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By André Vervoort

At the 2017 ICGCM-conference in Morgantown, WV, a case study was presented with measurements of the upward surface movements or uplift after the closure of two neighboring coal mines (Winterslag and Zwartberg, Belgium). One was closed in the sixties, and the other closed in 1988. The study was based on satellite data (Radar-interferometry or InSAR). The analyses showed both a significant variation of uplift values above the mined area and the surrounding zones, and a variation of the uplift rate as a function of time. In other words, the phenomenon of uplift is complex. At that time, it also was clear that more research was needed to better understand this phenomenon, e.g., an identification of the various mechanisms that are relevant for the process of uplift and the quantification of the various impacts. A systematic analysis of all relevant parameters resulted in a framework that forms the basis for the analytical calculations of uplift values. These calculations show that the main impact is due to changes in the hydrostatic pressure. However, the expansion of the softest parts, i.e., the collapsed or goaf material, is not only important, but the expansion of the (stiffer) non-collapsed strata layers due to a change in pore pressure also must be integrated into the model. For the case study, the partial flooding of the underground after closure of the mine that was abandoned in the sixties is integrated into the model. Larger stiffness values also are applied for this mine, in comparison to the values of the more recently closed mine. Overall, a very good correlation is observed between the InSAR-measurements and the calculated values along a north-south transect.

By Madan M. Singh

Although roof bolting has been a major means of strata support for nearly two decades, little attention has been directed towards the design of bolt Installations. The variables involved are interdependent and their study complex. However, some simple tests may be employed to serve as guides to the efficient design of roof bolt systems. Local conditions are continually varying and are important to pattern design. This paper discusses such considerations and suggests techniques which may be employed to effect improved roof control with bolts.

Jan 1, 1967

By Ewan Alexander

"As human beings, we have managed risk since the dawn of the ages and have been adept at doing so. In order to survive, we hunted or gathered. If we did not take enough risk, we died. If we took much risk, we died (Fig. 1). As individuals and tribes, risk had to be optimized to maximize our chances to thrive, as individuals and as tribes.In today’s world, the risks are vastly different, but in order to thrive, these must be managed. And no industry knows this as much as mining. In fact, the International Council of Mining & Metals (ICMM) has proposed the Critical Risk Model (Fig. 2) as a means of identifying critical risk, critical controls and associated performance standards. The ICMM focuses on sustainable development performance in the mining and metals industry. It has 23 members, representing some of the largest mining companies in the world.This approach is going to help the mining industry. But it must be applied effectively, with the acknowledgment that the system alone cannot be effective. We can say this confidently, as even companies known for the strength of their risk and safety management systems continue to experience significant incidents, and, in some cases, catastrophes. Why does that happen when all safety metrics, including injury rate, are pointing in the right direction? In the view of the author, it is only when leadership, culture and systems work in complete harmony that the resilience of an organization to manage its significant risk is at an optimal level. It remains an ongoing leadership challenge to maintain that balance and the optimal mindset in the organization. So how do you maintain that special balance?Let’s start with a basic premise. Leadership, supported by simple effective systems, creates culture which creates outcomes. Everyone going home safely is an outcome, as is cost effective operations, and to achieve those outcomes efficiently, the organization must focus on the inputs. And those inputs include effective leadership, effective systems (for the purposes of this article, risk and health, safety and environment (HSE) systems), good planning, stable operations and competent workers. This article will focus on gaining maximum performance from your risk management system."

Oct 1, 2016

By H. C. Juvkam-Wold

The design of an aquifer depressurization system is discussed. The system uses a number of wells surrounding a mine shaft to reduce the aquifer pressure in the vicinity of the shaft. The effect of various parameters such as number of wells, wellbore diameter, time and well location is discussed. It is concluded that, with a properly designed depressurization system, the aquifer pressure and the water inflow rate to the shaft may be reduced to less than 15X of their potential values in the absence of wells

Jan 1, 1980

By P. C. Fletcher, E. Kaya

The Bond grindability testing procedure has been standardized to measure the same grindability values, i.e. Bond work index (BWi), for the same ore when tests are performed in different laboratories or by different operators. This is accomplished by the standardization of mill dimensions, tumbling speed, grinding ball charge weight and distribution, sample ore charge weight in the mill and operating practice. The results of this investigation reveal that the Bond work index grindability values may differ substantially with different standard Bond ball mills. This paper will review the results.

Jan 1, 2002

By S. Shrivastava, R. G. Reddy

Spent potliner is generated in the electrolytic process of reducing alumina to make aluminum metal using molten fluoride electrolytes. Spent potliner (SPL), obtained at the end of the pots life contains a small amount of cyanide and fluoride which present environmental problems. SPL became a listed hazardous waste under RCRA (KO88) in July, 1990. One of the possible uses of spent potliner is as a substitute for Calcium Fluoride (CaF2) as a fluidizer in iron- and steelmaking and in the glass industry. A low viscosity and a low melting point are prime requirements for accomplishing the above. In the present study, viscosity measurements were performed. Effect of various additives, such as sand, limestone, dicalcium silicate dust, and MgO baghouse dust on the viscosity of SPL was studied. The results showed that with the addition of sand and limestone, very high fluidity of SPL melt can be obtained at significantly low temperatures. The results suggest that spent potliner mixed with additives could potentially be used as a substitute fluidizer.

Jan 1, 1999

By Earl M. Frizzell, Ronald W. Utley

Introduction For the past several years the Bureau of Mines has undertaken research to develop alternative mine material haulage systems that will improve mine productivity, reduce haulage costs, increase mineral availability, and conserve energy. One basic concept being pursued is a means for crushing primary blasted rock to a size that can be reliably and economically moved on conveyors. During 1980, mine requirements for this equipment and the capability of existing technology to satisfy these requirements were assessed. The study continued into 1981 on the basis that satisfactory equipment for this purpose needed to be developed. The objective of the 1981 program was to perform an engineering design of such a system. A mine survey and equipment development study was conducted in cooperation with the open-pit mining industry by GATX through its subsidiaries, Fuller Co. (a crusher manufacturer) and GARD Inc. (GATX's research and development center), under contract to the USBM. Results of a mine survey in the copper, iron, and molybdenum industries indicated that a universal crusher system could be developed even though details might vary from mine to mine. The crushing characteristics, including tonnages desired, were similar in all surveyed mines. Most mines had similar views about the desirability and frequency of crusher movement. The perceived need for in-nit crushing varied between copper and iron mining. The copper mines felt a greater sense of urgency for introduction of such a system, probably because typically greater vertical haulage is found in copper mines than in the iron mines. All mine personnel surveyed were interested in portable crushers and almost universally preferred gyratory-type primary crushers. They preferred large crushers, citing inherent reliability and durability, and the machine's relative freedom from clogging. Large size minimizes the number of crushers and conveyors needed. Analysis of desired crusher system characteristics (Table 1) fixed the crusher size at 1.5 x 2.3 m (60 x 89 in.). The 1.5-m (60-in.) feed-opening dimension could accept the largest material normally fed to the crusher, and the 2.3-m (894n.) head diameter could fulfill the 3.63 kt/h (4,000 stph) capacity requirement. Selected System Description The comments and analyses discussed in the contract report led to the design and refinement of a movable crusher system. This system represents the consensus of more than 100 mine workers and almost 50 construction and engineering company personnel. It is supported by more than 50 years of experience in crusher manufacturing. Although many alternatives are available for any given system, and selections are likely to be dictated by varying site conditions, the selected system is believed to be appropriate for most projected requirements. Final design would be dictated by mine operators during evaluation for approved projects. Detail design of the feed and discharge systems were not included in the study because they are mine specific. The basic system (Fig. 1) consists of a 1.5 x 2.3-m (60 x 89-in.) gyratory crusher on a structural steel frame. The frame is used as an operating platform for the crusher and as a carriage to move the crusher. The control tower includes a crusher lubrication room, a hydraulic equipment room, a switch gear room, a room for the motor control center, and a control room for operating the crusher and maintaining the equipment. The auxiliary system consists of a hydraulic rock hammer and pedestal crane with 74-t (80-st) and 14-t (15-st) hooks. Figure 1 also shows stairs, railings, and a work platform. Feed and discharge arrangements are shown on Fig. 2. The system shown is for mildclimate applications. Additional enclosure and heating would be needed for extremely cold weather conditions. Crusher A 1.5 x 2.3-m (60 x 89-in.) gyra¬tory crusher was selected for this application. This size can handle the typical throughput of 3-3.63 kt/h (3,500-4,000 stph) desired by the mines and the 1.3-m (50-in.) material to be crushed without difficulty. The crusher is the heaviest

Jan 4, 1983

By L. Barry Phelps

The application of an open-pit Materials Handling Simulator (OPMHS) to analyze mine planning and scheduling problems in large surface mines is discussed. The mine chosen for this application employed a large stripping dragline working in tandem with a shovel-truck haulback system for removing overburden. Large bottom-dump trucks were employed behind a coal loading shovel to transport the exposed coal out of the pit. Specifically, the current operations and the recommendations for short term and long term improvements were simulated on OPMHS. The effects of changing the operating parameters of the equipment on the total system were evaluated. Several alternatives were also studied for the best use of the existing equipment if the current operating parameters could not be improved upon. The results of the application are discussed.

Jan 1, 1978

By W. W. Wen

The objective of this investigation was to study the electrokinetic behavior of oxidized coals to indicate the feasibility of separating oxidized coals from ash materials and pyrite by an mine flotation process. The effects of soluble inorganic electrolyte products from coal oxidation were also examined. The electrokinetic behavior of coals of different rank and degree of oxidation were studied by an electrophoreses technique. Generally, increasing the oxidation increases the negative value of the zeta-potential and decreases the isoelectric point (IEP). Flotation results indicate that the flotation recovery increases with decreasing pH values, and that with ferrous sulfate at pH 6.5 the flotation recovery is optimum while the pyrite was depressed. Comparing the flotation results with the electrokinetic results verified that in the presence of ferrous sulfate, the maximum hydrophobicity of oxidized coal with dodecylamine and frother is near its IEP which is around pH 6.5 to 7.0.

Jan 1, 1976

By Doug Brown

The recent expansion of our cities into hilly areas, particularly on the Pacific Coast, has resulted in damage or destruction of many homes due to geological problems such as landslides, soil creep, erosion, subsidence, or groundwater seepage. In southern California, landslides are the principal cause of damage and attention is focused on them. Landslides have occurred due to the reactivation of old slide masses, or have been caused by grading and increased water, infiltration resulting from development.. Reactivation of a portion of the ancient Portuguese Bend landslide in Palos Verdes, Los Angeles County, affected approximately 150 homes. A common type of new failure' occurs when grading has undercut bedding or other essentially planar surfaces so that they dip unsupported out of slope. Other slides have occurred due to the inherent weakness of the material involved. Preventive measures undertaken to eliminate damage in the southern California area have. included areal geologic mapping programs-in-advance of development, enacting or strengthening grading codes, and requiring extensive studies by consulting geologists and soils engineers both during the design stage and during construction. In the design stage, proposed cuts are frequently flattened, lowered or reorientated. Frequently, due to the high cost of land, they are supported by compacted fill buttresses. As a result of these measures, the geologic environment has a major effect on the feasibility, design, and development of, a very substantial percentage of tracts or individual homes.

Jan 1, 1967

By M. Scaggs, L. R. Mendoza

"On January 9, 2014, a large chemical spill occurred on the bank of the Elk River near Charleston, WV. Within hours, the potable water supply for more than 300,000 people was contaminated, and the incident captured national headlines for weeks. Although the primary chemical, crude 4-methylcyclohexanemethanol, or MCHM, is deemed nonhazardous, the impacts of the spill are significant – with all stakeholders, including the public, members of industry, and relevant government agencies experiencing losses. This case highlights the need for a more proactive approach to environmental management, shifting from crisis control and remediation to crisis prevention and risk management. INTRODUCTION On the morning of January 9, 2014, approximately 10,000 gallons of crude 4-methylcyclohexanemethanol (MCHM) leaked from a 48,000-gallon storage tank sitting on the bank of the Elk River near Charleston, West Virginia (WVDEP, 2014; CSB, 2014). MCHM is a chemical commonly used in preparation of fine coal, and is deemed nonhazardous in terms of transportation and storage regulations and also toxicity (CDC, 2014a). Freedom Industries, Inc., a producer and vendor of specialty chemical products, had acquired the storage facility where the spill occurred from Etowah River Terminal, LLC just a few weeks prior in December 2013 (WVDEP, 2014; Freedom, 2005). The direct cause of the spill was ultimately determined to be two small holes in the base of the 76-year-old tank, which were created due to corrosion damage (Bauerlein & McWhirter, 2014). The spill site was located just over a mile upstream from the intake of a municipal water treatment facility operated by West Virginia American Water (WVAW), which serves a population of 300,000 across nine counties in central West Virginia (CDC, 2014a). In a matter of hours, the leaked MCHM made its way through the treatment facility and into the water of nearby homes and businesses, where its strong smell was noticed almost immediately. On the evening of the spill, WVAW concluded that its conventional treatment processes, which include carbon filters to remove a variety of contaminants from water, were not capable of fully removing the MCHM and a “Do Not Use” order was issued for all customers (WVAW, 2014a). With little information readily available regarding the potential human health effects of MCHM, the US Centers for Disease Control and Prevention (CDC) quickly issued an advisory ruling that set a maximum screening level of 1 ppm for safe drinking water (CDC, 2014a). Based on this recommendation, the “Do Not Use” order remained in effect for a total of eight days, until January 17, when the WVAW distribution water was confirmed to have MCHM concentrations below this level (WVAW, 2014a). However, due to the pungent odor of the chemical, its presence was still recognizable in the WVAW facility and in consumers’ tap water after the order was lifted (Manuel, 2014). Recent studies have shown that the chemical can be detected in water at concentrations as low as 0.55 ppb by individuals experienced in odor identification (Rosen et al., 2014); and even individuals with no such training can detect pure MCHM at just 7 ppb (WVTAP, 2014). The fact that this chemical can be sensed at such low levels – indeed far below those considered safe – undoubtedly added to growing public concern. In response to numerous complaints and demands, WVAW continued flushing the treatment facility and pipes until February 25 when MCHM levels were measured below 2 ppb (WVAWb, 2014), and eventually replaced the affected filter media (WVAWc, 2014)."

Jan 1, 2015

By LaTasha R. Swanson, Jennica L. Bellanca

Proximity detection systems (PDSs) for mobile machines have the potential to decrease injuries and fatalities. Early adopters of the technology have identified some challenges, which present an opportunity to explore and improve the integration of mobile PDSs in underground coal mines. The current research study applied the task-technology fit framework to investigate the fit between mobile PDS technology and mining relative to health and safety, from the perspective of leaders at two coal mines. Quantitative results from the study show that mine leaders evaluated mobile PDS favorably for training and ease of use, system feedback, user authorization and experience, and less favorably for safety, compatibility, task completion, and reliability. Qualitative results reveal specific task, mine, and system characteristics that may have influenced leaders’ evaluations. The study includes considerations and suggestions for safe technology integration

By John M. Moore

Within the Pofadder district of Namaqualand, South Africa, economically exploited deposits of bedded barite and zinc-lead-silver-copper sulfides occur in close proximity within highly metamorphosed mid-Proterozoic pre-tectonic para¬gneisses of the Namaqualand Metamorphic Complex (NMC) (figure i). The paragneisses belong to the Bushmanland Group (SACS, 1980) that comprises a relatively straight-forward regional sequence of basal leucogneisses, intermediate mica-sillimanite schists and glassy quartzites, and a mixed upper zone of banded iron formations (BIF), minor marbles, quartz muscovite schists and localised uppermost quartz-pebble conglomerates and amygdaloidal mafic gneisses (Joubert, 1974) (figure ii). The base metal and barite mineralisation occurs in close association with BIFs, generally above the glassy quartzites, although in some cases possibly below them. In the regional context, the Bushmanland Group paragneisses are, to the north, intercalated with and ultimately replaced by meta-volcanic sequences of talc-alkaline affinity (Reid, 1977) belonging to the Orange River Group (SACS, 1980). The metavolcanics are generally of acidic to intermediate composition and show evidence of subaerial formation from 'high altitude shield volcanism' with many acidic ashflow and welded tuff bands, mesocratic and lesser melanocratic lavas and some fanglomerates (Ritter, 1980). To the south and east, the schist/quartzite associations are initially intercalated with and eventually replaced by cordierite gneiss/metacarbonate/biotite gneiss associations of shallow marine affinity (Moore, 1980a). The Bushmanland Group paragneisses appear to represent sedimentary material in the extreme distal portions of a talc-alkaline volcanic environment adjacent to a shallow platform sea.

Jan 1, 1983

By A. E. Ketler

Conventional Atmospheric Monitoring System (AMS) installations for monitoring CO, CH4, O2 and air-velocity throughout underground mines are usually relegated to a modest 3-5 mile extent and with data communication speeds confined to a ponderous 1-5K baud range. New US-MSHA and state regulations require fast reporting of unsafe conditions, and the old 20-30 minute updates are no longer acceptable. To communicate farther and faster has always been a problem, because data reliability degenerates with excessive distances and high speeds. Because of this, very large mines often resort to costly optical-fiber media, using expensive OF cables and repeaters to obtain the necessary coverage. This entails high initial cost, as well as high maintenance and downtime costs to repair or replace broken optical fibers. Rel-Tek has pioneered with its DX-Bus communication data highway, which uses inexpensive twisted-pair telemetry cables, which can now communicate well into the 20-mile extent of the largest mines -- normally a brick wall for low-tech AMS systems. This extended range, enables the use of twisted-pair cables and provides a low cost alternative to OF systems. This paper discusses the DX-Bus, and its latest accomplishment, the ?B-LINK,? a unique high-speed communication repeater that maintains the 19.2K-Baud data rate. On-going innovations to our workhorse Millennia-DX computer software have kept pace with this extra speed/distance phenomenon, resulting in a dually-optimized AMS package: both hardware and software. Cost savings are substantial, and at no sacrifice of reliability ? nearly always at 100%. Sensor updates are measured in seconds, not minutes and hours. Twisted pair copper cable is cheap to purchase and install and a breeze to maintain. Rel-Tek uses the B-LINK's wide branching capabilities to enable the AMS to extend 20-miles both far and wide. Actual experience in large US coal mines -- both longwall and continuous mining operations -- confirms the large mine performance. The ventilation and safety benefits to the mining industry are immeasurable.

Jan 1, 2009

By A. D. S. Gillies

Diesel engine particulate matter pollution is a matter of concern currently in underground mines worldwide. A number of real-time Diesel Particulate Matter (DPM) monitors have been developed in recent years; two of these by the National Institute of Occupational Health and Safety (NIOSH) in the US. One, the D-PDM, is based on an adaption of the successful NIOSH?s Personal Dust Monitor (PDM) unit which is being taken up very successfully for mine respirable dust monitoring. The D-PDM measures all particulate matter within a sub-micron range as classified nominally at 0.8 micrometers by a purpose developed cyclone. The other, the FLIR Airtec, measures the Elemental Carbon (EC) component of DPM by a laser scattering approach. Both instruments have been evaluated underground in robustness and reliability testing in coal mines by the authors. Real time DPM monitors allow greater understanding of the sources and levels of DPM pollution in underground activities. They allow engineering evaluations to determine how conditions can be improved or mining personnel relocated to lower concentration levels. Studies are discussed that examine DPM concentrations from vehicles under varying ventilation conditions. Some of these concern tests undertaken during high activity longwall face moves. They focus on evaluating DPM during the various phases of the face Chock Shield moves. An initiative in some mines has been to limit the number of vehicles in the mining section or panel by the use of a Tag Board or Traffic Controller at the panel travel road entrance to manage exhaust DPM and gases. Diesel tags or tokens are used to control the number of vehicles entering a section or panel and so limit level of pollution. Summation of DPM levels from points monitored throughout a panel demonstrates increasing DPM levels from influence of additional equipment in series within the ventilation circuit. An alternative approach is to invest in underground continuous real-time monitoring of exhaust gases, DPM and section air quantity and integrate this information to determine whether an additional vehicle can enter without exceeding diesel target limit. This optimizes the access of diesel vehicles and replaces the existing manual tag board system. Real-time DPM monitoring allows the industry to pin-point high exposure zones such as those encountered where various vehicles work in areas of constrained or difficult ventilation. Identification of high DPM zones allows efficient modification of mine ventilation, operator positioning and other work practices to reduce underground miners? exposures.

Jan 1, 2012

By Edmund H. Warner

Any city dweller who has walked alone along a remote mine passageway has to be impressed by the eerie silence - the total absence of noise except for ones own breathing and scuffing of boots on the bottom. An underground mine can have tremendous contrasts, from complete silence to the ear piercing clatter of percussion drills working on the mine roof. Noise in underground mining machines is both useful and detrimental. Without characteristic noises that are recognizable to miners, operators would have a more difficult job operating their machines. Noise serves as a warning of approaching machinery, and changes in noise give indication that breakdowns may occur. But excessive noise is a health hazard. In recognition of this fact, our Congress included noise exposure as a part of the "Coal Mine Health and Safety Act of 1969". As Fig. 1 indicates, allowable noise exposure is established by specifying a time duration permitted at different noise levels. This is the well known "Walsh-Healey" criteria which governs noise exposure in many industries.

Jan 1, 1977

By David G. Abbott, Frank Coluccio

This paper will discuss the construction of nearly 165 m (540 ft) of 3.5. m (138 in) o.d. reinforced concrete pipe to replace an existing utilidor under the Duwamish River in Seattle, Wash. The project required that two 27.4 m (90 ft) deep shafts be installed for use as jacking and reception shafts during the tunneling operation, and permanent vaults once completed. Soil conditions to be excavated consisted of soft saturated sand and silt with a 21.3 m (70 ft) water head. This required the shafts to be constructed using ground freezing techniques and the tunnel installed by pipe jacking, using a Mechanical Earth Pressure Counter Balance (MEPCB) slurry shield. The original utilidor was constructed between 1924 and 1925, and has since been deliberately flooded because it is considered to be structurally unsound.

Jan 1, 1995

By Fred Morelko, Michael Connelly, Brad L. Ricks

INTRODUCTION The $1.1 billion Bajo la Alumbrera Project, started up in 1997 by Minera Alumbrera Limited in the Catamarca Province of Northwestern Argentina, is the first large scale modern mining project to be developed in Argentina. Like many modern Andean mining projects, existing infrastructure was not available to economically transport the 875,000 tonnes of product per year. A variety of alternatives were investigated, including upgrading of existing roads and railroads, slurry pipelines, and combinations of these systems. The final system selected was to combine a 312 km slurry pipeline with an 820 km rail haul to a ship loading facility near Rosario. The concentrate pipeline crosses divergent terrain between the minesite at 2400 m elevation and the filter plant at 400 m elevation. The system selected represented the lowest net present cost alternative by a significant margin. BACKGROUND The Bajo Alumbrera deposit was discovered in 1947 by Professor Cetioni from the University of Tucuman. It is a large (>750 million tonnes) medium-grade (0.6%) copper deposit with high gold values (0.5 g/t*). The deposit outcrops, making it very suitable to modern, large scale, open pit mining techniques using 218 t trucks and 43 m3 shovels. Advances in gravity concentration of the gold helped to demonstrate the feasibility of the project in a study prepared by Fluor Daniel for Minera Alumbrera in 1994. The initial concentrator is the largest green-field concentrator ever constructed, rated at 85,000 t/d. Production will peak at 190,000 tonnes of copper metal and 710,000 troy ounces of gold per year, one of the top 10 copper and top 15 gold producers in the world. * Throughout this paper, the word tonne and abbreviation refer to the metric ton of 1000 kg.

Jan 1, 1998

By S. Al-Thyabat

In this work, the floatability of Jordanian phosphate slime (-38 µm) was evaluated in a batch column flotation cell, 100 cm high and 5 cm inner diameter. Flotation was conducted using sodium oleate as a collector and methyl isobutyl carbinol (MIBC) as frother. Rougher flotation yielded concentrate assaying 29.19% P2O5 with 90.29% recovery at the following flotation parameters: 2.6 cm/s superficial gas velocity, 20 ppm frother dosage, 0.205 mM collector concentration and 40% weight solids. It was also found that conditioning with the same collector dosage but with a different solids weight percent gave different flotation results. However, pulp collector concentration was the key operating parameter; increasing collector dosage at the same solids weight percent decreased flotation recovery by 3%, while increasing solids weight percent at the same collector dosage increased phosphate recovery by 18%.

Jan 1, 2011

By E. R. Dotson

Kaolin is an important industrial mineral. It has unique properties, which combined with its low cost, make it suitable for use in a wide variety of products. Kaolin is defined as "any of a group of clay minerals, including kaolinite, nacrite, dickite, and anauxite, with a two-layer crystal in which silicon-oxygen and aluminum-hydroxyl sheets alternate; approximate composition is AlZ03-ZSiOZ-1/ ZHZO".-The kaolin discussed here is composed chiefly of the mineral kaolinite. Kaolin is also commonly referred to as "china clay". Approximately 4.9 kkg (5.4 million short tons) of kaolin was sold or used in the United States, and .8 million kkg (.9 million short tons) was -exported in 1974. In domestic usage, paper coating and filling accounted for 43% of the total, fol-2/ lowed by refractories, rubber, and ceramics.-Figure 1 shows the amount of kaolin sold or used by domestic producers for specified uses for the years 1963-3/ 1973.- Kaolin was produced at mines in 14 states, but Georgia accounted for 75% of the 1974 domestic production. The average value for all grades was $36.00/kkg 4/ ($32. 67/ton) .-

Jan 1, 1977