TALC

Talc is a layered, hydrous magnesium silicate mineral. It has a soft, soapy feel and typically a smooth texture and is known for its insulation, heat resistance, chemical stability, oil absorption and strong covering quality. Talc (Mg3Si4O10(OH)2) has a theoretical chemical composition of MgO at 31.7 percent, SiO2 at 63.5 percent and H2O at 4.8 percent. However, talc’s chemical and mineralogical composition can vary depending on its geological history/parent rock association. These mineral associations are usually chlorite, quartz and carbonates (magnesite, calcite and dolomite), in varying levels. Two key elemental substitutions can occur in the talc crystal structure — iron for magnesium and fluorine for hydroxyl. These compositional differences may limit or enhance the usage of talc in specific market niches. The United States remains self-sufficient in most grades of talc. Talc deposits are categorized under four origintypes occurring as secondary and/or tertiary alterations of pre-existing rocks: (1) ultramafic, (2) mafic, (3) metasedimentary and (4) metamorphic. Type 1 deposits, while the most abundant, are generally of lower grade and are second to Type 3 deposits based on utilization-commercialization. Type 4 deposits, while historically a dominant source, have diminished substantially in their usage over the years due to elevated amphibole content. Type 2 deposits are the least pure and utilized of all the origin-types. Another representation of the four talc origin categories noted above can be ultramafic/mafic, metasedimentarycarbonate, metasedimentary-silicoaluminous and metamorphic. Historically, product groupings such as industrial, cosmetic and pharmaceutical had inferred or denoted purity. Presently, these groupings are no longer considered strict purity guidelines. Talc products can be categorized as chloritic-talc, carbonate-talc or tremolitic-talc. The hyphenated statement denotes the second most dominant mineral phase up to 50 percent. Pyrophyllite is a layered hydrous aluminum silicate mineral. Pyrophyllite has similar physical properties as talc while elemental substitutions are minimal compared to talc. Pyrophyllite (Al2Si4O10(OH)2) has a theoretical chemical composition of Al2O3 at 28.3 percent, SiO2 at 66.7 percent and H2O at 5 percent. Typical accessory minerals are quartz, kaolin, diaspore, boehmite, sericite and chlorite, in addition to iron-containing impurities of hematite, limonite/ goethite and pyrite. Grades are differentiated by particle size, moisture content, fired color and purity, as measured by fineness and screen residue. Pyrophyllite deposits are generally classified as hydrothermal or metamorphic. Subtypes are as follows: (1) hydrothermal in metasomatites continental and island-arc volcanic zones, platforms, folded systems, (2) hydrothermal in metasomatites in wall-rock quartz veins-granitoids and metamorphosed clastic suites, (3) metamorphosed metasomatites in submarine volcanic zones enclosing sulfide ores, (4) stratiform metamorphosed clastic clay suites with pyroclastic material and coal seams, and (5) clays formed by weathering. Pyrophyllite has high dielectric strength, low electrical conductivity, reasonably high thermal stability, and chemical inertness that allows for primary usages in refractory and ceramic applications. Production and consumption In 2022, the primary producer of pyrophyllite in the United States with worldwide distribution was Vanderbilt Minerals LLC – Standard Mineral Division (owned by R.T. Vanderbilt) in North Carolina. The parent company celebrated its 100-year anniversary in 2016. The division owns more than 1,500 acres of land that have reserves of more than 100 years. Pyrophyllite ore is mined in several openpit mines and is crushed, dry-ground and air-classified at the division’s mill in Robbins. The processed pyrophyllite ore is sold under the trade name PYRAX. Piedmont Minerals, also in North Carolina, supplies product but mainly for inhouse usage for their parent company, RESCO. While the company’s actual domestic production figures were not disclosed by the U.S. Geological Survey (USGS), domestic 2022 pyrophyllite production was estimated to have increased from 2021 as the United States and world work through post-pandemic economics. Consumption was dominant refractory, ceramics and paint. Critical attributes in refractory applications are iron and quartz content, while a critical attribute in ceramics is whiteness before and after firing. Additional industrial usages are in paint, chemical carriers in agriculture, and filler in industrial coatings, sealants, polymers and caulks. In 2022, three talc companies operated five talc mines and production facilities located in three states, accounting for 99 percent of domestic production. Domestic production is via openpit mining. Montana continues to be the leading state for production, followed by Texas and Vermont. Magris Talc has mines and processing facilities in Montana, Vermont and Canada. Minerals Technologies Inc. through its Barretts Minerals, a subsidiary of Specialty Minerals Inc., has mining and processing facilities in Montana and processing in Texas. CIMBAR Performance Minerals has processing facilities for imported talc in Indiana, Ohio and Texas in addition to facilities in China and Pakistan. Natural Minerals (formerly American Talc Co.) had mining and processing facilities in Texas. IMI FABI has processing facilities in West Virginia, in addition to, mines and operations in Brazil, Italy, Australia, Pakistan and China. For 2022, estimated talc production continued to rebound from post-pandemic economics and is estimated at 580 kt, an increase of about 1 percent from 2021. Total talc sold by the producers, including domestic sales and exports, was estimated at 560 kt, an increase of about 1 percent from 2021 levels of 556 kt, but overall, the last two years have seen a substantial increase from 2020 levels. The total talc sold was valued at $180 million. For 2022, estimated apparent consumption of talc was at 690 kt, an increase of about 15 percent from 2021 levels. The estimated 2022 average price for a processed metric ton of product decreased slightly from $321 to $320. The distribution of talc produced and sold domestically was as follows: ceramics including catalytic converter (18 percent), paint (16 percent), paper (23 percent), plastics (18 percent), rubber (4 percent), roofing (2 percent), and the remainder of 19 percent included a variety of applications of cosmetics, pharmaceuticals, refractories, agricultural products, animal-feed, sealant, sculpturing, food and polishing. Exports/imports The 2022 estimated talc exports were 200 kt, a decrease of about 14 percent from the 2021 actual exports of 232 kt. The 2022 estimated talc imports were 330 kt, an increase of 18 percent from 2021 at 278 kt and a significant rebound from 2020 pandemic levels. From USGS reporting, imported talc was sourced from Canada, China and Pakistan, with imports from these countries increasing and accounting for approximately half of the import tonnage. The USGS reported that crude ore from Afghanistan was being milled and exported through Pakistan to other countries. Imported talc was used in various applications of cosmetics, paints and plastics with remaining usage for ceramics, paper, roofing and rubber. World mine talc production included dominant sources from the United States, Brazil, Finland, Canada, China, France, India, Italy, Japan and Korea. Employment Talc sector employment continued its decline since 2007 with another substantial decline from 2020 to 2022 at approximately 205 percent, from 187 to 150 employment. Pyrophyllite mine employment ranged from 25 to 31 from 2012 to 2022. Uses, new applications, processing technology and future trends Talc producers must continue to provide a functional and high-performance mineral additive that can increase the value of their products to the end-use customer. In specific cases, unique properties of the talc product can be achieved by employing proprietary coatings or processing by delamination to increase aspect ratio or to increase the overall purity by beneficiation. Silane- or siloxane-based and directed surface treatments are commonplace. Nanotalc products (10 to 100 nanometers in one dimension) continue to be researched and marketed for uses in various applications. Talc usage covers a multitude of product categories: plastics, cosmetics, flooring, health care, catalytic converters, animal feed, caulks, sealants, gaskets, belts, hoses, specialty antiblocking/antihazing in plastic films, automotive-body putty, asphalt shingles, joint compounds, pharmaceuticals, ceramics and dimension stone. In ceramic applications of dinnerware, sanitaryware and hobby ceramics, talc provides low shrinkage as well as high brightness upon firing at various temperatures. In other applications, highquality calcined-talc blends can be tailored to each customer’s specifications to impart a controlled shrinkage and reduce firing time. The reduced firing time aids in processing and energy costs for the customer. Another specialty usage for which talc demand remains high is fired-cordierite bodies used for catalytic converters for vehicles. In dimension stone applications, talc is used for countertops, sinks, mantels, fireplace surrounds, pavers and tile brick. In paints, talc is an economic extender and filler while providing brightness and durability to paint coatings. In rubber applications, talc provides reinforcement as well as ultraviolet-radiation resistance and can be used as a processing aid for good extrusion rates, impermeability and improved surface finish. However, more paints are shifting to water-based matrices from oil-based matrices to reduce organic volatiles; talc, being hydrophobic in nature, loses opportunities in these market-product shifts. The plastics market continues to offer some potential growth opportunities, especially in polypropylene. It is projected that talc usage for lightweight and recyclable products will increase for the automotive market with compacted and submicron talc products to enable manufacture of highperformance end-use products. Talc continues to be used in the papermaking process, especially as a pitch control agent while it faces competition in the paper filler and niche paper coating sectors from precipitated and ground calcium carbonates.

TALC

Authored by:
G. P. Tomaino

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From sessions to strategy: Revealing long-term and emerging innovation trends in data analytics, intelligent systems and automation

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To view the past issues of the UCA magazine you must be a member of SME/UCA.

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