.

Table 6 below provides a summary of dry surface modification results and slurry properties on resulting surface modified bauxitic kaolin. As shown, it would be possible to obtain a slurry at 78.2% solids with a suitable Brookfield viscosity (1,850 cps) without adding any additional dispersant, if the ground bauxitic kaolin is modified using a 65/35 sodium polyacrylate/caustic blend at pH=9.6. This required 21 lbs/ton of overall dispersant dosage (total of both sodium polyacrylate and caustic).

Table 6: Bauxitic kaolin dry surface modification and slurry make-down results: Plant trial whole grind - dry modification with Sokalan CPN 43/caustic soda dispersant.

It is noted that although noticeable improvements have been observed when using the surface modifier dispersant (combination of sodium polyacrylate and caustic) to the carpet backing formulations, as compared to not using any modifier at all, it would be more beneficial to modify the surface of bauxitic kaolin prior to incorporating into the polymer phase to obtain improved compatibility with the polymer compositions and improved benefits as the flame retardant filler.

Carpet Backing Application: Carpet backing formulations and application test results are summarized below. Table 7: Bauxitic kaolin 500 load carpet formulation testing.

Coating #2a - 60 mesh (dry add) Coating #2b - >200 mesh (dry add)

Coating #2c - whole grind (dry add)

The carpet backing formula chosen for lower loadings and solids was successfully dispersed into a stable composition. The solid level target was 78%. The films created for LOI were all smooth and no cracking occurred. This lower solids amount can be moved higher. The <60 mesh and whole grind bauxitic kaolin samples had LOI numbers of 31.4 and 30 respectively and the control was 35.7. The bauxitic kaolin product shows an improved burn property over a regular calcium carbonate (200W, a ground calcium carbonate as supplied by IMERYS). The ratio of bauxitic kaolin and calcium carbonate can be raised to potentially improve burn properties. Carpet samples were coated to test for tuft bind and delamination. These numbers show the tuft bind properties are generally similar to the controls.

The results confirm that bauxitic kaolin has the flame retardant properties, as indicated by the“limited oxygen index, LOI” value. In addition to the LOI value,“pill test” results also indicated that the bauxitic kaolin can be used as the partial or full replacement with the incumbent ATH filler. In the case of“pill test” results, the diameter of the burn area for the bauxitic kaolin filled latex was 0.937 cm, whereas the ATH filled latex had a 1.01 cm diameter. So, overall both limited oxygen index and pill test results confirm that the inventive bauxitic kaolin product does have the flame retardant properties.

Cured latex films prepared using the control filler (ATH, alumina trihydrate) and inventive filler (bauxitic kaolin) as the flame retarding filler were obtained. Good and smooth latex films without any deficiencies were obtained using bauxitic kaolin as the filler.

Example 2: Fine Milled Bauxitic Kaolin as Flame Retardant in Engineering Plastics For the purpose of obtaining a bauxitic kaolin product with very fine particle size distribution (to an average target particle size of about 1.0- 1.2 pm, as measured using a Sedigraph 5100 particle size analyzer), the plant pulverized product with about 40 mesh top particle size, as obtained from the previous plant trials, was subjected to jet milling tests. Table 8: Fine Milled Bauxitic Kaolin.

For the jet milling test, a Flosokawa Alpine AFG 400 model pilot unit was utilized. Table 8 above summarizes physical properties of fine jet milled product. As shown, bauxitic kaolin product with an average particle size of 1.18 microns can be obtained using the jet milling technology. Note also that the surface area of fine milled bauxitic kaolin is 173.4 m²/g. The particle size at d9o, dso and dio as measured using a Microtrac Particle Size analyzer is presented in the table as well. As shown, average particle size of fine milled product from the Microtrac analyzer was determined to be 2.1 pm.

XRF data on the fine milled bauxitic kaolin from jet milling is also presented in Table 9 below. As shown, the jet milled product has 74.4% AI2O3 and 23.7% LOI content.

Table 9: XRF properties of fine milled bauxitic kaolin from jet milling.

Sample I: Bauxitic kaolin, jet milled

In summary, the results confirm that it would be possible to obtain a bauxitic kaolin product with ultrafine particle size distribution by using a jet mill for pulverization. Other fine milling technologies such as air classified mechanical pulverizers (Bauer mill, ACM mill or similar equipment) could also be utilized for this purpose. The jet mill, however, may provide a finer particle size distribution as compared to the other commercial equipment currently utilized for fine mill grinding due to its operating principle (i.e. using a stream of high velocity air jet for particle disintegration combined with using a mechanical classifier for the top size control).

Such bauxitic kaolins with ultrafine particle size distribution can be used advantageously as the flame retardant filler in many different engineering plastics including PVC, PE, PP and nylon. In addition to enhanced flame retardant property, the inventive bauxitic kaolin would also allow higher loading when incorporated into the polymer matrix as a reinforcing filler. Polymer/bauxitic kaolin composites would also provide superior mechanical properties, such as higher tensile strength and tensile modulus, as compared to neat polymer or other known fillers currently utilized in such composites.

The enhancement in tensile strength and tensile modulus may be attributed to the uniform dispersion of ultra-fine bauxitic kaolin particles within the polymer matrix and the strong interaction between polymer and bauxitic kaolin particles. Various surface treatments, for example with an organic dispersant, can be used for the bauxitic kaolin which can further enhance the dispersion of filler within the polymer matrix and in turn enhance the interaction of filler with the polymer matrix. Mechanical properties of polymer/bauxitic kaolin composites can be further enhanced, as a direct result of surface treatment of the filler as well.

The examples provided herein demonstrate methods of preparing and utilizing bauxitic kaolin as, for example, flame -retardant fillers for use in for example,“construction materials.” Such construction materials include, but are not limited to, carpeting, roofing, wire and cable, coatings, and other such construction materials that require flame retardant properties. The bauxitic kaolin can also be used in“plastic materials.” For example, plastic materials include, but are not limited to, engineering plastics, polyolefins, toys, plastic articles and other such materials made from plastic and requiring flame retardant properties.

Pulverization methods for obtaining products with varying particle size distribution from very coarse pulverized to ultra-fine milled products for different flame retardant application requirements are also exemplified. Surface modification methods for making the bauxitic kaolins compatible with polymer compositions are also disclosed.

There are other potential areas for utilizing bauxitic kaolin. For example, the bauxitic kaolins can be used for making products for other applications such as activated alumina, highly reactive meta-kaolin, absorbents, catalysts, for alum production, or in agriculture applications.

Example 3: Bauxitic Kaolin as Adsorbent

Process Development: Bauxitic kaolin samples were first dried in an oven followed by homogenization. The samples were then crushed below 4 mm top size using a lab rock crusher and then pulverized to below a nominal 60 mesh particle size using a disc pulverizer. The pulverized samples were calcined at 500°C at various soak times in a muffle furnace to obtain a meta-bauxitic kaolin. Tables 10 and 11 show the physical properties and XRF analysis results of processed bauxitic kaolin samples calcined at 500°C at various soak times.

It should be noted here that, in this example, the minus 60 mesh particle size was selected as an example to demonstrate the adsorption capability of bauxitic kaolin. As part of this disclosure, a wide range of particle size from submicron particle size up to 8 x 14 mesh or even coarser meta-bauxitic kaolin can be obtained and used as an adsorbent. Such particle size range can be obtained by using the crushing, milling and sizing technologies that are used by those skilled in the art. Granulated form of meta-bauxitic kaolin can also be used as adsorbent and granulated particles can be obtained by using the various granulation technologies.

Table 10. Physical properties of bauxitic kaolin calcined at 500°C at various time intervals.

The data presented in Table 10 show that the calcined bauxitic kaolin at meta-kaolin temperature has surprisingly very high surface area. As shown, the surface area of calcined bauxitic kaolin (termed here as meta-bauxitic kaolin or meta-BxK) is in the range from 176.2 up to 195.6 m²/g. Such a high surface area is a unique property for the meta-bauxitic kaolin and can be particularly beneficial for its use in applications such as adsorbents or producing high surface active aluminas and reactive meta-kaolins. The data presented in Table 10 also show that the Microtrac particle size is consistent across the calcination times tested. As shown, the d^ of meta-bauxitic kaolin is 89.1 to 91.1 microns, while its dso is 22.4-23.2 microns.

Table 11. XRF analysis of bauxitic kaolin calcined at 500°C at various time intervals.

The XRF data presented in Table 11 show that the AI2O3 content of meta-bauxitic kaolin is 67.1-72.2%, while its LOI content ranges from 8.85% up to 16.4% depending on the calcination time employed. The loss-on-ignition (LOI) of meta-bauxitic kaolin is decreased with increasing soak times from 15 minutes up to 60 minutes. Adsorbent Testing: To demonstrate the adsorbent capability of meta-bauxitic kaolin, a set of phosphate adsorption tests were carried out and the results are presented in Table 12 below. Experimental procedure for phosphate adsorption testing is described below:

Experimental Procedure : Stock solution: 3.714 g of ammonium dihydrogen phosphate (NH₄)H₂R0₄ per 1 liter deionized water.

1. The sample/adsorbent was weighed into a 200 ml“tall” glass beaker.

2. A magnetic stirrer was added to the weighed sample.

3. 100 ml of“contaminant’71000 ppm phosphorous solution was added to the sample.

4. The sample mixture was stirred on a stir plate for one hour.

5. The resulting sample mixture was then filtered through a #2 Whatman filter paper (24 cm diameter filter paper) in which all of the mixture was added to the filter paper at once).

6. 30 grams of the filtrate was weighed into centrifuge tubes and centrifuged for a total time of 12 minutes at 15,000 rpm in an IEC centrifuge.

7. A clear top layer was formed and subsequently removed from the centrifuge tubes with a pipet since decanting would disturb the settlement.

8. The clear pipetted top layer was diluted and analyzed by ICP (ARL 3410) for

phosphorous; dilution: 5 ml into 100 ml (20 dilution factor).

Table 12. Phosphate adsorption of meta-bauxitic kaolin calcined at 500°C.

% Phosphate Adsorption

As can be seen from the data in Table 12, phosphate adsorption capacity of meta- bauxitic kaolin increased with increasing amounts of adsorbent used. The phosphate adsorption on to the meta-bauxitic kaolin was about 10% at 1 g BxK in 100 mL water, while it gradually increased with increasing adsorbent addition reaching up to 99.9% with 20 g bauxitic kaolin in 100 mL water. The phosphate adsorption reaches to a plateau at 30 minutes soak time and beyond, indicating that a 30 minutes soak time would be sufficient for forming an efficient meta- bauxitic kaolin as adsorbent.

This example demonstrates the adsorbent capability of meta-bauxitic kaolin. Meta- bauxitic kaolin can be used as an adsorbent for other ions such as arsenic, selenium, and such the like.

The compositions and methods of the appended claims are not limited in scope by the specific compositions and methods described herein, which are intended as illustrations of a few aspects of the claims and any compositions and methods that are functionally equivalent are intended to fall within the scope of the claims. Various modifications of the compositions and methods in addition to those shown and described herein are intended to fall within the scope of the appended claims. Further, while only certain representative materials and method steps disclosed herein are specifically described, other combinations of the materials and method steps also are intended to fall within the scope of the appended claims, even if not specifically recited. Thus, a combination of steps, elements, components, or constituents may be explicitly mentioned herein; however, other combinations of steps, elements, components, and constituents are included, even though not explicitly stated.

Claims

What is claimed is:

1. A bauxitic kaolin having an AI2O3 content greater than 50% to 85% by weight on a calcined basis, a loss on ignition of at least 17% by weight, and a surface area of at least 100 m²/g, as determined by a Micrometries Gemini 2370 particle size analyzer.

2. The bauxitic kaolin of claim 1 , wherein the AI2O3 content of the bauxitic kaolin is greater than 60% by weight or greater than 70% by weight.

3. The bauxitic kaolin of claim 1 or 2, wherein the bauxitic kaolin has a nominal particle size diameter of 250 microns or less, as measured by a Microtrac Model S3500 Particle Size Analyzer.

4. The bauxitic kaolin of any one of claims 1-3, having a particle size distribution as measured by a Microtrac Model S3500 Particle Size Analyzer, wherein at least 55% of the particles by weight have a diameter of 44 microns or greater.

5. The bauxitic kaolin of any one of claims 1-4, wherein:

2% or greater of the particles by weight have a diameter of 149 microns or greater; 8% or greater of the particles by weight have a diameter of 88 microns or greater; and

10% or greater of the particles by weight have a diameter of 74 microns or greater.

6. The bauxitic kaolin of any one of claims 1-5, wherein:

2% or greater of the particles by weight have a diameter of 149 microns or greater; 20% or greater of the particles by weight have a diameter of 88 microns or greater; and

30% or greater of the particles by weight have a diameter of 74 microns or greater.

7. The bauxitic kaolin of any one of claims 1-6, wherein at least 60% or at least 65% of the particles by weight have a diameter of 44 microns or greater.

8. The bauxitic kaolin of any one of claims 1-7, wherein:

2% or greater of the particles by weight have a diameter of 149 microns or greater; 25% or greater of the particles by weight have a diameter of 88 microns or greater; 40% or greater of the particles by weight have a diameter of 74 microns or greater; and

60% or greater of the particles by weight have a diameter of 44 microns or greater.

9. The bauxitic kaolin of any one of claims 1-8, wherein the bauxitic kaolin has a median particle diameter (d₅o) of from 25 to 75 pm, as measured on a Microtrac Model S5300 Particle Size Analyzer.

10. The bauxitic kaolin of any one of claims 1-9, wherein the bauxitic kaolin has a median particle diameter (d₅o) of 50 pm or greater, as measured on a Microtrac Model S5300 Particle Size Analyzer.

11. The bauxitic kaolin of any one of claims 1-10, wherein the bauxitic kaolin has an average surface area of at least 200 m²/g, as determined by a Micrometries Gemini 2370 surface area analyzer.

12. The bauxitic kaolin of any one of claims 1-11, wherein the bauxitic kaolin has a loss on ignition of from 17% to 30% by weight.

13. The bauxitic kaolin of any one of claims 1-12, further comprising a surface modifying agent.

14. The bauxitic kaolin of any one of claims 1-13, wherein the surface modifying agent comprises a dispersant.

15. The bauxitic kaolin of claim 14, wherein the dispersant comprises an organic dispersant and an alkaline-based pH modifier.

16. The bauxitic kaolin of claim 15, wherein the organic dispersant comprises a poly acrylate.

17. The bauxitic kaolin of claim 15 or 16, wherein the organic dispersant is present in an amount of from 0.05% to 3% by weight of the bauxitic kaolin.

18. The bauxitic kaolin of any one of claims 15-17, wherein the organic dispersant is present in an amount of from 0.5% to 1.5% by weight of the bauxitic kaolin.

19. The bauxitic kaolin of any one of claims 15-18, wherein the alkaline-based pH modifier comprises caustic soda.

20. The bauxitic kaolin of any one of claims 15-19, wherein the organic dispersant and alkaline-based pH modifier are in a weight ratio of from 1 : 10 to 1:1.

21. The bauxitic kaolin of any one of claims 15-20, wherein the organic dispersant and alkaline-based pH modifier are in a weight ratio of from 1:5 to 1:1.

22. The bauxitic kaolin of any one of claims 15-21, wherein the alkaline-based pH modifier is present in an amount such that an aqueous dispersion containing 78 grams or greater of the bauxitic kaolin and 22 grams of water has a pH of at least 9.0 when measured at 20°C.

23. The bauxitic kaolin of claim 22, wherein the aqueous dispersion has a Brookfield viscosity of from 1000 cps to 2500 cps using a #2 spindle at 20 rpm and 20°C.

24. The bauxitic kaolin of any one of claims 1-23, wherein the bauxitic kaolin is free of surface moisture.

25. The bauxitic kaolin of any one of claims 1-24, wherein the bauxitic kaolin is calcined.

26. A composition comprising the bauxitic kaolin of any one of claims 1-25.

27. The composition of claim 26, further comprising a latex.

28. The composition of claim 27, wherein the latex is a styrene butadiene latex.

29. The composition of claim 26-28, wherein the composition has a Brookfield viscosity of 1000 cps or less using a #3 spindle at 20 rpm and 20°C.

30. The composition of claim 26-29, wherein the composition has a limiting oxygen index of at least 27, as determined by ASTM D2863-13.

31. An article comprising the composition of any one of claims 26-30.

32. The article of claim 31, wherein the article is a carpet backing.

33. The article of claim 31 or 32, wherein the article does not include additional alumina trihydrate.

34. A method of processing a crude bauxitic kaolin having an AI2O3 content greater than 50% by weight (on a calcined basis), the method comprising:

refining the crude bauxitic kaolin to form a bauxitic kaolin of any one of claims 1- 25,

wherein refining the crude bauxitic kaolin comprises milling.

35. The method of claim 34, wherein the AI2O3 content of the crude bauxitic kaolin is greater than 60% by weight.

36. The method of any one of claims 34-35, further comprising mixing the bauxitic kaolin with a surface modifying agent during or after refining the crude bauxitic kaolin.

37. The method of claim 36, wherein the surface modifying agent comprises an organic dispersant and an alkaline-based pH modifier.

38. The method of any one of claims 34-37, further comprising screening the bauxitic kaolin through a +200 mesh after refining to obtain a first screened fraction and a second screened fraction.

39. The method of claim 38, wherein at least 65% by weight of the particles in the first screened fraction have a diameter of 44 microns or greater.

40. The method of any one of claims 38-39, wherein the particles in the first screened fraction have an AI2O3 content of 75% or greater by weight.

41. The method of any one of claims 38-40, wherein the AI2O3 content of the particles in the first screened fraction is from 50% to 85% by weight.

42. A method of making a composition comprising:

mixing a latex with the bauxitic kaolin according to any one of claims 1-25 to form a mixture.

43. The method of claim 42, wherein the latex is a styrene butadiene latex.

44. The method of claim 42 or 43, wherein the mixture has a pH of at least 9.

45. A bauxitic kaolin having a particle size distribution, wherein

the bauxitic kaolin has a nominal particle size diameter of 10 microns or less and a +325 mesh residue content of 20 ppm or less, as determined by a Sedigraph 5100 Particle Analyzer.

46. A bauxitic kaolin having a particle size distribution, wherein

the bauxitic kaolin has a nominal particle size diameter of 25 microns or less and an average surface area of at least 170 m²/g as determined by a Sedigraph 5100 Particle Analyzer.

47. The bauxitic kaolin of claim 45 or 46, wherein:

at least 92% of the particles by weight have a diameter of less than 5 microns; at least 65% of the particles by weight have a diameter of less than 2 microns; at least 45% of the particles by weight have a diameter of less than 1 micron; and at least 27% of the particles by weight have a diameter of less than 0.5 micron.

48. The bauxitic kaolin of any one of claims 45-47, wherein the bauxitic kaolin has an AI2O3 content of greater than 50% by weight (on a calcined basis).

49. The bauxitic kaolin of claim 48, wherein the AI2O3 content is greater than 60% by weight.

50. The bauxitic kaolin of any one of claims 45-49, wherein the AI2O3 content is from greater than 50% to 85% by weight.

51. The bauxitic kaolin of any one of claims 45-50, having a median particle diameter (d₅o) of 2 microns or less, as determined by a Sedigraph 5100 Particle Analyzer.

52. The bauxitic kaolin of claim 51 , wherein the median particle diameter is from 1 to 2 microns, as determined by a Sedigraph 5100 Particle Analyzer.

53. The bauxitic kaolin of any one of claims 45-52, wherein the bauxitic kaolin has a loss on ignition of from 17% to 30% by weight.

54. The bauxitic kaolin of any one of claims 45-53, wherein the bauxitic kaolin has a GE Brightness of at least 55.

55. The bauxitic kaolin of any one of claims 45-54, further comprising a surface modifying agent.

56. The bauxitic kaolin of claim 55, wherein the surface modifying agent comprises a dispersant.

57. The bauxitic kaolin of claim 56, wherein the dispersant comprises an organic dispersant.

58. The bauxitic kaolin of claim 57, wherein the organic dispersant comprises a poly acrylate.

59. A composition comprising the bauxitic kaolin of any one of claims 45-58.

60. The composition of claim 59, further comprising a polymer.

61. The composition of claim 59 or 60, wherein the polymer is selected from polyesters, polyamides, rubbers, polyacrylics, epoxy polymers, polyurethanes, ethylene and propylene copolymers, polyvinyl chlorides, polyolefins, polystyrenes, or a mixture thereof.

62. An article comprising the composition of any one of claims 59-61.

63. The article of claim 61, wherein the article is a plastic material.

64. A method of processing a crude bauxitic kaolin, the method comprising:

providing a bauxitic kaolin feed stream having a nominal particle size diameter of

420 microns or less, as measured by a Microtrac Model S5300 Particle Size Analyzer; and refining the bauxitic kaolin feed stream to form the bauxitic kaolin of any one of cl aims 45-58,

wherein refining the bauxitic kaolin feed stream comprises milling.

65. The method of claim 64, wherein the bauxitic kaolin has an average surface area of at least 170 m²/g.

66. The method of any one of claims 64-65, wherein the crude bauxitic kaolin has an AI2O3 content of greater than 50% by weight (on a calcined basis).

67. The method of any one of claims 64-66, wherein the AI2O3 content of the crude bauxitic kaolin is from 65% to 80% by weight.

68. The method of any one of claims 64-67, further comprising mixing the bauxitic kaolin with a surface modifying agent.

69. A method of making a composition comprising:

mixing a polymer and the bauxitic kaolin according to any one of claims 45-58 to form a mixture.

70. The method of claim 69, wherein the polymer is selected from polyesters, polyamides, rubbers, polyacrylics, epoxy polymers, polyurethanes, ethylene and propylene copolymers, polyvinyl chlorides, polyolefins, polystyrenes, or a mixture thereof.

71. An adsorbent comprising meta-bauxitic kaolin having a surface area of at least 100 m²/g, preferably at least 130 m²/g, more preferably at least 170 m²/g, as determined by a Micrometries Gemini 2370 particle size analyzer.

72. The adsorbent of claim 71, wherein the surface area is from 100 m²/g to 200 m²/g, preferably from 120 m²/g to 200 m²/g, more preferably from 170 m²/g to 200 m²/g.

73. The adsorbent of claim 71 or 72, wherein the meta-bauxitic kaolin have a particle size of 8 x 14 mesh or less or 2.5 mm or less, or from 85 pm to 2.5 mm.

74. The adsorbent of any one of claims 71-73, wherein the d90 particle size is from 85 pm to 95 pm, as determined by a Microtrac Model S3500 Particle Size Analyzer.