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In 1990, US mine production of barite increased 54.1 %. Barite consumption, sold or used by grinding plants, increased by 27.6%. Imports were about the same as 1989. World mine production in¬creased 12.3%, according to the US Bureau of Mines. The value of domestically produced barite, fob mine, decreased 12.7%, according to the Bureau. The declared value, cif US port, of all imported crude barite during the year 1990 increased from $40.27/t ($36.54 per st) in 1989 to $40.61/t ($36.84 per st). Nevada continued to be the leading producer of barite with 82% of the total, followed by Georgia and Missouri. It is estimated that 750/c, of the domestically mined barite was used as a weighting agent in drilling fluids. The remaining 25% was used in barium chemicals, glass or as a filler. Most of the production from Missouri, Georgia and Tennessee was used in the non-oilfield sector. Of the total barite used by grinding plants and chemical manufacturers, it is estimated that 90% was used in drilling fluids and 10% in the non-oilfield sector. This includes barium chemicals and fillers in paper, plastics, and glass. Tonnage consumed in the drilling fluids market increased due to the higher average rig count during 1990. The average number of rotary rigs operating, (1010), was 16.2% more than the 1989 average of 869 in the US.

Jan 1, 1991

By William H. Meadows

This information describes the ventilating and methane gas testing procedures utilized during the raising of a mine shaft using a Robbins 81-R drill. An overview of the raise boring process is presented to illustrate the ventilating and gas testing procedures. A mine shaft project, 4.88 m (16 ft) in diameter and approximately 457.2 m (1500 ft) in length, will be the focal point of the presentation, with reference to similar projects for additional comments on variations in procedure.

Jan 1, 1980

By David W. Lillie, Pier A. Abetti

This paper reports on a study of the impact of fast growing new technologies on the market for copper over the next 15 to 20 years. The greatest threat is clearly the inroads of fiber optics on the traditional market for copper in communication cable. Opportunity areas identified include heat pumps, solar power and heat, desalination, electric vehicles and others. The overall impact of new technologies on copper is expected to be modestly positive if adequately encouraged by effective R&D.

Jan 1, 1986

By G. Van Weert

Oxygen transfer from dispersed air in agitated slurries represents an important unit operation in the minerals processing industry. Gold leaching, iron precipitation and especially bio-oxidation come readily to mind. However, little engineering information is available on the variations between impeller types on such O2 transfer. Engineering literature on the subject, i.e. information which relates slurry density and energy input to O2 transfer, is reviewed and compared to current experimental work. The latter was carried out with minus 50 micron sand/water slurries in a 64 I laboratory tank of standard proportions, equipped with a variable speed drive with torque meter. A standard Rushton turbine and a specifically sized A315 were compared. Results confirm an increasing impairment of O2 transfer with increasing slurry density for both impellers. The volumetric mass transfer coefficient, k,a, in a 10 vol. % slurry shows a decrease of 30% compared to the k,a in water. At 20 vol. % sand this decrease is near 50 %, depending somewhat on superficial gas velocities. Power efficiency, i.e. the kg O2/kWh, decreases about 25 % more rapidly for the Rushton turbine than for the A315 with the addition of sand. However, for equivalent O2 transfer the Rushton turbine was more efficient in this work. Experimental results are presented and their significance for slurry bio-oxidation discussed.

Jan 1, 1996

By Lynda T. Holden, Philip L. LeHoux

Barneys Canyon Mine is a 1.8 million t.p.y. gold heap leach operation near Salt Lake City, Utah. The gold recovery plant has been operating since September of 1989. Carbon elution is done at atmospheric pressure with a high temperature caustic solution. No cyanide is used in the process. Operating experience is discussed.

Jan 1, 1990

By Geno Saccomanno

INTRODUCTION Cancer of the lung in uranium miners has been reported by many authors. In fact, it has become a most popular subject for comment by environmentalists, health physicists, and newspaper writers. I believe it appropriate for me to discuss cancer of the lung in uranium miners in a general way commenting briefly on etiology, incidence, tumor cell types, and particularly, tumor development and treatment. Cytological development of cancer in its incipient stages, particularly the in situ stage, relates to potential cure with photoradiation, early diagnosis, and treatment. Our observations of the cytological response to this modality of diagnosis and treatment will be discussed briefly since this area will also be covered by Doctor Balchum. The cause of lung cancer in uranium miners is primarily due to two carcinogens; cigarette smoking and radon daughter radiation. Cigarette smoking has continued at the same intensity over time among uranium miners; about 60% of the miners are cigarette smokers and 40% are non-smokers. Radon daughter exposure to the uranium miner has varied from mine to mine, but over the last 20 years has been reduced to a minor fraction (.3 WL) of the level that prevailed in many of the mines during the 1950-1960 era when many of the miners were exposed to more than 10 WLM. Sputum samples have been examined on as many uranium miners as responded on the Colorado Plateau since 1956. Autopsy studies were done whenever this was permissible. In some instances, only tissue from a biopsy of a node or lung was available for study. Smoking histories were also taken. Approximately 200,000 sputum samples were examined and histological examinations of lung lesions were made from 312 cases. METHODS The method of sputum cytological collection and preparation was reported previously. I The lungs were fixed with formalin and prepared for sectioning by Dr. Oscar Auerbach with his block-section method. RESULTS Three-hundred-twelve lung cancers from uranium miners were examined. The tumor types and the age at death for each type, smokers and non-smokers, are given in Table #1. The incidence of the tumors in the smokers and non-smokers is given in Table #2. The incidence of small cell carcinoma of the lung has decreased from an incidence of 76% of all the lung cancers found in uranium miners to 22% of these lesions (Figure #1). The decrease in incidence of this tumor is probably due to decreased exposure to radiation in the mines.

Jan 1, 1981

By P. Wearden, K. Bryner, K. Vrana, V. Castranova, R. Dey, R. Reist, J. Blackford

INTRODUCTION Proliferation and enhanced synthesis of collagen by pulmonary fibroblasts have been shown to be key steps in the development of chronic silicosis (Goldstein and Fine, 1986). The regulation of lung fibroblast proliferation by cytokines released from alveolar macrophages may be an important pathogenetic mechanism in the development of the fibrotic process (Kelley, 1990). One cytokine, platelet-derived growth factor (PDGF), promotes fibroblast proliferation by inducing the movement of quiescent (Go) cells into the C1 phase of the cell cycle (Chen and Rabinovitch, 1989). Others regulate the rate of transition of fibroblasts from Gl into the S phase (Leof et al., 1982). These two classes of cytokines have been termed, respectively, competence and progression factors. One approach used to examine the release of cytokines from macrophages is the fibroblast proliferation assay in which fibroblasts are exposed to culture supernatants from macrophages exposed to various stimuli. In most of these assays, the supernatant contains fetal calf serum which provides the competence factor(s) necessary to facilitate the proliferation of fibroblasts (Bitterman et al., 1982; Bitterman et al., 1983; Elias et al., 1988). Recently, a fibroblast proliferation assay using plateletpoor plasma (lacking competence factor(s)) as a substitute for fetal calf serum has been described (Kuman et al., 1988; Bauman et al., 1990). In this assay, the release of a competence-inducing PDGF-like growth factor from rat and human macrophages can be distinguished from other cytokines that act as progression factors. In order to obtain more consistent results and with the ultimate goal to be able to discriminate between the effects of competence factors as opposed to progression factors, we have conducted experiments to determine the appropriate concentrations of plasma and PDGF required for imparting competence in the fibroblast proliferation assay. We tested lung fibroblast cells obtained from explants of rat lung tissue and also a fetal human lung fibroblast cell line obtained from American Tissue Culture Collection (ATCC153). MATERIALS AND METHODS Fibroblasts Specific pathogen-free, male Sprague-Dawley rats were use in some studies. Animals were given a lethal intraperitoneal dose of sodium pentobarbital. Fibroblasts were isolated by chopping the lung in enzymes that digest the connective tissue but liberate lung cells for further study (Rabovsky et al., 1989). After digestion, the remaining lung tissue suspension was filtered through two layers of sterile gauze and centrifuged to recover lung fibroblasts. These were resuspended in culture medium that contained 10% fetal calf serum and distributed to culture plates for growth. In other experiments, a human fetal lung fibroblast cell line, obtained from American Type Culture Collection, Rockville, MD, 20852, was used instead of rat lung fibroblasts. In these cases, a 1 ml ampule containing human fetal fibroblasts was plated into a tissue culture flask containing medium plus 10% fetal calf serum. For both types of fibroblasts, culture medium was changed 3 times per week and cultures were incubated at 37°C until confluent. Harvested rat and human lung fibroblasts were quantified using an electronic cell counter equipped with a cell sizing attachment (Coulter Electronics, Inc., Hialeah, Florida). Tritiated Thymidine Incorporation The basic procedural outline of Kumar et al. (1988) was used with modifications to evaluate tritiated thymidine incorporation into fibroblast DNA following exposure to PDGF and plasma. Both rat and human lung fibroblasts were plated at 50,000 cells/ml at a density of 250,000 cells/25cm2 culture plate. Cells were quiesced for 4 days with 2% rat plasma. As the assay was refined, fibroblasts were quiesced in plasma-free media for 48 hrs, since the mitogenic activity of 2% plasma was variable. Test medium was applied for a period of 6 hrs, followed by a 24 hr tritiated thymidine (lµCi/ml) labelling period in plasma-free media. Medium alone was used as a negative control and media with 10 or 20% fetal calf serum was used as the positive control for rat and human fibroblasts, respectively. Cell Quantification and Measurement of Mitogenesis Twenty-four hours after the addition of tritiated thymidine, the fibroblasts were washed with 5ml of fresh serum-free media, centrifuged and resuspended in phosphate-buffered saline. The cells were dissolved in 0.5m1 of O.1N NaOH and radioactivity determined in a beta counter. Incorporation of trititaed thymidine as an index of DNA synthesis was expressed as DPM/fibroblast. RESULTS In the present study, we quantified mitogenic potential by monitoring the incorporation of tritiated thymidine as

Jan 1, 1991

By Orville L. Lantto, Bruce K. Cantrell, Keith S. Olson

Approximately 10 to 20 pct of exhaust aerosol mass from diesel equipped vehicles operating without exhaust controls is attributable to particles in the 1.0-10 µm size range. Recent in-mine measurements suggest that, in addition to reducing overall exhaust aerosol mass concentrations, the use of waterbath exhaust conditioners (water scrubbers) may significantly reduce the concentration of diesel exhaust particles larger than approximately 0.5 µm aerodynamic diameter. This implies that a measurement system that discriminates between diesel and mineral dust aerosols on the basis of aerosol size would have different accuracies depending on use of a water scrubber. To test this hypothesis, laboratory measurements were made by the Bureau of Mines to determine diesel exhaust aerosol penetration efficiency through a water scrubber as a function of size and engine operating conditions. Size distributions were determined using a Micro-Orifice, Uniform Deposit Impactor. Concentrations of CO, CO2, NO x, O2 and gas-phase hydrocarbon concentrations were also measured. No significant effect was found for these gases other than a slight decrease in NOx emissions. The water scrubber served as a moderate aerosol control with reductions in mass concentrations of about 29±9 pct under most conditions. This reduction occurred for particles less than 0.2 µm and greater than 0.6 µm aerodynamic diameter. Coal dust aerosols are mostly larger than 0.8 µm aerodynamic diameter. With use of a water scrubber, separating the aerosol into two parts, greater and less than about 0.8 µm aerodynamic diameter during sampling, results in collection of diesel and coal dust aerosol accurate to within 10 pct. Without a water scrubber in operation, such a sampling protocol would only be accurate to approximately 15 pct.

Jan 1, 1991

By M. J. Lowe

National Institute for Occupational Safety and Health (NIOSH) studies show that 43.5% of surveyed coal preparation plant workers had noise exposures exceeding the Mine Safety and Health Administration Permissible Exposure Level. Sound levels around vibrating screens in these plants often exceed 90 dB(A). NIOSH is currently developing noise controls for horizontal vibrating screens. To characterize noise sources, NIOSH researchers performed sound pressure level (SPL) measurements on a vibrating screen at their Pittsburgh Research Laboratory. The results show that the entire screen contributes to noise below 1 kHz and the vibration mechanism housings are most significant above 1 kHz. Constrained layer damping (CLD) treatments and an enclosure were used to reduce mechanism housing noise. These were evaluated using sound power level measurements according to ISO 3744. The CLD treatments reduced the A-weighted sound power level by 3.1 dB in the 1 to 10 kHz one-third-octave bands. A panel-on-frame vibration mechanism enclosure using various types of panels further reduced the A-weighted sound power level from the CLD configuration in the 1 to 10 kHz one-third-octave bands by 3.7, 4.0, and 3.9 dB for aluminum, steel, and Dynalam panels, respectively. The combination yielded a 7 dB reduction from baseline in A-weighted sound power for the same frequency range.

Jan 1, 2010

By Yong Yuan, Wenhao Xiao, Luc Taerwe

"The static shear stiffness of an immersion joint subjected to combined compression and shear forces is investigated by experiments in a test set-up. To explore the performance of the immersion joint, the compression-shear loads, which are applied on a specimen according to test protocol, are determined based on real design situation. In this test, the main focus is on the steel shear keys and the rubber sealing. For the applied loading schemes, different levels of axial force, corresponding to the water depth of the joint, are considered as well as the changing amplitudes of the shear force. The force-displacement curve is obtained and the hysteresis is observed during the whole test. The joint‘s static shear stiffness is calculated, showing to increase linearly with respect to the magnitude of the axial force. Moreover, it is found that the rubber sealing has a significant influence on the shear behavior of the joint. INTRODUCTION An immersion joint is the connecting part between two adjacent elements of an immersed tunnel. Compared to that of the bulk elements, the stiffness of the immersion joint is relatively small. When it is subjected to shear actions, whether resulting from vertical foundation settlement or horizontal earthquake movements, shear-resistance of the joint is the main concern for a safe and reliable water-proof design. A flexible immersion joint, which normally consists of a rubber seal and shear keys installed at an element end is a common solution in practice. The way in which the shear keys and the rubber seal behave in the joint together is of vital importance to a comprehensive understanding of the shear behavior of the joint. However, in literature very few experiments on the shear behavior of immersed joints are available although the flexible joints are applied in practice for more than 50 years already. O. Kiyomiya (2004) carried out both a 3-dimensional experiment and a finite element analysis for a new type of flexible joint referred to as the Crown Seal. The results indicated that this new type of joint can be applied in practice because of the effective reduction of lateral deformation. A linear model was found in the paper of Anastasopoulos et al. (2007) to describe the behavior of the shear keys, which consider that the stiffness of the shear keys tends to infinity. R.S. van Oorsouw (2008) discussed the shear capacity of concrete shear keys in segmental joints, by analyzing the influences of reinforcement and friction force between shear keys."

Jan 1, 2016

Production In 1993, it was estimated that United States mine production of barite increased 24%. Barite consumption, either sold or used by grinding plants, increased by 39% and imports increased 4%, according to the US Bureau of Mines (USBM). Nevada continued to be the leading producer of barite with 80% of the total, followed by Georgia. It is estimated that 83% of the domestically mined barite was used as a weighting agent in drilling fluids. The remaining 17% was used in barium chemicals, glass or as a filler. Most of the production from Missouri, Georgia and Tennessee was used in the non-oilfield sector. Prices The value of domestically produced barite, f.o.b. mine, decreased 1%, according to the USBM. The declared value c.i.f. US port of all imported crude barite during 1993 decreased from $40.09/t ($36.37/st) in 1992 to $37.72/t ($34.22/st). Uses Of the total barite used by grinding plants and chemical manufacturers, it is estimated that 90% was used in drilling fluids and 10% in the non-oilfield sector. This included barium chemicals, fillers in paper, plastics, brake shoes and glass. The tonnage consumed in the drilling fluids market increased due to the higher average rig count during 1993. The average number of rotary rigs operating in the United States was 754, 5% greater than the 1992 average of 717. Imports Crude barite imports in 1993 were 443 kt (488,000 st) greater than 1992, representing an increase of 137%. Imports accounted for 67% of the barite consumed (apparent) in the United States.

Jan 1, 1994

By Hayward B. Oblad, Gary F. Meenan

Two optoelectronic detectors were developed by CONSOL R&D for fine coal processing applications. One sensing device is used to estimate the amount of fine coal in the solids fraction of the froth flotation tailings slurry. The other probe, based on similar technology, is capable of measuring sol ids concentrations as high as 10 weight percent in fine coal slurry streams. These patented optoelectronic sensors are installed in several CONSOL coal preparation plants and are an integral part of the fine-coal control systems.

Jan 1, 1993

By A. G. Belova

Conversion of coal into high-value gases via gasification offers significant pollution reduction and efficiency improvement benefits associated with controlled combustion of clean gases for power generation. However, current gasification-based electricity production technologies, such as IGCC do not address carbon dioxide emissions. The focus of the study is CO2 capture on CaO prior to combustion of coal-derived gases. To overcome kinetic and stability limitations associated with its utilization, CaO is distributed on high-surface area -Al2O3 and supported on a ceramic honey-comb monolith. The proposed method allows for efficient capture of CO2 from a gas mixture, as studied in a flow-through reactor system. This novel method of CO2 capture is used here to argue for pre-combustion capture of CO2 in coal gasification-based power plants. When CaO is present during the steam reforming of coal gasification gases, continuous withdrawal of CO2 from the system provides for higher yields of reforming products (hydrogen gas) by influencing the thermodynamic equilibrium of the entire system.

Jan 1, 2009

By B. Stewart

Recent ore pass failures have underlined the need for improved designs, standards, structural monitoring methods, and better hang up prevention and removal techniques. Researchers at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) are investigating methods to improve safety during transport of ore in ore passes. Design criteria and hang-up prevention and remediation strategies involve studies of the effects of static and dynamic ore and waste rock loads on chutes, walls, gates, and support structures. Particle flow analysis methods were used to simulate the response of various ore pass designs to a wide range of ore loading conditions. A full-scale mock-up of actual ore pass and chute assemblies was duplicated and tested for load response. Data from a particle flow code and the mock-ups were com-pared. Loads on an active ore pass chute were measured.

Jan 1, 1998

By S. Eugene Sankey, Geoffrey L. Payne

Fundamental choices in flocculant selection often come down to the lower cost of solid grade products versus the convenience of liquids. The ideal product would be a low cost solid grade flocculant which requires minimal handling and no sophisticated dissolving equipment. Recent polymer developments have lead to the commercialization of a limited range of dry polymers that can be screw fed at controlled rates directly to process streams without the need for predissolving. Other developments include dry polymers that can be directly added to mix tanks without the need for sophisticated wetting systems. The latter will make dry flocculants especially attractive for smaller users. Examples of these new products and their application in industrial and municipal waste treatment will be provided.

Jan 1, 1994

By James I. Mathis

Should an arbitrary reduction factor be applied to laboratory compressive strengths when designing pillars? The answer is, as is the main contention of Peng's article, probably not. Many factors affect the strength of the material remaining in the pillar. On the other hand, outside influences will influence the strength testing results from the lab. This is not the first article, nor the last, to discuss the discrepancy between the two strengths. As was discussed in the article, actual pillar strength is affected by several factors. The two mentioned were: • The scale effect of discontinuities. How large must the pillar be so that the increase in discontinuity count with size will not decrease the strength. • Non-uniform strengths and lithologic units within the pillar. The scale effect of discontinuities is important. What size block must be tested so that the rock mass strength is actually measured? For a highly fractured rock mass, or coal with a high cleat density, this sample may be quite small. Conversely, if an unaltered, moderately jointed, quartz monzonite was examined, the sample block would likely be very large. This is the subject of ongo¬ing research. More to the point, if the tested sample is sufficiently large to model the rock mass strength, then no reductions should be made in the lab strength based on this factor alone. Non-uniform strengths and variations in lithologic units will also affect the pillar strength. I am not an expert in coal mines, having gained my experience in hard rock metal mining. These problems, though, are commonplace. However, strength sampling for pillar strength determination involves sampling material from within the lithologic unit that will form the pillar, not from pieces of material found on the floor. In addition, this sampling should cover the entire range of strengths of the material in the pillar-hard units (such as the partings described by Peng), as well as soft units. Testing results should then be included in the pillar design. Contrary to statements in Peng's article, at least one rock mass rating system (Laubscher, 1990) allows for the compositing of strong and weak units into a design rock mass strength that can be used for pillar design.

Jan 1, 1993

By Pradip

It is possible to beneficiate low-grade phosphate ore slimes containing predominantly siliceous gangue by a combined selective flocculation-flotation scheme using commercially available reagents. The presence of clays, in particular, montmorillonite and attapulgite, has a disastrous effect on the efficiency of separation. Suitable remedies to overcome this problem are not yet available. Intensive R&D efforts are required in the areas of the design and synthesis of specific reagents, the effect of particle size, and the design of appropriate process equipment to carry out flocculation and flotation of slimes.

Jan 1, 1989

By K. S. Eric Forssberg, Lennart Ryk

The paper discusses coal utilisation in Sweden. All hard coals have to be imported from other countries. Peat from domestic sources is used as a complement. Environmental legislation and taxation on fuel and emissions are severe. This situation affects the procurement, preparation, handling and use of coal. The paper presents: • R&D projects concerning deep cleaning of thermal coal. • Handling and treatment of coal used in PFBC boilers and for blast furnace injection • Dust prevention for coal and peat briquettes. Procurement of coal emphasising quality and environmental issues.

Jan 1, 1995

By M. A. Reyes, L. Yan

"Heat and humidity buildup within refuge alternatives (RAs) may expose occupants to physiological hazards such as heat stress. Mine Safety and Health Administration (MSHA) regulations require RAs in underground coal mines to provide a life-sustaining environment for miners trapped underground when escape is impossible. RAs are required to sustain life for 96 hours while maintaining an apparent temperature (AT) below 95°F (35°C). NIOSH tested a 10-person tent-type RA, a 23-person tent-type RA, and a 6-person metal-type RA in NIOSH underground coal mine facilities to investigate the thermal environment over a 96-hour period. The test results showed that mine air and mine strata temperatures surrounding an RA occupied by simulated miners increased over the 96-hour test period. The test results suggest that RA manufacturers should consider this increase in temperatures when calculating and evaluating RA components during surface and laboratory tests. The findings can equip stakeholders with additional considerations for calculating heat and humidity temperature profiles for RAs not tested in situ. INTRODUCTION RAs are designed to provide a life-sustaining environment for miners who cannot escape after a mine disaster. One of the major considerations for integrating RAs in mine environments is the thermal environment inside the RA and the impact that the surrounding mine conditions have on the temperature and humidity buildup. Previous research has observed that the metabolic heat of the occupants and the heat released by the CO2 scrubbing systems will cause the RA interior air temperature to increase. In addition to the increase in temperature, an occupant’s respiration and perspiration, as well as the chemical reaction of the scrubbing chemicals with CO2, will contribute to an increase in humidity within the RA. The resulting internal thermal conditions, if not controlled, can subject miners to conditions that can lead to heat exhaustion, heat stroke, or even death depending on the duration and magnitude of exposure. Apparent temperature (AT) is a temperature-humidity metric for the perceived temperature caused by the combined effects of air temperature, relative humidity (RH), and wind speed. It is used to assess the perception of indoor temperatures when workplaces are not sufficiently heated, cooled, or insulated to provide comfortable or healthy conditions. Mine Safety and Health Administration (MSHA) regulations require that RAs must be designed to ensure that the internal AT does not exceed 95°F (35°C) when the RA is fully occupied."

Jan 1, 2018

By G. Rainville, I. Servi, F. Katrak

Despite the severe drought conditions that reduced farm requirements for industrial mineral products, most industrial minerals markets in 1988 continued their growth or, at worst, remained flat. Earlier projections of output declines did not materialize in most segments. Preliminary estimates of demand in Europe and Asia show strong growth for most industrial minerals. Profitability in industrial minerals in North America was best in those minerals that had a significant export market or were not strongly regional. Growth and price trends in the more regional industrial minerals markets in the US such as sand and gravel, crushed stone, and cement, more closely followed the broadly disparate regional economic conditions. For example, sand and gravel and crushed stone grew strongly in the Pacific Coast and northeastern markets but not as much as in the Southeast. Total growth for sand and gravel in 1988 is projected at about 3% above 1987 levels. Combined production is up about 27 Mt (30 million st) to 2 Gt (2.2 billion st). Following the relentless trend of foreign acquisition of US cement companies (currently about two-thirds are owned by foreign interests), several aggregate operations have been purchased by foreign companies. Notable among these in 1988 was the acquisition of Rinker Materials Corp. by CSR of Australia. The acquisition of this Florida-based aggregate and concrete operation will expand the current holdings of CSR in the southeastern US, with operations consolidated under the Rinker logo. In addition, Pike Industries of New England and J.L. Shiely Co. of Minnesota were significant aggregate producers that were acquired by foreign firms. New England's only cement manufacturer, Dragon Products, was acquired by a subsidiary of Cementes del Norte of Spain. Dravo continued to expand its influence in the lime and limestone markets. It became the major supplier of construction aggregates on the inland river system with its purchase of Cyprus Minerals' limestone aggregate operations in Kentucky, Louisiana, and Texas. Although lime production continued to grow from 14 to 15 Mt (15.7 to 16.7 million st) in 1988, lime imports decreased for the fifth consecutive year to 145 kt (160,000 st). In the more export-oriented industrial minerals markets, performance was generally very good for 1988. Soda ash enjoyed an excellent year, with its price up to $102.50/t ($93 per st). This reflected the tight market situation for soda ash, particularly in late 1988. Soda ash production in 1988 was 8.6 Mt (9.5 million st), reflecting the industry's improved efficiency. Particularly significant was the increase in caustic soda prices that led to increased substitution by soda ash. The export market remained at 2.1 Mt (2.3 million st). Phosphate production recovered to the 42 Mt (46 million st) level, a 12% increase despite a soft export market. The price, however, remained soft throughout the year. W.R. Grace sold its interest in its Florida phosphate mine and its phosphoric acid complex as part of its divestiture of the agrichemicals business. The strengthening of the major producers has continued as lower cost capacity has been idled. Future permitting of phosphoric acid facilities and development of reserves will be necessary to maintain current production levels beyond the mid- to late 1990s. Despite new developments worldwide in the titanium minerals market, strong demand has continued to apply pressure to price, with concentrate and slag prices going up. The demand for high quality slag as feedstock for pigment production has resulted in process improvements in South Africa (Richard's Bay) and in plans by Canada to import high quality ilmenite by 1991 to produce a 90% TiO2 slag. Although growth in industrial silica sand applications was small in 1988, concentration in the industry continued. Unimin continued to acquire silica operations. Unimin is now the nation's leading producer of granular silica. The end users of silica have consolidated further. Owens-Illinois purchased Brockway Inc., a leading container glass producer. Three companies now control 75% of the container glass industry. ECC continued to be an aggressive purchaser of industrial minerals operations throughout the world. It acquired Cyprus Minerals' calcium carbonate business as well as two operations in Italy. In addition, ECC continued its aggressive acquisition of kaolin (Australia) and aggregate producers. 1988 was a good year for industrial minerals markets worldwide. More importantly, though, it was a year that showed continuing consolidations of reserve ownership in the industry around the world. Barite AN. Castelli, Baroid Drilling Fluids Inc. US mine production of barite decreased 9.4% during 1988. Consumption (sold or used by grinding plants) increased by 37.9%. Imports are estimated to have increased by 21.2%. World mine production decreased by 9.8%, according to the US Bureau of Mines. The value of domestically produced barite, fob mine, decreased 4.6%, according to the Bureau. The declared value cif US port of all imported ground barite during the first 10 months of 1988 increased from $37.16/t ($33.71 per st) in 1987 to $37.92/t ($34.40 per st), according to Bureau figures. Nevada continued to be the leading producer of barite with 72% of the total, followed by Georgia and Missouri. The Bureau of Mines estimates 69% of US mine production was used as a weighting agent in drilling fluids. The other 31% was used in barium chemicals, glass, or as a filler. Most of the production from Missouri, Georgia, and Tennessee was used in the non-oilfield sector. Of the total consumption used by grinding plants and chemical manufac-

Jan 1, 1989