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By J. Budac, R. Krentz, P. Cordingley, G. Freeman, M. E. Chalkley, H. Scheie

Pressure hydrometallurgical unit operations have been in commercial use at the Fort Saskatchewan refinery of Sherritt International Corporation for fifty years. This paper traces the history of Sherritt from its origins in northern Manitoba, and the development of the first hydrometallurgical nickel-cobalt refinery in 1954, utilizing pressure hydrometallurgy, to the modern day refinery. Sherritt's involvement with pressure hydrometallurgy during the past 50 years has included the operation of the refinery, the development and licensing of technology, incorporating pressure hydrometallurgical unit operations, to more than 30 companies worldwide, the joint venture at Moa, Cuba involving both leaching and precipitation at elevated temperature and pressure, and the production of specialty metal powders. Developments in each of these areas are reviewed.

Jan 1, 2004

By J. W. Stevenson

At this 5th U.S. Mine Ventilation Symposium I would like to focus your attention on safety and the contribution of the ventilation engineer over the past 50 years. This conference affords us the opportunity to express, to listen, and to learn. As ventilation engineers it is indeed an exciting time--a time that not only stimulates our imagination but also pin points our aims in our quest to obtain zero fatalities by the year 2000, the goal expressed by William J. Tattersall, Assistant Secretary of Labor, Mine Safety and Health Administration. In the past, coal mine ventilation has often been unfortunately synonymous with explosions and resulting fires. Those not familiar with us do not recognize the painful evolution of the coal mining industry and particularly the evolution of mine ventilation. To put my presentation into perspective, I recently reviewed a U.S. Bureau of Mines Bulletin No. 586 - "Historical Summary of Coal-Mine Explosions in the United States 1810 - 1958 prepared by H. B. Humphrey Mining Health and Safety Engineer. This bulletin was published in 1960. Mr. Humphrey stated "In 1946, factors contributing to the explosions occurring from 1941 to 1945 were: (1) The rapid increase in the use of electrical equipment at face regions where gas and dust are most likely to be found; (2) the increased demand for coal with the desire to obtain maximum tonnage per machine at minimum cost, which in many mines has resulted in neglect of even rudimentary precautionary measures; (3) multiple-shift operation without provision of time for adequate maintenance of equipment, effective rock dusting, and testing for gas; (4) decrease in supervision owing to demands on supervisors for maximum tonnage and loss of competent supervisors to other employment; (5) lack of effective supervision, owing to numerous new conditions, some of them war-connected; (6) inability to obtain adequate equipment repair and replacement parts; (7) shortage of labor and inadequate training of coal-mine workers; and (8) failure of both miners and mining officials to show regard for safety in changing from hand-loading to mechanized methods". Most of the eight factors listed by Mr. Humphrey continue to affect our work lives as mining engineers. The increased demand for coal with the desire to obtain maximum tonnage per machine at minimum cost has never changed. The local and regionalized coal industry of the 40's is today competing against the world coal market. Our mines work or shut down based on cost. This has always been the case. During the five year time-frame Mr. Humphrey was documenting, 345 miners were killed in major explosions. A major explosion was one in which five or more miners were killed in a single accident. In addition, 105 more miners were killed in minor explosions for a total of 450. What a wanton waste of life. What fears, anxieties, miseries, and sufferings were created by these accidents. However, we must remember and keep in mind that the coal mining company officials, engineers, and foremen, the governmental agencies- federal, state, and local - were using the technical tools and knowledge available to operate the mines as safely as they could. Obviously mine ventilation engineering technology was woefully inadequate.

Jan 1, 1991

By D. Purdie

"This paper aims to remind researchers, designers, operators, and managers about the benefits of seeding in the design of precipitation stages in their flowsheet. Including a high density solids (HDS™) process encourages the precipitating solids to form on the surface of existing precipitated particles. This paper discusses the application of the HDS technology at Kennecott Smelter, where the authors have witnessed significant improvements in settling and filtration rates. The authors have also applied this technology at various smelter bleed treatment plants worldwide with similar improvements in precipitation and filtration rates. HDS is a registered trademark of De Nora Water Technologies. RÉSUMÉ Cet article a pour objectif de rappeler aux chercheurs, aux concepteurs, aux exploitants et aux administrateurs les avantages de l’ensemencement dans la conception des étapes de précipitation de leur schéma de traitement. L’introduction d’un procédé des boues haute densité (procédé HDS™, de l’anglais high density sludge) encourage la formation de substances solides précipitantes à la surface des particules précipitées existantes. Cet article porte sur l’application de la technologie HDS à la fonderie Kennecott, où les auteurs ont observé des améliorations importantes au niveau de la vitesse de sédimentation et de filtration. Ils ont également appliqué cette technologie à diverses usines de traitement des rejets liquides des fonderies dans le monde entier, et ont constaté des améliorations similaires en termes de vitesse de précipitation et de filtration. Le procédé HDS est une marque de commerce déposée du fabricant De Nora Water Technologies.INTRODUCTION In 1966, the lead author worked as an assistant smelting metallurgist for the Tsumeb Corporation Limited copper and lead smelter in Tsumeb, Namibia. The smelter produced copper and lead, as well as cadmium and arsenic trioxide as byproducts. The cadmium was concentrated in the lead blast furnace off gas dust, and was collected by a baghouse. The baghouse dust was leached with dilute sulfuric acid (H2SO4) in a batch process. The iron and arsenic in the solution were oxidized with potassium permanganate (KMnO4) and basic ferric arsenate (BFAS; Fe(AsO4)x(SO4)y(OH)z·wH2O) was precipitated using milk of lime. The cadmium was cemented from the purified solution using zinc dust."

Jan 1, 2018

By Edward H. Robie

HOW have recent events affected the general trend in world mineral production? What effect has the World War, with its resultant boom and depression, had on the long-term trend of output? Have all of the principal metals and fuels been similarly affected, or have some boomed or slumped much more than others? The trend of world production of coal, iron, the principal nonferrous metals, and petroleum is shown in the accompanying chart, covering the period from 1882 to 1931 inclusive-the last fifty years. The curves are plotted logarithmically to show the comparative trends. In the lower left-hand corner of the chart is a slope diagram to aid in visually evaluating. the average yearly rate of increase in production; from this one can easily see, for example, that the petroleum production curve indicates an average annual increase of around 8 per cent, and that up to the period of the World War the average annual increase in copper production was about 6 per cent.

Jan 1, 1932

By Chris Blain

"Abstract - Based upon an extensive database, this paper analyzes the record of modern mineral exploration success and establishes the 50-year trends in discovery. The record clearly shows that the overall discovery rate rose during the 1950s and 1960s, peaked in the 1980s, and fell during the 1980s and 1990s. By commodity and ore-type target, the pattern of discovery is not continuous. Typically, it is episodic as a series of waves with minor resurgence. The waves reflect the order of the so-called discovery booms, led by uranium, then nickel, and copper, polymetallic base metals and gold. With the possible exception of gold, the discovery booms appear to be independent of metal price, although favorable perceptions of the price outlook may well have initiated the boom or led resurgence. Although difficult to quantify, an emerging trend in modern discovery is the integration of several detection techniques into the search process. No doubt, this trend will continue as orebodies become more and more difficult to find. The record of the past two decades shows that greenfield discovery rates have progressively fallen even though the level of investment in exploration has risen to an all-time high. This trend reflects increasing discovery risk. Several factors are contributing to this trend. Perhaps the two most important are: (1) deteriorating economics as increasing real costs and decreasing real prices continue to raise the economic hurdles for minimum acceptable exploration targets, and (2) increasing exploration maturity in many search terrains, particularly those in the traditional regions of North America and Australasia. To succeed cost-effectively in this new environment of increasing discovery risk will require extraordinary creativity, innovation, and technical skill coupled with commercial discipline."

Jan 1, 2000

By D. Hnrrington

THE Dust Symposium was attended by approximately 100 persons, nearly all of whom remained from the starting hour (2 p. m.) until the use of the auditorium was demanded for another meeting at 5:30 p. in. In calling the meeting to order, D. Harrington made a few remarks as to the importance of the health dust problem in mining as well as in general industry and expressed gratification that the subject is now out in the open and that mining people are desirous of ascertaining the facts. B. F. Tillson acted as chairman of the meeting. The milling executive who desires to know what to do to prevent his workers from being unduly exposed to the dust hazard can get much out of the paper by D. E. Cummings, who has been doing much work in mines trying to keep -the dust in the air within safe limits. His recommendations indicate that the main protection of the worker in mines is by adequate ventilation, supplemented by the extensive use of water in drilling, as well as in water curtaining to condition air both in regard to dust content and to temperatures. Blasting was shown to be one of the chief causes for dust and it was recommended that whenever feasible all blasting should be delayed to the end of the working shift.

Jan 1, 1935

By C. W. Parisi

Use of high-expansion foam for controlling mine fires was first made known in a published announcement in June, 1956, by representatives of the Safety in Mines Research Establishment, Buxton, England. In 1957, the United States Bureau of Mines, interested in this new method of controlling mine fires which could not be approached or extinguished by conventional methods, began to investigate the practicability of the foam-plug technique under American mining conditions at its experimental coal mine in Bruceton, Pa. Results of these experiments proved the potentialities of controlling mine fires with foam. The USBM conducted numerous demonstrations at its experimental mine to show this foam-plug method to groups of coal mining men, many of which were impressed by the action of the foam as it moved away from the netting toward an open fire and its ability to control the fire in a very short time.

Jan 2, 1961

By Robert E. Tally

The ore reserves of the United Verde Copper Co. in 1907 were estimated at 4,500,000 tons, averaging about 7 per cent copper. Seventy-five per cent of this tonnage was confined to the so-called fire stopes and the remainder was virgin ore. The fire area was being operated at a maximum capacity of 150 tons per day, and the other workings furnished the remainder of the ore, approximately 600 tons per day. The mine was developed to a depth of 900 ft. and the lower levels were considered lean and unpromising. The smelter had been built directly over the ore-bodies. Its site was congested, the ground was settling and maintenance costs were excessive. The major needs of the United Verde obviously were 1. Additional ore reserves. 2. A new and modern smeltery. 3. A method for the mining of the fire-stope ores commensurate with the tonnage and values involved. It is the method specified in point, 3 with which this paper is chiefly concerned. Such a method required the removal of the old smelter, and additional ore reserves were essential not only for the maintenance of production but for the investment necessary for the building of a new smelter.

Jan 1, 1932

By Sneddon NW

Aberdare North Colliery is situated on the eastern boundary of the City of Cessnock in the Hunter Valley, New South Wales. Although the area is now noted for its wines and vineyards, the district has a long history based on coal mining. The richest coal seam in the Cessnock district is the Greta Seam, a low ash, high volatile steaming or gas making coal. The seam, up to 10 metres thick, extends over a large area surrounding the city of Cessnock and neighbouring townships such as Bellbird, Aber- dare, Kearsley, Neath, Ellalong, Kurri Kurri and Stanford Merthyr. The Aberdare Colliery, leases, which extend under Aberdare and Cessnock townships, were first worked in 1905 and continued developing pillar panels until the mine closed on 11 Nov- ember, 1960. Coal mining to this time consisted mainly of developing pillars to the 2.4 metre parting and, in some areas, dropping the top coal to the 6 metre parting, thus leaving the pillars intact, the top 1.8 metr-es of coal be- ing left untouched due to the high sulphur content. Aberdare North Colliery was opened in 1956 in order to recover and extract the pillar coal and tops left standing for over 40 years. During the pillar extraction phase the occurr

Jan 1, 1981

The practice of pumping gases which inhibit combustion for purposes of controlling or extinguishing mine fires is now universally accepted. The practice has been used many times in coal mines in India and the experiences are reviewed. The procedures relating to a membrane based nitrogen generator and to a combustion gases generator are described. The physical properties, practical requirements and economic implications of using different gases is briefly reviewed. Some aspects of the practice as related to mine fires in certain collieries in other countries are dealt with.

Jan 1, 2000

"The profile of the respondents was that of a professional responsible for communications, community relations or corporate social responsibility programs. By targeting a consistent professional profile it was possible to ensure that most respondents had a similar degree of responsibility and/or decision-making ability related to the application of communication technologies. The research attempted to be inclusive and attention was paid to interview respondents from both genders and from indigenous groups.4, 5 A codebook of 80 themes was developed that highlighted recurring topics; for example, codes were created to identify risks, benefits, policies and learning process of using social media and included topics that were repeatedly emphasized by respondents (i.e. age, efficiency and language). Both manifest coding (i.e. coding of the visible content, such as specific words) and latent coding (i.e. coding of underlying meanings) was undertaken (Creswell [13]). The codes were used in the qualitative analysis using ATLAS.ti software and network views were created to illustrate the relationship between major themes of this research. There are limitations to this research, largely related to the changing nature of the Internet and communication technologies. There is also a geographic limitation to the application of this research because most of the data was gathered primarily from Canadian sources.6 Different levels of Internet penetration, or limited access to computers or mobile devices, and low literacy rates may reduce the applicability of the research in countries with low Internet penetration. A more systematic process to selecting candidates may have helped bring balance to the final list of interview respondents. For example, most of the corporate respondents were from medium and large companies and there was not adequate representation of small mineral exploration companies. The research did not probe into social media applications by different business groups within the mining sector, such as smelting and processing."

Jan 1, 2011

By Jerry Ran

When multiple levels are mined in open stope mining with delayed backfill, mining underneath fill is inevitable to achieve higher rate of recovery if no sill pillars are left for the purpose of fill separation or partial ground support. This is particularly true when the orebody has low reserves per unit vertical distance. Instability of the exposed fill back causes stope dilution, production delay and possible equipment damage and consequently increases the mining cost. Previous studies have concentrated on fill mat stability in cut-and-fill and stability of fill walls in open stope mining. Workers are exposed to the fill back in cut-and-fill and therefore smaller open spans are normally adopted and the fill mat is reinforced. In open stope mining openings with large spans are designed, workers are not exposed to the fill back and its stability has to be maintained by fill of sufficient strength. However, the required fill strength is normally determined by considering different modes of fill wall failure. The fill back stability is usually not analyzed in the fill design process. The lack of analysis on fill back stability for open stope mining is mainly due to difficulties in relating the fill properties to the fill and stope geometry. In this paper a simplified wedge model is adopted to analyze stability of the exposed fill back in open stope mining with consolidated backfill. The proposed method calculates the factor of safety of the fill back against shear failure under known fill and stope geometry and fill strength parameters in order to assess the fill back stability. It can also be used to determine the required fill strength with known fill and stope geometry. The proposed approach is indirectly validated by mining experience and observations at two operating mines. In addition there are many factors affecting the fill quality and stope configurations in an operating mine. These factors have to be considered in the analysis of fill back stability. This situation is highlighted by presenting an actual mining case where the fill back failed due to factors commonly encountered in mining operations.

May 1, 2003

By S. J. Patchet

The use of fill in deep-level gold mining presents the possibility of achieving considerable economic and operational benefits if conventional support can be eliminated. Unfortunately, the combination of the properties of tailings from gold reduction plants and the narrow, flat, tabular reefs being exploited make conventional hydraulic filling very unpractical. Laboratory tests indicate that, with careful control of water content, these tailings can provide an adequate fill material. A variety of bonding agents have been investigated, and the most practical seems to be ordinary Portland cement. Even at very low cement contents some cohesion is achieved. The design and layout for a complete fill support system using hydraulic transport, dewatering, and pneumatic placement are discussed, and a surface field trial indicated that the principles involved are correct and that acceptable results can be achieved. This system and material would completely eliminate conventional timber and brick support, and a preliminary economic analysis indicates that filling is cost competitive on a direct replacement basis. All the operations for a full-scale operation are available or have been developed to a stage sufficient to indicate that the system is practical, although certain operations require further refinement.

Jan 1, 1978

A filled stope is one in which the support for walls and men and, at times, for the back of ore, is furnished by waste rock or sand tailings. The filling may be rock sorted out in the stope or from the walls, develop-ent, or the surface. The orebody is mined in sections, each practically an open or timbered stope, filled wholly or in part before adjacent ground is attacked. As a rule, the filled-stope method is limited to overhand flat-back, stepped-face, or rill stopes. The examples given are Copper Range, Iron Cap, Verde district, Zaruma district, Lucky Tiger, and Silver King Coalition.

Jan 1, 1925

By Charles E. Lees

The Globe Mining District is in the southeast central part of Arizona, in Gila County. Globe, with a population of about 7000, is the terminus of the Arizona Eastern R.R., a branch line 130 miles long that connects with the Southern Pacific R.R. at Bowie. In 1874, prospectors crossing the Pinal Mountains from the west located what is generally known as the Old Dominion mine. For several years, it attracted little attention, because of the greater interest aroused by the discovery of high-grade silver ores in some of the foothills northeast of Globe. About six years later, the prospector turned his attention to the abundant copper ore revealed by surface workings along the Old Dominion vein, and, in 1884, the Old Dominion company erected two 30-ton furnaces. From 1888 to 1893, the Old Dominion company is said to have maintained an average annual production of about 8,000,000 Ib. of copper. Until Dec. 1, 1898, all supplies had to be freighted into Globe by wagons and the mines of the district operated intermittently because of high expenses, but with the advent of the railroad the Old Dominion company continued to be a large and steady producer. In the Globe district, the production of copper far exceeds in importance that of any other metal. There are four operating companies along the Old Dominion vein and the total annual product of these properties for 1923 was about 45,000,000 lb. of copper. The unit size of the mineral tracts in the district is the regulation mining claim, 600 ft. wide by 1500 ft. long, and all ownerships are held in fee. Globe is 3600 ft. above sea level, and lies between the Apache MOUntains to the east and the Pinal Mountains to the west. The principal drainage of the district is northward through Pinal creek into the Salt River. The general slope from the high point along the vein, where the Superior & Boston mine is, to Pinal creek, where the Old Dominion mines are, is about 250 ft. to the mile. Geology The oldest rocks in the district are pre-Cambrian crystalline schists known as the Pinal schist, which are the basement upon which all the later rocks were deposited. These latter rocks comprise shale, con-

Jan 1, 1925

By W. H. Schacht

The operations of the Copper Range Co. are located in the Michigan copper district at the southern end of the Keweenaw Peninsula, 8 miles southwest of Hough ton (the center of the district). All the producing mines are situated in a long narrow zone paralleling the peninsula and occupying the central portion. This zone is about 25 miles long and 3 to 4 miles wide. The important mines, in their order from northeast to southwest, are, Mohawk, Ahmeek, Allouez, North Kearsarge, Wolverine, South Kearsarge, Centennial, Calumet & Hecla, Osceola, Franklin, Quincy, Isle Royale, Baltic, Trimountain, and Champion; the last three are operated by the Copper Range Co. The existence of copper deposits in this district became known soon after the discovery of America. Many references by early explorers show that copper was found in the possession of many of the American Indians that inhabited the Great Lakes region. There is abundant evidence that exploration of these copper deposits extended into prehistoric times; and some indication that the American Indians carried on operations shortly before the advent of white men. An account of the finding of primitive mining appears in the Government publications of 1850-51 by Foster and Whitney. Although earlier expeditions by white men had been made to the Keweenaw peninsula, an attempt to commercialize the district was not made until after 1765, when Alex. Henry, a British subject, searched the shores of Lake Superior for mineral treasure. His first expedition took him to the Ontonagon River, where he found the famous mass of copper now on exhibition at Washington. In 1771, he started operations along this river with a crew financed by English capital; but after much difficulty and only meager success he found only detached masses while in search for a major deposit. There is no record of any cxploration from 1774 to 1820. In 1838, Dr. Douglas Houghton was appointed state geologist. Prior to that time he had made several visits to this region; and was the first white man to find

Jan 1, 1925

By C. E. Mills

The Verde mining district is in Yavapai County, in north-central Arizona. Jerome, the principal town, has a population of 6000 and the two important mines of the district—the United Verde and the United Verde Extension—lie almost within its limits. Perched high on the southwest side of the Verde valley, at elevations of 4800 and 5500 ft. (1463 and 1676 m.) respectively, both mines have long tunnels from their lower levels through which the ore is hauled to the smelters. Clarkdale, the smelter town for the United Verde mines, lies in the Verde valley 4.1 miles (6.5 km.) distant in an air line from Jerome and at an elevation of 3560 ft. The two towns are connected by the standard-gage railroad of the Verde Tunnel and Smelter R. R., a subsidiary of the United Verde Copper Co. This road is 11 miles long and has a compensated grade of 4 per cent. At Clarkdale it connects with the Verde valley branch of the Santa Fe railroad. Clemenceau, the smelter town for the United Verde Extension mine, lies 3.5 miles (5.8 km.) in a southeasterly direction from Clarkdale, at an elevation of 3420 ft. It is connected to the Verde Valley branch of the Santa Fe railroad at Clarkdale by the Arizona Extension R. R., a subsidiary of the United Verde Extension Mining Co. The portal of the haulage tunnel, at an elevation of 3757.5 ft., is also connected with the smelter town by 4 miles of standard-gage track belonging to the same company. In the vicinity of Jerome, the great southern escarpment of the Arizona plateau forms the northeast side of the Verde valley. The general level of this escarpment, or "rim" as it is called, is about 4000 ft. above the Verde River. A corresponding elevation is reached only by the highest peaks of the Black Hills, which bound the valley to the southwest. Two lava-capped mesas, known as "Mingus" and "Woodchute mountains," form the culmination of the Black Hills. That part of the Old Black Hills mining district which lies between their crests and the Verde River is now known as the Jerome, or Verde, mining district. If the smelter towns are not included, a strip about 7 miles long by 3 miles (11 by 5 km.) wide, embraces practically all of the properties belonging to the Jerome district. T-bis strip lies parallel to and along the side of the Verde valley from First View, 2 miles northwest from Jerome, to the

Jan 1, 1925

By Nikhil C. Trivedi, Robert W. Hagemeyer

Despite the apparently unflattering term filler, this group of industrial materials has become an essential component of many industrial products with varying degrees of sophistication. Mineral fillers are, by definition, inert materials included in a composition for some useful purpose. Included in this broad category are asbestos, barite, bentonite, natural calcium carbonates (limestone), clays, diatomite, feldspar, micas, silica, talc, and other industrial minerals. Also included in this category are synthetic mineral- derived materials such as aluminum hydrate, precipitated calcium carbonate, and pyrogenic and precipitated silicas and silicates. Mineral fillers are included in compounds to accomplish a variety of final results. Inclusion of fillers modifies physical characteristics such as hardness, brittleness, impact strength, compressive strength, surface texture, fire resistance, softening point, and electrical conductivity. Depending upon the performance characteristics of the particular filler used and the quantity of the usage (i.e., percentage added), these materials can enhance the physical and optical properties, price-performance, and appearance of the finished products. These enhancements in properties of the finished compounds are the result of properties of the fillers including chemical activity, purity, hardness, particle size, particle shape, particle size distribution, surface structure, color, density, and refractive index. This chapter will review the general usage of fillers, the rationale for their use, trends, and economic factors influencing those trends. Major using industries will be examined in detail with extensive discussion of major fillers used in those industries. The reader is referred to the appropriate commodity chapter for specific information on deposits and processing for industrial minerals. All of these same filler materials have additional significant uses based on their chemical composition or other characteristics. Cross-references for these will be found in other use chapters and summarized in commodity chapters. The chart in Table 1, updated from the 5th edition of Industrial Minerals and Rocks, illustrates the major mineral fillers (both natural and synthetic) and their more important end uses.

Jan 1, 1994

By Nelson Severinghaus

Mineral fillers have been defined as inert materials that are included in a composition for some useful purpose. Because this definition and the scope of this review are not specific- indeed, exceptions abound-accurate total statistics are unavailable. One source estimates the total production in the United States in 1971 at 5 million tons valued at $200 million, averaging $40.00 per ton. Included are a broad group of minerals-asbestos, barite, bentonite, calcium carbonate, clays, diatomite, feldspar, micas, silica, talc. Additional references will be made to synthetic mineral-derived fillers such as aluminum hydrate, precipitated calcium carbonate, and pyrogenic and precipitated silicas and silicates. A section on related uses at the end of this chapter covers absorbents and filters. Mineral fillers can be included in compounds to accomplish a variety of final results. Hardness, brittleness, impact strength, compressive strength, softening point, fire resistance, surface smoothness, electrical conductivity, and a host of other physical characteristics may be modified by the inclusion of fillers. These effects are the result of properties of the fillers, including chemical activity, hardness, particle size, shape and distribution, surface structure, color, density, and refractive index. To facilitate an overview of the mineral filler industry, this chapter will review the general usage of fillers, the inherent characteristics that intensify their utilization, and similarly their manufactured characteristics. Major using industries will then be examined in detail. Specific information on deposits and processing for industrial minerals will be found in the appropriate commodity chapter. The chart in Table 1, updated from the 3rd edition of Industrial Rocks and Minerals, illustrates the major mineral fillers (both natural and manufactured) and their more important end uses.

Jan 1, 1975

By Nelson Severinghaus

Mineral fillers have been defined as inert materials that are included in a composition for some useful purpose. Because this definition and the scope of this review are not specific-indeed, exceptions abound-accurate total statistics are unavailable. One source estimates the total production in the United States in 1979 at 11.3 Mt (12.5 million st) valued at $534 million, averaging $49.19 per ton. Included are a broad group of minerals-asbestos, barite, bentonite, ground limestone and dolomite, clays, diatomite, feldspar, micas, silica, talc. Additional references will be made to synthetic mineral-derived fillers such as aluminum hydrate, precipitated calcium carbonate, and pyrogenic and precipitated silicas and silicates. A section on related uses at the end of this chapter covers absorbents and filters. Mineral fillers can be included in compounds to accomplish a variety of final results. Hardness, brittleness, impact strength, compressive strength, softening point, fire resistance, surface texture, electrical conductivity, and a host of other physical characteristics may be modified by the inclusion of fillers. These effects are the result of properties of the fillers, including chemical activity, hardness, particle size, shape and distribution, surface structure, color, density, and refractive index. To facilitate an overview of the mineral filler industry, this chapter will review the general usage of fillers, the inherent characteristics that intensify their utilization, and similarly their manufactured characteristics. Major using industries will then be examined in detail. Specific information on deposits and processing for industrial minerals will be found in the appropriate commodity chapter. All of these same minerals have additional significant uses based on their chemical composition or other characteristics. References will be found in other use chapters and summarized in commodity chapters. The chart in Table 1, updated from the 4th edition of Industrial Minerals and Rocks, illustrates the major mineral fillers (both natural and manufactured) and their more important end uses. Use of Mineral Fillers Archaeologists have found that more than 5000 years ago, bitumen used for mortar and waterproofing contained mineral contaminants that acted as fillers. Since that time man has added mineral products to compounds to improve certain characteristics. Perhaps the most common objective of filler usage is reduction of cost of the end product. Certainly the inclusion of a filler that costs 2¢ per 0.45 kg (lb) will reduce the cost of a plastic product whose resin costs 50¢ per 0.45 kg (lb). But the decision to use a specific filler is not that simple. It may "soak up" binder, making a compound more viscous and perhaps preventing its flow into a mold as an injection molding compound, but similarly will give good anti-sag characteristics to putty, caulking compound, or undercoating. Fillers may be incorporated to modify: 1) Cost 2) Physical characteristics 3) Flow characteristics 4) Fire resistance 5) Density 6) Heat conductivity 7) Color or brightness and opacity 8) Hardness, brittleness, impact strength 9) Deformity, viscosity, softening point 10) Processing problems 11) Electrical conductivity 12) Surface texture 13) Thermal expansion characteristics 14) Abrasion resistance

Jan 1, 1983