WO2019009930A1 - Produits de diatomite calcinés par flux d'opaline blanche - Google Patents

Produits de diatomite calcinés par flux d'opaline blanche Download PDF

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Publication number
WO2019009930A1
WO2019009930A1 PCT/US2018/014514 US2018014514W WO2019009930A1 WO 2019009930 A1 WO2019009930 A1 WO 2019009930A1 US 2018014514 W US2018014514 W US 2018014514W WO 2019009930 A1 WO2019009930 A1 WO 2019009930A1
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Prior art keywords
product
physical component
opal
cristobalite
crystalline silica
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PCT/US2018/014514
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English (en)
Inventor
Peter E. Lenz
Scott K. Palm
George A. Nyamekye
Bradley S. HUMPHREYS
Qun Wang
Kara Linn EVANOFF
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Ep Minerals, Llc
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Publication of WO2019009930A1 publication Critical patent/WO2019009930A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/02—Loose filtering material, e.g. loose fibres
    • B01D39/06—Inorganic material, e.g. asbestos fibres, glass beads or fibres
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
    • B01J20/14—Diatomaceous earth
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30—Processes for preparing, regenerating, or reactivating
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30—Processes for preparing, regenerating, or reactivating
    • B01J20/3078—Thermal treatment, e.g. calcining or pyrolizing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/30—Processes for preparing, regenerating, or reactivating
    • B01J20/3085—Chemical treatments not covered by groups B01J20/3007 - B01J20/3078
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2239/00—Aspects relating to filtering material for liquid or gaseous fluids
    • B01D2239/04—Additives and treatments of the filtering material
    • B01D2239/0471—Surface coating material

Definitions

  • This disclosure concerns flux-calcined biogenic silica products, and more specifically, white, bright flux-calcined diatomite products suitable for use as filtration media, absorbents, carriers, or functional additives in paint, plastics, plastic film, adhesives, sealants, elastomers, personal care products or as ingredients in additive manufacturing and comprising low or non-detectable levels of crystalline silica and Silica Documentation (as defined herein), as well as related test methods and formulations.
  • Diatomaceous earth also called diatomite or kieselgur
  • DE Diatomaceous earth
  • kieselgur is a naturally- occurring sedimentary rock containing primarily the skeletal remains (also called frustules) of diatoms, a type of single-celled plant generally found in water, such as lakes and oceans.
  • Diatomite has been used for many years in a variety of manufacturing processes and applications, including use as a filtration media, a carrier, an absorbent and as a functional filler.
  • Diatomite as it naturally occurs, contains a mixture of the diatom frustules themselves, as well as other minerals, such as clays, volcanic ash, feldspars or quartz, which were deposited through sedimentary processes into the lake or ocean habitats of the living diatoms.
  • the diatom frustules when formed, are composed of an amorphous, hydrated biogenic silica called opal- A.
  • biogenic silica as silicon dioxide produced by a life form.
  • Common life forms that produce biogenic silica include diatoms, radiolaria, sponges, bamboo, rice plants or horsetails.
  • diatomite frustules do not contain any crystalline silica, but the other sediments contained within diatomite can include crystalline silica in the form of quartz, the main component of silica sand. Quartz is almost universally found in marine (salt water) deposits of diatomite, but some lacustrine (fresh water) deposits of diatomite are free of quartz or contain quartz grains of sufficient size that they can be removed during processing.
  • the opal-A can, over time, become partially dehydrated and can, in a series of stages, convert from opal-A to forms of opal with more short-range molecular order and containing less water of hydration, such as opal-CT and opal-C. Over very long periods of time and under suitable conditions, opal- CT and opal-C can convert to quartz.
  • the natural weathering process of opal-A in the Monterrey diatomite formation in California has been described by Eichhubl and Behl among others.
  • Opal-A, opal-CT and opal-C are individually or collectively often referred to as opal, vitreous silica or amorphous silica.
  • diatomite was employed as a pigment in cave paintings in Europe that date back as far as 40,000 years ago. Modern industrial use of diatomite began in the mid-to-late 1800's and expanded early in the 20th century when it was discovered that the filtration properties of the material could be modified through thermal treatment.
  • Straight-calcining almost always produces a change in the color of natural diatomite, from an off-white color to a pink color. The extent of this color change can be correlated with the iron content of the diatomite.
  • Straight-calcining generally is effective in producing products with low to medium permeabilities in the range of about 0.1 to about 0.6 darcy. In some cases, the permeability of straight-calcined products can be increased beyond these levels, up to about one darcy, through the removal of the fine fraction of particles contained in the calcined product, through separation processes, such as air classification.
  • Flux-calcining often changes the color of natural diatomite from off-white to a bright white color or sometimes to a brighter, less pink color. Flux-calcining can lead to much greater agglomeration of particles, and is generally used to produce products with permeabilities ranging from about 0.8 darcy to over ten darcy.
  • Products comprising straight-calcined or flux-calcined diatomite find widespread use in micro-filtration applications.
  • Natural diatomite products which are dried but not heated to the point where particles agglomerate, are sometimes used as alternatives to flux-calcined diatomite products in functional additive applications, particularly in coatings. Through selective mining processes and through careful drying and classification of the ore, natural diatomite products can be produced with tint and brightness properties that are acceptable in coatings applications. However, there are some significant differences between natural functional additive products and flux-calcined diatomite products, including the following:
  • Flux-calcined products contain a lower free moisture content, as the flux- calcining process completely removes surface moisture and brightens the product, whereas, drying a natural ore to a very low surface moisture content can result in a decline in the brightness and tint qualities of the product.
  • Very low free moisture is important when minerals are incorporated into products in which exposure to elevated temperatures can result in the liberation of water from the diatomite. For example, the liberation of water from diatomite after incorporation of the diatomite in thermoplastics materials, can result in the formation of undesirable bubbles in products, such as plastic film;
  • Flux-calcined products generally possess superior (low values) tint and higher brightness than natural products
  • crystalline silica which are generally lower, and may not be present in detectable levels, in natural diatomite products.
  • Opal-A which contains about 4 to 6 wt % water of hydration, converts to opal-C or opal-CT, which contains about 0.2 to 1 wt % water of hydration.
  • Opal-C or opal-CT if exposed to further high temperatures, can convert to a mineral phase traditionally characterized as cristobalite or, under certain conditions, quartz, which are crystalline forms of silicon dioxide that contain no water of hydration.
  • Cristobalite can also be formed during volcanism or through industrial processes such as the thermal processing of quartz. Cristobalite formed through the heating and cooling of quartz does not evolve from the dehydration of opaline raw materials, but rather through a reconstructive crystalline phase change at high temperature. [0018] During thermal processing, any quartz contained in the diatomite can also undergo a transition to cristobalite. Generally, quartz does not convert to cristobalite when diatomite ores are calcined in the absence of a fluxing agent but may convert to cristobalite when diatomite containing quartz is processed in the presence of a flux.
  • Products comprising straight-calcined and flux-calcined diatomite products comprise a number of attributes, including physical and chemical characteristics and regulatory support and hazard communications features. Certain of the physical characteristics which are commonly used to describe or characterize these products include the particle size distribution, the diatom assemblage (species of diatoms from which the frustules are derived), the packed or centrifuged wet density of the material, the brightness and tint of the material and a number of other characteristics which are known to those with a knowledge of the state of the art.
  • Products comprising straight-calcined and flux-calcined diatomite products can also be characterized by a number of chemical or compositional attributes, including the mineralogy, crystalline silica content, bulk chemistry and extractable chemistry for a number of substances, including iron, calcium, antimony, lead, chromium, arsenic and others.
  • straight-calcined and flux-calcined diatomite products also comprise regulatory or technical support features, such as certificates of analysis and Safety Data Sheets (SDS). Certificates of analysis are documents produced that include certification of certain characteristics agreed-upon by the supplier and the customer which may include almost any characteristic of interest to the customer. Safety Data Sheets, generally required by national governments worldwide and by international agreements, include
  • compositional information about the products and health hazard warnings are primarily designed to include information about hazards, exposure limits and the safe handling of materials.
  • Safety Data Sheets and their predecessor documents, such as the US Material Safety Data Sheets (MSDS) have, for many years, contained information about hazardous components of materials used in the workplace, such as crystalline silica, as the potential risks of silicosis from chronic inhalation of crystalline silica have been known for many years. Since 1987, when the International Agency for Research on Cancer determined that crystalline silica, in the form of cristobalite, quartz or tridymite, was a probable human carcinogen, many governments have required that warnings about crystalline silica contents above detection limits or certain exposure limits be included on Safety Data Sheets.
  • Silica Documentation includes one or more of the following: regulatory support document(s), hazard disclosure(s), Safety Data Sheet(s), label(s), product label(s), product bar code(s), certificates of analysis or other electronic or printed forms of data which document or disclose crystalline silica content, or the absence of crystalline silica in the content, of a product that includes diatomite.
  • the absence of crystalline silica is disclosed in Silica Documentation by either an explicit statement or an absence of crystalline silica (for example, cristobalite, quartz, tridymite) from the product contents identified by the Silica Documentation.
  • This disclosure concerns products, comprising flux-calcined diatomite.
  • the products possess properties which make the products appropriate for use as filtration medium/media, absorbents, carriers, functional additives in paint, plastics, plastic films, adhesives, sealants, elastomers, personal care products or other formulated compositions.
  • the properties of interest include, but are not limited to the following:
  • Celatom products are made by EP Minerals, LLC. Celite products are made by Imerys. Clarcel products are made by Ceca.
  • flatting efficiency was calculated as the percent reduction in 85° sheen for a waterborne latex paint (PVC 51) compared to a paint of the same formulation but without diatomite.
  • Celatom products are made by EP Minerals, LLC. Celite and Diafil proc ucts are made by Imerys. Dicalite products are made by Dicalite Minerals Corp.
  • Products comprising conventional physical components and novel Silica Documentation.
  • the conventional physical components include straight-calcined or flux-calcined diatomite.
  • the diatomite may include flux-calcined diatomite (diatomite ore processed with a fluxing additive to produce flux-calcined diatomite).
  • the fluxing additive used to process the diatomite may include one or more of the following fluxing additives or mixtures thereof: sodium carbonate, sodium chloride, sodium sesquicarbonate, sodium borate, sodium aluminate, or other sodium-based fluxes.
  • the products have very low or non- detectable levels of crystalline silica which can be characterized by optical properties which are superior to the optical properties disclosed by Lenz et al. and which previously have not been found in the public domain.
  • Such products may optionally comprise Silica Documentation comprising data developed through use of a method which distinguishes opal-C and/or opal-CT (if both opal-C and opal-CT phases are present in material they are treated collectively, herein, as if they are part of one phase) from cristobalite and which (method) has a detection limit as low as 0 wt % cristobalite to 0.5 wt %, depending on the mineralogy of the DE.
  • One such method is the LH Method disclosed by Lenz et al.
  • the term "detection limit" means the lowest quantity of a substance that can be distinguished from absence of that substance.
  • opal-C Consistent with Lenz et al., differentiation between opal-C and opal-CT is not attempted in the presently disclosed invention, and, if both phases are present, they are treated collectively as if they were part of one phase.
  • opal-C is used in the present disclosure to mean opal-C and/or opal-CT, unless indicated otherwise by the context in which it is used.
  • a product comprises a physical component that includes diatomite.
  • the physical component may have less than 1 wt % crystalline silica, as determined by a method which distinguishes between opal-C and cristobalite.
  • An absolute value of a* for the physical component plus an absolute value of b* for the physical component may be no more than 5.
  • the physical component may have no more than 1 wt % loss on ignition.
  • the absolute value of a* for the physical component plus the absolute value of b* for the physical component may be from 2.0 to 3.8. In a refinement, the absolute value of a* for the physical component plus the absolute value of b* for the physical component may be from 2.3 to 3.8.
  • the crystalline silica content of the physical component by weight may be less than 0.5 wt %, less than 0.3 wt % or less than 0.1 wt %.
  • the physical component may have an L* value of 89 to 97.1. In a refinement, the physical component may have an L* value of 89 to 95.
  • the physical component may have a d95 of no more than 50 ⁇ .
  • the physical component may have a CWD of no more than 0.40 g/ml.
  • the physical component may have a Hegman value of 0.5 to 7.
  • the crystalline silica content of the physical component by weight is greater as measured according to one or more Traditional Methods than as measured according to the method that differentiates between opal-C and cristobalite.
  • the product may further comprise Silica
  • Documentation that discloses the crystalline silica content present in the physical component as measured according to the method that differentiates between opal-C and cristobalite.
  • the method that differentiates between opal-C and cristobalite may be the LH Method.
  • the crystalline silica content of the physical component of the product may be greater than 1 wt % as measured according to one or more of the Traditional Methods.
  • the diatomite may be flux-calcined, and a cristobalite content of the physical component, as measured according to one or more of the Traditional Methods, may be greater than 1 wt % of the physical component and may be zero wt % of the physical component as measured according to the LH Method.
  • the crystalline silica content of the physical component of the product may be greater than 10 wt % as measured according to one or more of the Traditional Methods.
  • the diatomite may be flux-calcined, and a cristobalite content of the physical component, as measured according to one or more of Traditional Methods may be greater than 10 wt % of the physical component and may be zero wt % of the physical component as measured according to the LH Method.
  • the physical component of the product may have a detectable amount of the crystalline silica content as measured according to one or more of the Traditional Methods, and yet may not have a detectable amount of crystalline silica content as measured according to the LH Method.
  • the physical component may have a cristobalite content by weight as measured according to one or more of the Traditional Methods that is greater than as measured according to the LH Method, and the product may further comprise Silica Documentation that discloses the cristobalite content present in the physical component as measured according to the LH Method.
  • the crystalline silica content of the physical component by weight may be less than 0.3 wt % or less than 0.1 wt % when the cristobalite content of the physical component is measured according to the LH Method.
  • the crystalline silica content of the physical component may be less than 0.3 wt % or less than 0.1 wt % when a cristobalite content is measured according to the LH Method, and the physical component may have a Hegman value of 0.5 and 2.5.
  • a product comprises a physical component that includes diatomite, and Silica Documentation.
  • a crystalline silica content of the physical component by weight is greater as measured according to Traditional Methods than as measured according to a method that differentiates between opal-C and cristobalite.
  • a sum of an absolute value of a* for the product and an absolute value of b* for the product may be 2 to 5 for the product.
  • the Silica Documentation discloses the crystalline silica content present in the physical component as measured according to the method that differentiates between opal-C and cristobalite.
  • the method that differentiates between opal-C and cristobalite may be the LH Method.
  • the crystalline silica content as measured by the method that differentiates between opal-C and cristobalite may be less than 0.5 wt %, 0.3 wt % or 0.1 wt%.
  • the crystalline silica content as measured by Traditional Methods may be greater than 0.3 wt %, but may be less than 0.3 wt % when measured by the method which differentiates between opal-C and cristobalite.
  • Methods may be greater than 0.1 wt %, but may be less than 0.1 wt % when measured by the method which differentiates between opal-C an cristobalite.
  • the product comprises a physical component that includes diatomite.
  • the physical component may have a crystalline silica content that is (a) less than 10 wt % as measured by a method which distinguishes between opal-C and cristobalite and (b) greater than 10 wt % as measured according to one or more of the Traditional Methods.
  • a sum of an absolute value of a* for the physical component and an absolute value of b* for the physical component may be no more than 5 for the physical component.
  • the physical component may have no more than 1 wt % loss on ignition.
  • a product may comprise flux-calcined diatomite.
  • the product may have a total aluminum content in mineral form, expressed as the oxide, of 4 wt % to 6 wt %.
  • the product may further have 30 wt % to 45 wt % opal-C.
  • the sum of an absolute value of a* (for the product) and an absolute value of b* (for the product) may be 2 to 5 for the product.
  • a product in accordance with another aspect of the disclosure, may comprise flux-calcined diatomite.
  • the product may have a total aluminum content in mineral form, expressed as the oxide, of 2 wt % to 6 wt %.
  • the product may further have 30 wt % to 45 wt % opal-C.
  • the sum of an absolute value of a* (for the product) and an absolute value of b* (for the product) may be 2 to 5 for the product.
  • a product may comprise flux-calcined diatomite.
  • the product may have a total calcium content in mineral form, expressed as the oxide, of 0.2 wt % to 0.8 wt %.
  • the product may further have 30 wt % to 45 wt % opal-C.
  • the sum of an absolute value of a* (of the product) and an absolute value of b* (of the product) may be 2 to 5 for the product.
  • a product may comprise flux-calcined diatomite.
  • the product may have a total calcium plus aluminum content in mineral form, expressed as the oxides, of 4 wt % to 7 wt %.
  • the product may further have 30 wt % to 45 wt % opal-C.
  • the sum of an absolute value of a* (for the product) and an absolute value of b* (for the product) may be 2 to 5 for the product.
  • a product may comprise flux-calcined diatomite.
  • the product may have a total iron content in mineral form, expressed as the oxide, of 1 wt % to 2 wt %.
  • the product may further have 30 wt % to 45 wt % opal-C.
  • the sum of an absolute value of a* (for the product) and an absolute value of b* (for the product) may be 2 to 5 for the product.
  • a product in accordance with another aspect of the disclosure, may comprise flux-calcined diatomite.
  • the product may have an iron to calcium ratio in mineral form, expressed as the oxides, of 1: 1 to 10: 1.
  • the product may further have 30 wt % to 45 wt % opal-C.
  • the sum of an absolute value of a* (for the product) and an absolute value of b* (for the product) may be 2 to 5 for the product.
  • a product in accordance with another aspect of the disclosure, may comprise flux-calcined diatomite.
  • the product may have a total calcium plus aluminum content in mineral form, expressed as the oxides, of 3 wt % to 7 wt %.
  • the product may further have 30 wt % to 45 wt% opal-C.
  • a sum of an absolute value of a* for the product and an absolute value of b* for the product may be 2 to 5 for the product.
  • the physical component may be in powdered or in particulate form.
  • a second product that comprises any one of the above embodiments of a product.
  • a second product comprises a product that includes a physical component that contains diatomite.
  • the physical component may have less than 1 wt % crystalline silica, as determined by a method which distinguishes between opal-C and cristobalite.
  • An absolute value of a* for the physical component plus an absolute value of b* for the physical component may be no more than 5.
  • the physical component may have no more than 1 wt % loss on ignition.
  • the second product may be a coating, plastic film, or elastomer.
  • the second product may be a coating and may have a brightness L* value that is at least 90.
  • the second product may be a coating and the coating may be a wet coating that includes, or is, a waterborne latex.
  • the second product may be a coating and the coating may have a contrast ratio of 0.85 to 1.00.
  • the second product may be a coating and the coating may have an 85° sheen that is no more than 2.
  • the second product may be a coating and the coating may have a flatting efficiency that is at least 85%.
  • a method for preparing a product may include a physical component and Silica Documentation.
  • the method may comprise processing a selected diatomite ore with a fluxing additive to produce flux-calcined diatomite, and classifying the flux-calcined diatomite through either air classification, screening or centrifugal sifting to obtain the physical component.
  • the physical component may have a Hegman value of 0.5 to 7, wherein the sum of the absolute value of a* for the physical component and the absolute value of b* for the physical component may be in the range of 2 to 5 for the physical component.
  • the method may further comprise analyzing the physical component of the product for crystalline silica content using a test method that distinguishes between opal-C and cristobalite to determine cristobalite content.
  • the method further comprises preparing the Silica Documentation based on the results of the test method, wherein a crystalline silica content of the physical component by weight is greater as measured according to one or more Traditional Methods than as measured according to the test method, the Silica Documentation disclosing the crystalline silica content present in the physical component as measured according to the test method.
  • the test method is the LH Method.
  • the test method has a detection limit of 0 wt % to 0.5 wt % cristobalite.
  • the detection limit may be 0.5 wt % cristobalite; 0.3 wt % cristobalite; 0.1 wt % cristobalite; 0 wt % to 0.3 wt % cristobalite; 0 wt % to 0.1 wt % cristobalite; or less than 0.1 wt % cristobalite.
  • FIG. 1 is a graph of the X-ray Diffraction (XRD) pattern of the sample described as Example 1, with and without a cristobalite spike; and
  • FIG. 2 is an illustration of an exemplary product with exemplary Silica
  • products comprising a physical component that includes diatomite.
  • the diatomite may include flux-calcined diatomite.
  • a sum of an absolute value of a* for the physical component and an absolute value of b* for the physical component may be no more than 5 for the physical component.
  • the sum of the absolute value of a* for the physical component and the absolute value of b* for the physical component may be 2 to 5, 2 to 3.8 or 2.3 to 3.8 for the physical component.
  • the products have very low or non-detectable levels of crystalline silica which can be characterized by optical properties which are superior to the optical properties disclosed by Lenz et al. and which previously have not been found in the public domain.
  • Such products may also, optionally, comprise Silica
  • Documentation comprising data developed through use of a method which distinguishes opal-C from cristobalite and which has a detection limit as low as 0 wt % cristobalite to 0.5 wt % cristobalite, depending on the mineralogy of the DE.
  • the method which distinguishes opal-C from cristobalite may have a detection limit of 0.5 wt %, 0.3 wt %, 0.1 wt % or no more than 0.1 wt % cristobalite.
  • crystalline silica content of the physical component by weight may be greater as measured according to Traditional Methods than as measured according to the method that differentiates between opal-C and cristobalite.
  • the physical component may have no more than 1 wt %, no more than 0.5 wt%; no more than 0.3 wt %; or no more than 0.1 wt % crystalline silica as determined by a method which distinguishes between opal-C and cristobalite.
  • the physical component may have (a) less than 1 wt %, less than 0.5 wt%, less than 0.3 wt % or less than 0.1 wt % crystalline silica as determined by a method which distinguishes between opal-C and cristobalite or (b) zero wt % crystalline silica as determined by the method which distinguishes between opal-C and cristobalite.
  • the method may be the LH Method.
  • the physical component may have a crystalline silica content that is (a) less than 10 wt % as determined by a method which distinguishes between opal-C and cristobalite and (b) greater than 10 wt % as measured according to one or more Traditional Methods.
  • the physical component may have no more than 1 wt %, 0.5 wt %, 0.2 wt % or 0.1 wt % loss on ignition.
  • the physical component may have 30 wt % to 45 wt% opal-C and one or more of the following: (a) a total aluminum content in mineral form, expressed as the oxide, of 2 wt% to 6 wt% or 4 wt % to 6 wt %; (b) a total calcium content in mineral form, expressed as the oxide, of 0.2 wt % to 0.8 wt %; (c) a total calcium plus aluminum content in mineral form, expressed as the oxides, of 3 wt % to 7 wt % or 4 wt % to 7 wt %; (d) a total iron content in mineral form, expressed as the oxide, of 1 wt % to 2 wt %; or (e) an iron to calcium ratio in mineral form, expressed as the oxides, of 1 : 1 to 10: 1.
  • the physical component may have an L* value of at least 90, or 89 to 97.1, or of 89 to 95.
  • the physical component may have a d95 of no more than 50 ⁇ , no more than 30 ⁇ or no more than 27 ⁇ .
  • the physical component may have a CWD of no more than 0.42 g/ml, no more than 0.40 g/ml or no more than 0.32 g/ml.
  • the particle size distribution of fine powders can be determined using laser diffraction instrumentation. Particle size distribution of each sample described herein was determined using a Microtrac S3500 (three stationary lasers, two detectors, Mie scattering theory, ultrasonic dispersion, particle refractive index of 1.48, fluid refractive index of 1.333, irregular particle shape, transparent particles). Wet Sieve Analysis (+44 ⁇ ):
  • the wet sieve analysis provides an accurate measure of the mass of particles within a powder sample, coarser than, and finer than a specific point in the distribution, e.g. 44 ⁇ .
  • a powder sample of known mass is placed on a test sieve with square-shaped openings of the desired size (herein, 44 ⁇ ).
  • the sample is washed through the sieve using a water spray, and the residue (material coarser than the sieve opening size) is collected, dried, and re-weighed. This value is then compared with the original sample mass to give a measure of the percentage of particles larger than the sieve opening size.
  • the Gardner Coleman Oil Absorption (GCOA) test determines the absorptive capacity of powders.
  • the test gives an indication of unit mass of liquid absorbed per unit mass of solid powder.
  • Liquid of known specific gravity e.g., mineral oil
  • the powder is gently worked.
  • a visual end-point i.e. the powder "glistens”
  • the test is stopped and absorptive capacity calculated based on the mass of liquid used to saturate the known mass of powder.
  • the Hegman gauge and associated test method provide a measure of the degree of dispersion or fineness of grind of a pigment (or other functional additive powder) in a pigment- vehicle system. It is used to determine if a functional additive is of an appropriate size to embody the finished film (paint or plastic) with desired surface smoothness and other properties. Hegman values range from 0 (coarse particles) to 8 (extremely fine particles), and are related to the coarser end of the particle size distribution of the sampled powder. The Hegman gauge and test method are described in detail in American Society of Testing and Materials (ASTM) method D1210. The gauge itself is a polished steel bar into which a very shallow channel of decreasing depth is machined.
  • the channel is marked on its edge with gradations corresponding to Hegman values (0 to 8)).
  • the powder sample is dispersed within a liquid vehicle (paint, oil, etc.), and a small quantity of the suspension is poured across the deep end of the channel. A scraper is then used to draw the suspension toward the shallow end of the channel.
  • the channel of the gauge is then visually inspected in reflected light, and the point at which the suspension first shows a speckled pattern corresponds with the Hegman value.
  • One method for determining the bulk density of products comprising diatomite involves the use of a centrifuge. This method, described by Palm et al. in US Pat. No. 6,712,898, involves the suspension of a powder sample (1 to 2 g) in deionized water in a calibrated 15 ml centrifuge tube, followed by centrifugation under specific conditions (5 minutes at 2500 rpm on an International Equipment Company Centra® MP-4R centrifuge, equipped with a Model 221 swinging bucket rotor).
  • the volume of deionized water in which the powder sample is suspended is enough to make up a volume of approximately 10 ml in the centrifuge tube.
  • the mixture is shaken thoroughly so that there is no dry powder remaining in the centrifuge tube.
  • Palm et al. US Pat. No. 6,712,898
  • “[additional deionized water is added around the top of the centrifuge tube to rinse down any mixture adhering to the side of the tube from shaking.”
  • Post-centrifugation the volume level of the settled material is measured.
  • the sample weight of the powder sample divided by the measured volume of the settled material (post centrifugation) is the centrifuged wet density of the powder sample.
  • the test results in a measurement of bulk density called “centrifuged wet density” (CWD).
  • CWD centrifuged wet density
  • the free moisture content of spent cake, DE sample, and other materials can be determined by measuring the sample mass before and after drying at low temperature (105 °C) for an exposure time of 24 hours. Relatively low temperature is needed to prevent volatilization of organic content.
  • the loss on ignition (LOI) test provides an estimate of the volatile content (by mass) of dried diatomite or other materials. The test is performed by measuring the dried sample mass before and after heating at 1000 °C for at least one hour. This test gives an approximate measure of the water of hydration content of a DE sample or a sample containing DE.
  • the bulk chemistry or elemental analysis of a material can be determined using wavelength-dispersive x-ray fluorescence spectroscopy.
  • a Bruker S4 Explorer WDXRF spectrometer or a Bruker S8 Tiger WDXRF were used to determine the bulk chemistry of samples described herein.
  • the optical properties of products may be characterized using the color space defined by the Commission Internationale de I'Eclairage (CIE), as the L*a*b* color space.
  • the "L*” coordinate is a measure of reflected light intensity (0 to 100).
  • the "a*" coordinate is the degree of redness (positive value) or greenness (negative value).
  • the "b*” coordinate is the degree of yellowness (positive value) or blueness (negative value).
  • the CIE previously developed a chromaticity coordinate system (Yxy) that is also still used in defining the brightness and chromaticity of products.
  • the "Y" value is the luminance or brightness factor, where a value of 100 is equivalent to the brightest white.
  • a Konica Minolta® Chroma-meter CR-400 was used to measure the optical properties (L*a*b* and Y) of samples described herein.
  • Paint testing involves the incorporation of the specific functional additive within a paint formulation, preparation of draw-downs, and determination of specific properties of the dried paint film in comparison with controls.
  • a waterborne latex paint formulation with a pigment volume concentration (PVC) of 51 and about 35 vol.% total solids was used; however, formulations for other types of paints will be known to those skilled in the art.
  • PVC values are often used to generally identify the type of paint that will be produced in terms of the resultant gloss and sheen
  • DE-based fillers are often incorporated in coatings with lower sheen values such as flat, velvet, or eggshell paints (all with 85° sheen values less than about 35), but may be utilized in higher sheen paints such as semi-gloss or gloss (typically with 60° gloss values greater than about 35).
  • the paint formulation utilized herein has a 85° of sheen value of about 11.2 and decreases to different values when DE is incorporated depending on the characteristics of the DE. It is possible to create higher sheen paints, with 85° sheen values no more than 35, using a finer DE sample or altering the formulation.
  • Sample paints were cast at 76.2 ⁇ (3 mil) wet thickness onto a Leneta Form 3B chart (Leneta Company, USA) using a bird applicator. The films were dried under ambient conditions for three days prior to measurement.
  • Optical properties of interest for the finished paint include brightness, color, contrast ratio, gloss/sheen, and color match.
  • the contrast ratio is a measure of the opacity of a paint or how well a paint "hides" the underlying film or substrate. High contrast ratio is often desirable to reduce the number of coatings required to complete a paint job to the customer's satisfaction. Contrast ratio is calculated by dividing the Y value measured on the black area of the Leneta chart by the Y value measured white area:
  • Gloss or sheen of a surface refers to the light reflectivity of that surface at specific incident angles (20°, 60°, 85°). Typically, when the 60° gloss value is less than 20, only the 85° sheen is reported. Here, the gloss and sheen values were measured by a gloss meter (micro-TRI-gloss 4520, Byk-Gardner, USA).
  • Flatting efficiency is based on a number of factors including particle shape, size, and distribution. Differences in GCOA and bulk density also have an impact, as does film thickness. Herein, all films were cast at equal wet film thickness. Flatting efficiency is calculated as:
  • the difference in overall color ( ⁇ *) between a paint sample and a reference sample or a control sample can be calculated by measuring the difference in L*, a*, and b* values between the sample and a "reference" or control sample.
  • the difference in L*, a*, and b* can be used to calculate ⁇ * by:
  • PSD particle size distribution
  • SWeFFcs Size- weighted Fine Fraction - crystalline silica
  • Tables 4 and 5 show the crystalline silica contents of natural and flux- calcined diatomite products which are commonly used as functional additives, as reported in the crystalline silica data section of SDSs of EP Minerals, Imerys Filtration Minerals, Ceca, Dicalite Corp., and Showa Chemical.
  • EP Minerals, Imerys Filtration Minerals, Ceca, Dicalite Corp. and Showa Chemicals are manufacturers of natural and flux-calcined diatomite products.
  • "Celatom” is a trademark of EP Minerals.
  • Celite "Kenite”, and “Diafil” are trademarks of Imerys Filtration Minerals
  • Clarcel is a trademark of Ceca
  • Radiolite is a trademark of Showa Chemicals
  • Dicalite is a trademark of Dicalite Minerals Corp.
  • the natural products which are diatomite products that are processed thermally at temperatures sufficient to dry the material but low enough to prevent significant dehydration of the opal-A component of the diatomite and also prevent significant agglomeration of the diatomite, are available with qualities amenable for use as functional additives. Due to the lower processing temperatures, natural diatomite products have generally been reported as containing low or no measurable levels of crystalline silica, although some products contain up to about 4 wt % crystalline silica, generally in the form of quartz.
  • a "Traditional Method” means a method that uses XRD analysis to measure and quantify (using such measurement) crystalline silica phases in a diatomite product without regard to whether opaline phases (opal-C and/or opal-CT) or cristobalite are actually present, and assuming that said opaline phases are actually cristobalite.
  • opaline phases opal-C and/or opal-CT
  • cristobalite quartz, or tridymite can be compared to its respective standard (for example NIST SRM 1878b for quartz) for quantification of the content, or be quantified through the use of an internal standard (such as corundum) and applicable relative intensity ratios.
  • NIST SRM 1878b for quartz for quantification of the content
  • an internal standard such as corundum
  • Method 7500 is one example of a Traditional Method for measuring respirable crystalline silica in dust samples, including dusts comprising diatomaceous
  • Method 7500 references a number of possible interfering phases, including micas, feldspars, and clays, but no mention is made of opal-C or opal-CT, and there is nothing in the test method providing for the quantification of these phases.
  • the quantification of the crystalline silica phases in diatomite product(s) includes the opaline phase (opal-C and opal-CT) content as well. More specifically, such Traditional Methods treat the opaline phases as if they were cristobalite and, as such, quantify the combination of cristobalite plus opaline phases as the "cristobalite content" of a product; this results in an overstatement of the cristobalite content of the product (and an overstatement of the crystalline silica content of the product).
  • opaline phase opal-C and opal-CT
  • reporting methods indicate which commercial products contain, based on the Traditional Methods, measurable amounts of quartz or cristobalite, the reporting methods do not provide a clear indication of the average or typical crystalline silica contents of these products. As a result, the inventors have included actual measurements of selected products in Table 6 (measured using the Traditional and LH Methods).
  • one relatively simple way to confirm the absence of cristobalite within a sample is to spike the sample (add a known amount of) with cristobalite standard reference material (i.e. National Institute of Standards and Technology (NIST) Standard Reference Material 1879 A), run XRD analysis on the spiked sample and then compare the original un-spiked sample diffraction pattern with the spiked sample pattern. If the spiked sample diffraction pattern simply increases the intensity of the primary and secondary peaks but does not show a position shift or show additional peaks, then the original sample most likely contains cristobalite.
  • cristobalite standard reference material i.e. National Institute of Standards and Technology (NIST) Standard Reference Material 1879 A
  • a (representative) second portion of the sample is obtained and bulk powder XRD is performed on the second portion.
  • the second portion is milled prior to XRD.
  • the resulting (first) diffraction pattern is analyzed for the presence or absence of opal-C (opal-C and/or opal-CT) and cristobalite.
  • the resulting (first) diffraction pattern may also be analyzed for the presence or absence of other crystalline silica phases (for example, quartz and tridymite) within the (representative) second portion of the sample.
  • the opal-C (opal-C and/or opal-CT) diffraction pattern differs from that of a-cristobalite in the following ways: the primary peak (22°) and the secondary peak (36°) are at higher d-spacing (lower 2 ⁇ angle), there is a broader primary peak for opal-C (opal-C and/or opal-CT) as measured using the "Full Width at Half Maximum" (FWHM) statistic, opal-C (opal-C and/or opal-CT) has poorly-defined peaks at 31.50 and 28.49 2 ⁇ , and a much more significant amorphous background.
  • FWHM Full Width at Half Maximum
  • a second XRD analysis is performed to determine whether opal-C (opal-C and/or opal-CT) and/or cristobalite is present. This time the analysis is performed on, preferably, another representative portion of the sample spiked with cristobalite standard reference material (NIST 1879a). For example, a (representative) third portion of the sample is obtained and then spiked with cristobalite standard reference material (NIST 1879a) and XRD is performed on the third portion.
  • the resulting (second) diffraction pattern from the XRD on the third portion is analyzed.
  • the third portion is milled prior to XRD.
  • the original sample for example, the representative second portion of
  • the representative second portion of comprises opal-C (opal-C and/or opal-CT)
  • the cristobalite spike significantly modifies the diffraction pattern (from that of the second portion) with additional peaks identifiable at 22.02 and 36.17 2 ⁇ , along with more prominent peaks at 31.50 and 28.49 2 ⁇ seen in the (second) diffraction pattern of the third portion.
  • the original sample (more specifically, the second portion of) comprises cristobalite
  • addition of the cristobalite spike (to the third portion) only results in increased peak intensity and no other significant change from the (first) diffraction pattern of the second portion (as seen in the (second) diffraction pattern of the third portion).
  • Quantifying the opal-C (opal-C and/or opal-CT) content of a diatomite sample can be complicated as its diffraction pattern is a combination of broad peaks and amorphous background, and diatomite products often contain other x-ray amorphous phases in addition to opal.
  • an estimate of the quantity is obtained by treating the opal-C (opal-C and/or opal-CT) peaks (collectively, if both phases are present) of the first diffraction pattern as if they are cristobalite and quantifying against cristobalite standards such as NIST 1879a.
  • This method of quantification of opal-C (opal-C and/or opal-CT) which Lenz et al. call the XRD Method, will usually underestimate the opal-C (opal-C and/or opal-CT) content but is effective for a number of purposes, such as manufacturing quality control.
  • this XRD Method is part of the umbrella LH Method.
  • a measure may be obtained by heating a representative portion of the sample (for example, a fourth portion) at very high temperature (e.g., 1050 C) for an extended period (for example 24 to 48 hours) until that heated portion is fully dehydrated. This completely dehydrates opaline phases and forms cristobalite (reduces amorphous background component).
  • the fourth portion is milled prior to XRD. As long as additional flux is not added prior to heating the fourth portion, and the temperature kept below 1400 °C, any quartz present in the fourth portion will not be converted to cristobalite.
  • each of quartz or tridymite may be compared to its respective standard (for example, NIST SRM 1878b for quartz) for quantification of the content, or be quantified through the use of an internal standard (such as corundum) and applicable relative intensity ratios.
  • the cristobalite seen in the (first) diffraction pattern of the second portion of the sample may be compared to its respective standard (for example NIST 1879a) for quantification of the content, or be quantified through the use of an internal standard (such as corundum) and applicable relative intensity ratios.
  • its respective standard for example NIST 1879a
  • an internal standard such as corundum
  • the opal-C (or opal-CT) and cristobalite are quantified as one phase and reported as cristobalite.
  • the quantity of cristobalite thus reported will be higher than the actual quantity in the sample. Because the sample is a representative sample of the product, the total weight percentage of the crystalline silica content in the sample is considered to accurately represent the total weight percentage of the crystalline silica content in the product from which the sample was taken.
  • Table 6 shows the Hegman, L*, a*, b*, and crystalline silica contents of several commercial diatomite products comprising physical components already in the public domain, as characterized in EP Minerals Research and Development laboratories.
  • the data in this table are consistent with the data of Tables 4 and 5, and show that flux- calcined diatomite functional additives characterized using either traditional XRD techniques for crystalline silica content or the LH Method as disclosed in Lenz, et al., all contain levels of crystalline silica above the detection limit, with the lowest percentage content of crystalline silica at a level of 40 wt % and the highest above 80 wt %.
  • Table 6 also shows that some natural diatomite products do not contain measurable levels of crystalline silica.
  • Celabrite of crystalline silica in diatomite product samples is 0 wt % to 0.5 wt %, depending on the mineralogy of the DE.
  • Table 3 contains data from Lenz et al. concerning flux-calcined samples from diatomite ores with differing bulk chemistry, flux-calcined under the exact same process conditions (7 wt% soda ash, flux-calcined at 927 °C for 40 minutes).
  • Opal-C quantification is based on XRD procedure as described in the LH Method Lenz et al.
  • the detection limit of the LH Method for the determination of crystalline silica in diatomite product samples is 0 wt % to 0.5 wt %, depending on the mineralogy of the DE.
  • Example 1 was prepared from a composite sample of crude DE ore using the following steps: drying at 120 °C for 24 hours; crushing (jaw crusher) to minus 1.25 cm; dry-sieving at 80 mesh (180 ⁇ ), and collecting the minus 80 mesh portion; blending with soda ash using a paint shaker; calcination in an electric muffle furnace in ceramic dishes; and sieving at 70 mesh (212 ⁇ ) with overs brushed through the sieve.
  • Example 2 was prepared from a drill-hole composite DE sample using the following steps: drying at 177 °C for 24 hours; crushing (jaw crusher) to minus 1.0 cm; milling (Hosokawa Mikro UMP hammer mill) and classifying (Sturtevant Separator) with coarse fraction discarded; blending with soda ash using a paint shaker; calcination in a gas-fired muffle furnace; roll-crushing; wet-sieving at 325 mesh (44 ⁇ ) with the minus 325 mesh fraction collected, dried, and evaluated as a functional additive.
  • Example 3 was prepared from a crude DE ore sample using the same steps as with Example 2, with the exception of the final wet-sieving step.
  • Example 4 was prepared from a composite sample of crude DE ore in a similar fashion to Example 3.
  • Example 5 was prepared from a crude DE ore sample as with Example 3, with the additional step of a post-calcination classification using a Comex ACX-50 classifier.
  • FIG. 1 is the XRD pattern of the sample of Example 1 (2a) of Table 7 overlaying the same sample with a 10 wt% cristobalite spike (2b).
  • the standard stick pattern of a-cristobalite (3) is super-imposed in FIG. 1. While the cristobalite primary peak (lb) in this case still overlaps the opal-C primary peak (la), the addition of the spike shows a significant change in the pattern and not just an increase in intensity. This presents solid proof that the identification of the opal-C phase is correct when the LH Method is used.
  • Silica Documentation was prepared for the sample of Example 1, both using the Traditional Method (incorrectly identifying opal-C as cristobalite) and the LH Method.
  • Table 9 is the SDS information for sales within the United States prepared using data generated via the Traditional Method for determining the cristobalite content in flux- calcined diatomite products.
  • Table 10 is the corrected SDS information using data generated with the LH Method. Significant changes were made in sections 2 (hazards), 3 (composition), 8 (exposure controls), 11 (toxicological information), and 15 (regulatory information), in comparison with the SDS information shown in Table 9.
  • Table 9 SDS Information for Example 1 with Data based on Traditional Methods
  • INHALATION Remove to fresh air. Blow nose to evacuate dust.
  • Dust may cause abrasive irritation to eyes. Prolonged skin contact
  • Dust may cause nose, throat and upper symptoms/effects, respiratory tract irritation. Prolonged inhalation of respirable dust acute and delayed containing silica may cause a progressive lung disease, silicosis and lung cancer. See Section 11 for additional information.
  • the material is not combustible.
  • Respirators fitted with filters certified to standard 42CFR84 under series N95 should be worn when dust is present. If the dust concentration is less than ten (10) times the Permissible Exposure Limit (PEL) use a quarter or half-mask respirator with a N95 dust filter or a single use dust mask rated N95. If dust concentration is greater than ten (10) times and less than fifty
  • PROTECTION replaceable N95 filters is recommended. If dust concentration is greater than fifty (50) and less than two hundred (200) times the PEL use a power air-purifying (positive pressure) respirator with a replaceable N95 filter. If dust concentration is greater than two hundred (200) times the PEL use a type C, supplied air respirator (continuous flow, positive pressure), with full face piece, hood or helmet.
  • Acute inhalation can cause dryness of the nasal passage and lung congestion, coughing and general throat irritation.
  • Acute inhalation of high concentrations of respirable crystalline silica may cause acute silicosis.
  • This product contains crystalline silica. Respirable crystalline silica may cause lung cancer and lung disease
  • silicosis if inhaled for prolonged periods. Symptoms of silicosis include wheezing, cough and shortness of breath.
  • Flux-calcined diatomaceous earth (Kieselguhr) is composed of amorphous and crystalline silica. Respirable crystalline silica (cristobalite) is classified by IARC and NTP as a
  • Crystalline silica is only known to cause cancer when inhaled in a respirable form. It is not known to cause cancer by any other route of exposure.
  • Respirable crystalline silica (cristobalite) is classified as a
  • Respirable crystalline silica (cristobalite) is classified as a
  • Diatomaceous earth products have shown some efficacy as a
  • DISPOSAL typically solid waste disposal common to landfill type operations.
  • Diatomaceous Earth is not classified as a hazardous substance
  • INHALATION Remove to fresh air. Blow nose to evacuate dust.
  • Dust may cause abrasive irritation to eyes. Prolonged skin
  • Dust may cause nose, throat and symptoms/effects, acute
  • the material is not combustible.
  • Respirators fitted with filters certified to standard 42CFR84 under series N95 should be worn when dust is present. If the dust concentration is less than ten (10) times the Permissible Exposure Limit (PEL) use a quarter or half-mask respirator
  • RESPIRATORY with a N95 dust filter or a single use dust mask rated N95. If PROTECTION dust concentration is greater than ten (10) times and less than fifty (50) times the PEL, a full-face piece respirator fitted with replaceable N95 filters is recommended. Selection and use of respiratory equipment must be in accordance with OSHA 1910.134 and good industrial hygiene practice.
  • REACTIVITY Material is not reactive.
  • Acute inhalation can cause dryness of the nasal passage and
  • Diatomaceous earth without crystalline silica is not classified
  • Diatomaceous earth without crystalline silica is not
  • DISPOSAL typically solid waste disposal common to landfill type operations.
  • Diatomaceous Earth is not classified as a hazardous substance under regulations of the Comprehensive Environmental
  • FIG. 2 illustrates an exemplary embodiment of a product 4.
  • the product 4 includes a physical component 6 (of the product 4) and a data component 9.
  • the data component 9 includes Silica Documentation 8.
  • the Silica Documentation 8 includes a product label 8a, a bar code 8b and an SDS 8c. This is not to imply that all three of these types of Silica Documentation 8 must be associated with a given product 4.
  • FIG. 2 is for exemplary purposes only.
  • the Silica Documentation 8 may include one or more of a regulatory support document(s), hazard disclosure(s), Safety Data Sheet(s), label(s), product label(s), product bar code(s), certificates of analysis or other electronic or printed forms of data which document or disclose crystalline silica content, or the absence of crystalline silica in the content, of the product 4.
  • a regulatory support document(s) hazard disclosure(s), Safety Data Sheet(s), label(s), product label(s), product bar code(s), certificates of analysis or other electronic or printed forms of data which document or disclose crystalline silica content, or the absence of crystalline silica in the content, of the product 4.
  • the Silica Documentation 8 may include one or more of a regulatory support document(s), hazard disclosure(s), Safety Data Sheet(s), label(s), product label(s), product bar code(s), certificates of analysis or other electronic or printed forms of data which document or disclose crystalline silica content, or the absence of crystalline silica in the content, of the product 4.
  • Documentation 8 (associated with the product 4) discloses crystalline silica content present (or the absence of crystalline silica) in the physical component 6 as determined, measured or quantified by the LH Method. As noted previously, the absence of crystalline silica (for example, cristobalite, quartz, tridymite) is disclosed either by an explicit statement or an absence of crystalline silica from the product contents identified by the Silica Documentation 8.
  • Table 11 contains data related to samples collected from a production-scale trial conducted in December 2017 in EP Minerals' Lovelock, Nevada facility. Both samples (Example 8 and Example 9) were flux-calcined with low soda ash addition in a rotary kiln at relatively low temperature, then classified using an air classification system to remove a coarse fraction from the final product.
  • Example 8 is a sample of a functional additive with a very fine particle size distribution suitable for use as an anti- block in plastic film.
  • Example 9 is a sample classified for use as a flatting agent in paint formulations.
  • Opal-C quantification is based on XRD procedure as described in the LH Method Lenz et al.
  • the detection limit of the LH Method for the determination of crystalline silica in diatomite product samples is 0 wt % to 0.5 wt %, depending on the mineralogy of the DE.
  • the teachings of this disclosure include novel products comprising flux- calcined diatomite and novel Silica Documentation.
  • Such products properly characterized by Silica Documentation based on the LH Method, provide benefits in the analysis of potential product hazards, appropriate incentives for the producers of products that include diatomite to develop and introduce new products comprising reduced levels of crystalline silica and improved information regarding the potential exposures of both workers and consumers to crystalline silica, and respirable crystalline silica.
  • the product includes a physical component.
  • the product may further include Silica Documentation.
  • the method may comprise processing a selected diatomite ore with a fluxing additive to produce flux-calcined diatomite, and classifying the flux-calcined diatomite through either air classification, screening or centrifugal sifting to obtain the physical component, the physical component having a Hegman value of 0.5 to 7, wherein the sum of the absolute value of a* and the absolute value of b* is in the range of 2 to 5 for the physical component.
  • the fluxing additive may include one or more of the following fluxing additives or mixtures thereof: sodium carbonate (soda ash), sodium chloride (salt), sodium sesquicarbonate, sodium borate, sodium aluminate, or other sodium-based fluxes.
  • the method may further comprise analyzing the physical component of the product for crystalline silica content using a test method that distinguishes between opal-C and cristobalite to determine cristobalite content.
  • the method may further comprise preparing the Silica Documentation based on the results of the test method, wherein a crystalline silica content of the physical component by weight is greater as measured according to one or more Traditional Methods than as measured according to the test method, the Silica Documentation disclosing the crystalline silica content present in the physical component as measured according to the test method.
  • the test method may be the LH Method.
  • the test method may have a detection limit of 0 wt % to 0.5 wt % cristobalite.
  • the test method may have a detection limit of 0.5 wt % cristobalite; 0.3 wt % cristobalite; 0.1 wt % cristobalite; less than 0.1 wt % cristobalite; or 0 wt % to 0.3 wt % cristobalite.

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Abstract

L'invention concerne des produits qui comportent un composant physique et une documentation silice, et des procédés de préparation de tels produits. Le composant physique comprend de la diatomite calcinée par flux. Une valeur absolue de a * pour le composant physique plus une valeur absolue de b* pour le composant physique peut ne pas être supérieure à 5. La teneur en poids de silice cristalline dans le composant physique est plus grande si elle est mesurée selon des procédés classiques plutôt que selon un procédé qui différencie l'opale C et la cristobalite. La documentation silice concerne la teneur en silice cristalline présente dans le composant physique, telle que mesurée selon le procédé qui différencie l'opale C et la cristobalite.
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US12070732B2 (en) 2018-12-20 2024-08-27 U.S. Silica Company Highly effective functional additive products

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US12070732B2 (en) 2018-12-20 2024-08-27 U.S. Silica Company Highly effective functional additive products
CN115362017A (zh) * 2020-01-30 2022-11-18 Ep矿产有限公司 制备直出硅藻土功能填料产品的方法

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