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By Daniel H. Stevenson

Safety and health are fundamental values at Barrick Goldstrike. An effective safety and health program protects employees, controls costs and increases productivity. Barrick Goldstrike believes that all occupational injuries and illnesses can be prevented and that safety must be the responsibility of every employee on the property. Safety and health must be thoroughly integrated with the company's efforts to maximize production at the lowest reasonable cost. The goals of safety and production are not mutually exclusive. They must work together to achieve safe production. Barrick Goldstrike began to mine the Betze deposit in 1987. From 1987 to 1992, Barrick employed a traditional safety system using safety specialists on each crew. These specialists were responsible for ensuring that the work areas were safe and that employees were properly protected and trained in safe work procedures. As the work force increased, it became apparent that this system was not the most effective method of ensuring safe production. In 1992, Barrick Goldstrike implemented a loss control program. It was modeled after the International Loss Control Institutes's (ILCI) International Mine Safety Rating System. This program was based on the philosophy that safety is a management responsibility. It can be managed in the same manner that production and cost issues are managed. Under the loss control system, safety needs are identified and evaluated. Programs with performance standards are developed and implemented and the activities and results are regularly monitored. Between 1992 and 1996, Barrick Goldstrike worked at developing and improving its safety management systems. These efforts had a positive return. The incident rates began to decline as these improved systems were implemented. Studies were undertaken in early 1996 to evaluate the effectiveness of the safety and loss control programs in reducing accidents. The studies showed a strong correlation between the implementation of the loss control programs and the resulting reduction in all accidents. Studies in the process division revealed that Barrick had experienced reductions in personal injury accidents from the projected number that could have been expected had no changes been instituted. These reductions ranged from 39% in 1993 to 59% in 1995. These reductions from the projected rates held true for all types of accidents; personal injury, property damage and Mine Safety and Health Administration (MSHA) reportable.

Jan 1, 1997

By J. Ainsworth, W. Trudel, L. Schutz, C. L. Bolin

Newmont mine geologists have added substantial economic value developing over 1,150 tonnes into quality surface and underground gold reserves since 1986. However, the recent 5-year gold price slump from $387 to $262 per ounce has shifted mine geologists focus to optimizing open pit profitability and developing high-grade, high cash flow and low capital development underground reserves. More than $65 million projected revenue has been added to the Gold Quarry south layback following multi-departmental model reconciliation investigations. Kriged mine polygon construction, controlled blast heave and high-quality geologic advice in selective mining will have multi-million dollar beneficial impacts.

Jan 1, 2002

By Asa Weber

With continuing pressure from stockholders not only to maintain but to increase mineral revenues, producers have increased plant capacity. Depressed mineral prices have accentuated the trend toward higher production rates to maintain consistent cash flow, and these same trends have promoted the development of large-scale processing equipment. In addition to the need to handle increased throughput, larger flotation equipment can result in decreased capital-equipment and operating costs. The development of larger column and conventional flotation equipment relies, in part, on suitable scale-up procedures. To properly scale-up large flotation cells and columns, certain constraints and design parameters must be taken into consideration, including velocities in the vessel, residence time, solids suspension, and lip loading. This paper will review the design constraints and scale-up criteria for WEMCO® flotation cells. Scale-up criteria are augmented with computational-fluid- dynamics analyses and high-speed imaging techniques, as well as multiple regresesion analysis of in-plant operational data.

Jan 1, 1999

By David Morrison

On the Corramandel Peninsula of New Zealand, the Waihi Gold Mine has undergone a major redevelopment. The upgrade included the construction of two very large overland belt conveyors, both rated for a capacity of 6000tph. The first of these conveyors (CVR2) traverses a total of 1600m over undulating terrain, including a significant section running through tunnels. A large hill is climbed, just after the mid-section of the conveyor run, before dropping back down prior the discharge point. The second of these conveyors (CVR8) traverses 1100m along an alignment with a horizontal curve, a number of vertical curves and a significant lift before the discharge point. The CVR8 conveyor also included a shuttling head pulley arrangement. The mine they service is inside the town of Waihi. The conveyor alignment runs through the town and out to the metallurgical process site on the outskirts of the municipal area. This paper documents the engineering process that took place in the design of these conveyors. The Martha Hill mine in Waihi, New Zealand is unique. The mine is placed in the township. Consequently there are quite stringent environmental limitations on the mine's operation. In [Figure 1] the proximity of the mine to the town is shown. In the top-centre of the photograph the alignment of the existing smaller overland conveyor can be seen leading from the mine to a tunnel through the hill in the background.

Jan 1, 2000

By A. J. Hendron, B. Mohraz, R. B. Peck

INTRODUCTION The state of the art of soft-ground tunneling was discussed in detail by the senior author at the 7th International Conference on Soil Mechanics and Foundation Engineering held in Mexico City in 1969. Little can be gained by repeating the information assembled at that time. Hence, in this report, only the briefest summary will be given of the overall state of the art and attention will be concentrated on trends and developments since 1969. A characteristic of recent developments is the continued trend toward use of shields and excavating machines. The implications of this trend with respect to design and construction, and particularly with respect to the treatment of unfavorable ground conditions, will be examined. Settlement associated with lost ground, a subject as old as tunneling itself, will be reviewed and methods will be considered for its reduction. Design of tunnel supports was discussed in detail in 1969 with respect to essentially rigid or essentially flexible types of linings. In this report, a definition of flexibility will be considered and design procedures suggested for linings of flexibility intermediate between the two extremes.

Jan 1, 1997

By Jue Kou, Fazhao Sun, Jiang Liu, Cuili Gui, Baoqiang Yu, Chunbao Sun

A novel special magnetic separator was developed based on the special properties of precious metal-bearing alloy in highgrade nickel matte. The recovery of Au, Pt, and Pd was 77.79%, 84.79%, and 81.79% respectively at optimum operation conditions of magnetic separator feed of 2.5t/h, pulp density of 45%, and flush water of 1.5t/h, and the recovery significantly improved comparing with normal magnetic separator. Magnetic field simulation of the special magnetic separator indicates that magnetic intensity of 0.6 T can be generated on the surface of magnetic drum, which can strengthen the recovery of heavy alloy that contains precious metals. The alternate strong and weak magnetic field can also make magnetic particles rolling on the surface of drum, which will reduce the generation of magnetic agglomeration to a large extent and decrease the content of impurities in magnetic concentrate.

Jun 16, 2022

By Babcock. C. O.

This report presents equations derived from experimental testing to convert borehole pressure cell data from vertical and horizontal cells to the biaxial ground stress changes. While hydraulic pressure cells in boreholes have been in extensive use since 1957, methods of data reduction have been slow to develop. The methods of Sellers (1970) and Bauer et al. (1985), respectively, indicate a linear relationship between cell pressure change and the rock stress change. Lu presented a theory for creep behavior (Babcock et al., 1982). In the present work, in laboratory testing, the logarithm of the cell pressure was related to the stress change in seven elastic materials for a range of Young's moduli of 3.45 to 85.5 GPa (0.5 to 12.4 x 106 psi). The gage response depends upon the setting pressure of the gage, the gage pressure at any time, the rock properties, and the cross-sensitivity of the gage to transverse loading. The setting pressure of the cell should be proportional to the Young's modulus of the rock, the absolute stress can be determined by overcoring in strong rock, and the in situ Poisson's ratio can be estimated in some cases from the cell responses.

Jan 1, 1986

By T. M. Karppanen

Shotcrete is used both in mining and tunnelling for supporting rock. Both dry and wet processes are used for shotcreting, and each produces good quality concrete. Thick shotcrete layers function as a concrete arch supporting loose rock. Thin layers prevent relative movements between the blocks of rock due to the fine concrete in the cracks and joints. No progressive fallouts occur since key blocks are kept in place. Rockbolts are often used together with shotcrete in order to create an arch around the tunnel making the rock to support itself. Shotcrete is sprayed either manually or by means of mechanized equipment. The aim is to spray required the layer thickness in one pass and with a minimum amount of rebound. Sprayed layers should also be as even as possible. The tip of the nozzle should be moved in circular movements. The shotcrete should be sprayed at a right angle to the rock surface; the optimum distance from the nozzle to the application surface must be found by experiment. In a mine shotcreting forms a materials handling system which includes batching, transporting and the actual shotcreting. The equipment used vary depending on the spraying method, mining conditions and the location of the mine. Shotcreting is performed with a purpose-designed unit in most cases where operation is mechanized. The shotcreting unit consists of a spraying machine with a hose and a nozzle, an additive system, a manipulator and a mobile carrier with all the necessary controls and accessories. The key element of the unit is the shotcreting manipulator which holds and guides the nozzle as required. The manipulators currently in use are hydraulically operated, and their remote controlled booms are also often called robots. These manipulators have enabled users to increase their output capacities, to remove the operator away from unsafe areas and from the influence of dust and rebound. Furthermore, they improve the shotcrete quality and reduce shotcreting costs.

Jan 1, 1989

By Jorge Lanza

SUMMARY La Granja copper deposit, in terms of volume, is among the five largest deposits in the world and represents reserves of three thousand million tones. The field consists of a 40 m. thick layer of copper lying over the secondary ore and further down the primary copper. The flotation process has indicated a recovery rate of 88 to 90 percent and concentrates of 27 to 32 percent of copper. The acid leaching process of low grade ore produces financially acceptable results. To carry out the project, it is necessary to build long distance pipelines and a port. Both the Feasibility Study and the Environmental Impact Study on the project have been approved by the Peruvian government. INTRODUCTION La Granja is located in the district of Querecoto, province of Chota, in the department of Cajamarca, in the Northwest of the country (Figure 1). Geographically it is situated on the eastern slopes of the Andean mountains at an altitude of 2,000 to 2,700 m.a.s.1. (Figure 1). The site is an 8 hour car ride from the city of Chiclayo, capital of the department. The first 60 km. are over a paved road and the remaining distance is over a narrow hard dirt road. The copper porphyry of La Granja was discovered between 1969 to 1971 during some geochemical prospecting activities carried out by the State mining institution, Ingeomin (currently Ingemmet). From 1978 to 1982, Ingemmet continued with its geochemical and geophysical studies supported by a German technical assistance program. A total of 19 bore- holes were drilled (5,814 m.) and a 90 m. long tunnel made. This study calculated reserves of 175 million MT. In 1993, Minero Peru drew up a technical-financial study based on the above studies and proposed a 12 year extraction operating program: 20,000 MT daily using the leaching process, followed by 13 years of operation using the flotation process with the same daily volumes. In 1994, Cambior Inc. won an international auction in order to carry on further exploration work and to have a purchasing option. Since that date the company

Jan 1, 1998

By J. C. Adams

Although explosives constitute only a small portion of a mine's total cost, the relative success of each blast has a tremendous effect on subsequent activities such as excavation, crushing, and equipment maintenance. Beginning in January of 1993, tests were carried out to determine whether productivity could be improved by replacing standard ammonium nitrate fuel oil mixtures (ANFO) with a high density, high performance blasting agent. The study was carried out at gold mines, coal mines, and cement quarries in Nevada, California, Colorado, and New Mexico. A wide variety of rock types and blasting conditions were encountered. Results showed that at most operations productivity was sufficiently improved to more than offset the increase in explosives cost. This resulted in a net reduction in mining cost. This paper presents a summary of these results.

Jan 1, 1996

By Richard L. Bullock

Drilling of small diameter blast holes in the conventional tunnel driving system or mining operation still consumes a significant part of the time and money required to extend an opening in rock. The use of pneumatic drills for most small hole applications has been the dominant tool used by miners and tunnel men alike throughout the world. But now, a, trend has been started that is showing major inroads into the traditional areas of pneumatics drilling for all types of rocks. Operators dealing in very soft materials, such as coal, salt or potash, traditionally had the option to use hydraulic power for their drilling tools. Twelve to fifteen years ago, drillers in medium hard, but nonabrasive rock extended their drill machine option by helping to develop a drill that still used air to power the hammers, but relied on hydraulic power for the rotational torque and feed thrust. (1) This was a significant step forward, particularly for those who drilled in rocks that were compatible to rotary-percussion bits. However, this application was in fact somewhat limited to the limestone and dolomite formation of mid-United States and the softer sediments in Europe. Now high performance rock drills have been developed, using all-hydraulics for both the hammer and rotation, that have many advantages over the conventional pneumatic systems. In two previous papers on this subject, (2)(3) this author reviewed in detail: 1) the characteristics of each of the manufacturer's products that were on the market; 2) The specific advantages of the all-hydraulic drilling systems; 3) Data from the applications of these drilling systems that was in use; 4) What was needed to further develop this drilling system and utilize its potential in the mining or tunnelling cycle. This paper will attempt to update previous papers, without reiterating many details of drill descriptions or

Jan 1, 1976

By D. D. Snyder, J. D. Bode, F. T. King

INTRODUCTION Only in recent years have the environmental hazards associated with mining and tunneling operations been fully acknowledged and determined remedial action undertaken. The nature of these excavation operations leads to a wide diversity of hazards spanning mechanical, electrical, chemical, environmental, and physiological. The most insidious of these are unquestionably the environmental ones which have the greatest long-term effect and are the most difficult to pinpoint and monitor. It is the atmospheric contaminants that lead to a significantly greater illness and mortality rate among miners. Dust is the most prevalent, hence most important of the atmospheric contaminants. Respirable particles lead to diseases characteristic of many mining operations: coal workers pneumoconiosis, asbestiosis, silicosis, talcosis, anthrocosis, etc. But toxic and suffocating gases can be equally insidious and the most innocuous pollutant, methane, leads to the most imminently disastrous results of all - explosion and fire. This means that truly effective monitoring of the environmental hazards in tunneling cannot be limited to a few simple standard check measurements. It must include the most precise measurements we can make for specific, documented hazards and even for factors, such as noise and heat stress, not immediately obvious as hazards. The Federal Metal and Nonmetallic Mine Safety Act and more recent Occupational Safety and Health Administration standards are clearly designed to match such effective monitoring. We must, therefore, consider not only presently available monitoring instruments and those currently under develop-

Jan 1, 1997

By D. Kang

The adsorption behavior of silver in ammoniacal solutions on to activated carbon has been studied. The parameters affecting the adsorption of silver on to activated carbon included temperature, agitation speed, concentration of cations and anions as well as that of ammonia. It was found that the adsorption of silver from ammoniacal solutions was dependent upon the initial silver concentration in the solution and other factors. The recovery of silver from ammoniacal solutions was found to be not so effective as the case with gold reported earlier. The adsorption rate was relatively slow overall, despite a rather fast initial adsorption. The apparent activation energy for the adsorption was measured to be 30.2 kJ/mol. It was believed that the kinetics of the silver adsorption on activated carbon was limited by a mixed control mechanism.

Jan 1, 1998

By Richard H. Gates

INTRODUCTION The U. S. Army Corps of Engineers is developing chemical explosive excavation as a construction technique for use on Civil Works projects. Large chemical charges are being used in multiple charge arrays in a variety of media and topographic situations to achieve actual construction projects. The target is the development of chemical and nuclear explosive excavation as an accepted cost-competitive construction technique. Military research using explosive excavation is also being conducted to apply this technique to military engineering for combat purposes and to military construction. The information gained from both the civil and military research is integrated into the overall development of explosive excavation. This research and development work is being conducted under the auspices of the U. S. Army Engineer Waterways Experiment Station Explosive Excavation Research Laboratory (EERL) located at Livermore, California. This organization was formed in 1962 as the Nuclear Cratering Group (NCG) to carry out the Corps of Engineers (OCE) portion of a joint agreement with the Atomic Energy Commission (AEC) to develop nuclear explosives for construction purposes. The AEC, through the Plowshare Division of the Lawrence Livermore Laboratory at Livermore, California, has been responsible for developing nuclear explosives, conducting nuclear cratering experiments, developing nuclear safety information, and developing methods for predicting the shape of the craters. The Army part of the program includes corollary chemical high-explosive cratering experiments, participation in the AEC's nuclear cratering experiments, and development of

Jan 1, 1997

By S. D. Thompson

Conveyor belt haulage has become the preferred mainline transport method in under-ground coal mining, especially for multi-unit mines. Optimum designs for belts (width and speed) and surge bins (placement, capacity, and discharge rate) are necessary for minimizing haulage cost. Two computer simulation models, CMaCS and BELTSIM, available for optimizing these designs are compared. These comparison include: modeling, input data requirements, statistical flexibility, accuracy of simulated loading, and execution time.

Jan 1, 1989

By James N. Grassby

Metal production has traditionally been a cyclical industry. 1977 in the base metals industry has highlighted that fact with a steady decline in the market place for base metals. Corporate aggregate planning is based on good forecasting and when changing conditions make that forecasting inaccurate, alternate analysis of schedules must be accomplished quickly. The computer is the only medium powerful enough to answer management's questions within an acceptable time frame. Worldwide communications networks now make it possible for the many multinational mining companies to arrive at coordinated corporate production plans based on similar basic data from several producing divisions. The Ontario Div. of Inco Metals Co., a unit of Inco Ltd., encompassed during 1977 14 producing mines, 2 nonproducing mines, 1 nonproducing open pit, 5 flotation mills, I smelter, 2 nickel refineries, 1 copper refinery, and an iron ore recovery plant. Several new mines are under development. Mine production approximates 63 500 tpd (70,000 stpd) from some 1000 workplaces. The need for longrange mine planning and scheduling is obvious and until recently has been satisfied by manual methods. However, while manual methods are often quite practical for a small number of mines, or for mines with relatively short lives, or for mines with only one mining method, the situation in the Ontario Div. is too complex and long-term to allow effective, timely planning by such methods. In 1967, a year after the first computer was installed in the division, work was begun on the computerization of the more than 30,000 borehole logs kept in the mines exploration files with a view to speeding up the assessment of mineral resources. Also in 1967 one of the first substantial systems developed on the main business systems computer was the monthly scheduling of development and production for all mines. This system encompassed tons productions per workplace, feet development per workplace, auxiliary and service activities and the requisite labor for each of these. These two dates are mentioned to show that concurrently with the acquisition of computers in the division there was an early understanding of the importance of automating mine scheduling and planning and of the potential for effective and useful computerization of such activities. In 1970, a pilot program was developed in one of the mines containing a large number of workplaces (350) to schedule the production on a network basis. Varying degrees of interest were shown by the individual mine engineers based on the complexity of the production planning problem at each mine. In an evolutionary process, mines were added to the system as its value became obvious in terms of time saving, flexibility, and accuracy. In 1975, the central mine engineering department decided that the system should be extended to all mines so that a complete division-wide long-range scheduling system would be available upon which to base development and production planning. This system would use basic ore data, allow the addition of scheduling commands, and calculate a schedule for the life of the mine. Many reports could be produced for each mine and all-mine summaries would also be available. The significance of the system can be stated in one phrase-speed, accuracy, and flexibility. Whereas in the past a long-range all mines schedule might have been done once a year, taking from two to three months, now it can be done in a day. The chief mines engineer can incorporate changes in input data and external constraints and call for a "new look" at the long-range schedule to assist him and mines production management in their decision-making processes. Using previous manual methods this could not be done quickly enough to be useful.

Jan 1, 1979

By David Newman

Multiple seam underground coal mining is ubiquitous in Appalachia. Many coal properties have from two to ten or more economically mineable coal seams. Because of the ability to penetrate 600-feet to 1,000-feet or deeper into the mountainside leaving panels of web pillars separated by barrier pillars, highwall mining is a hybrid between surface and underground mining. As a result, many of the ground control problems commonly associated with multiple seam underground mining exist with multiple seam highwall mining. These include: i) multiple seam interaction between web and barrier pillars in superjacent mines, ii) subsidence and caving propagating to overlying seams and mines, iii) pooled water and the potential for inundation resulting from a breakthrough between an active highwall mine and abandoned underground mines in the same or superjacent seams, iv) the presence of overlying or underlying mine workings where pillar columnization in the active mine is not possible, and v) the question of whether to mine ?top-down? or ?bottom-up.? Case histories are presented from southeast Ohio where the Middle Kittanning No. 6 and Lower Kittanning No. 5 seams are successfully highwall mined with 20-feet to 40-feet of largely shale interburden. A highwall miner was caught in a highwall collapse in the Middle Kittanning No. 6 seam when it was overmining auger workings in the Lower Kittanning No. 5 seam. Multiple seam interaction caused by the overmining transferred overburden stress onto the Lower Kittanning No. 5 seam. The overburden concentrated through web pillars initiated auger web pillar failure, resulting in roof collapse and subsidence in the Lower Kittanning No. 5 seam that propagated up to the Middle Kittanning No. 6 seam. A second case history involves multiple seam highwall mining in southeast Kentucky. The A3 Rider, A3, B2, and C1 seams are being highwall mined around abandoned underground mines in the A3 and B2 seams and augering in the A3 Rider. Because of spoil storage constraints for the surface contour mines, the highwall miner follows the active pits in each seam so a standard sequence of ?top-down? or ?bottom-up mining does not exist.

Jan 1, 2009

By G. Brooker

The back-filling operation at Olympic Dam mine supports a 9.8 million tonne per year (Mtla) underground Longhole Open Stoping operation. It involves a combination of Cemented Aggregate Fill (CAF), Surface Rockfill and Underground Rockfill. The fill material is introduced from the surface via bore-holes into the top of the stopes. Due to the deleterious effects of the dust and the thickness of the atmosphere in the stope it is not possible to view the filling process. The need for a means to measure the filling process is driven by the stopes, which have both rock and CAF fill placed in them. The large volumes and high relative cost of CAF makes the minimization of CAF fill a business priority. Incorrect filling can lead to the sterilization of ore reserve. The use of millimeter wave radar to view through the haze to give real-time data on the relative positions of the different fill masses is being developed as an in-stope fill control device. This paper reviews the salient points of the technology and its potential use in the back-filling operation at Olympic Dam. The broader potential of this technology for use in the mining industry by 'seeing' through water and dust laden environments such as that found in stopes and ore passes is discussed.

Jan 1, 2001

Last year in the US alone, about 425 Mt (468 million st) of minerals and coal were beneficiated by froth flotation. This number indicates that from 1983 there was a 10% increase in tonnage of min¬erals and coal beneficiated by the indus¬try. A significant improvement was seen in the tonnage processed by the nonferrous minerals and coal industries. BP Minerals America installed 85 m; (3000 cu ft) flotation cells at the Bing¬ham Canyon mine and concentrator. The new flotation circuit has fewer than 100 cells compared to 2000 flotation cells used in the old plant (Mining Engi¬neering, November 1988). Column flotation use on a commer¬cial scale continues to expand as seen from the interest expressed at the Col¬umn Flotation Symposium (Column Flotation '88). The Magma Copper Co., San Manuel Division replaced all con¬ventional cells with 1.8 x 12 m (6 x 40 ft) column flotation cells for copper con¬centrate cleaning. Also, 1220 mm and 760 mm-diam (48 in. and 30 in.-diam) column cells are operating at the plant in the molybdenum circuit. A commercial Diester Flotaire col¬umn cell for fine coal recovery was installed at the United Coal Wellmore No. 20 plant. The 36.8 m3 (1300 cu ft) cell recovers 13.6 to 18 t/h (15 to 20 stph) of -590 gm (-28 mesh) coal. A similar unit has been installed at Tanoma Mining Co. in Pennsylvania. Various modifications of the column cells are being designed around the world. Jameson (Mining and Metal¬lurgy, 1988) described a new concept whereby the feed and air stream mixture is discharged into a cylindrical column of about 1.2 m (4 ft) height. Recovery and grade of nonferrous minerals have been reported to be better than that in a four-stage conventional flotation clean¬ing circuit. Flotation reagents American Cyanamid and Dow Chemical continued development of a new generation of sulfide collectors. A general feeling is development of new sulfide collectors has not kept up with flotation technology. Additionally, joint efforts between industry and chemical suppliers will likely be necessary to realize the economic benefits of the new technologies, since new chemistries respond differently compared to the conventional collectors. Flocculant development in recent years has been evolutionary rather than revolutionary. Rothenborg reported on development of a new flocculant family (a hydroxymated polyacrylamide desig¬nated S-6703) that has shown consider¬able promise in red mud clarification. Plant testing showed that this new floc¬culant could replace starch and poly¬acrylate and provide significantly higher overflow clarity. Barol Kami (Siirak) and Cleveland¬Cliffs (Hancock) reported development of an amphoteric apatite collector (ATRAC 873) that was used in Tilden's silica flotation process to increase apatite rejection. The collector was engineered for the particular flotation conditions in the complex Tilden process. Significant plant testing with ATRAC 873 showed that this reagent gave significantly in¬creased apatite rejection without any effect on silica flotation effectiveness or selectivity. Electrostatic separation Electrostatic separation is now em¬ployed in the precious metals mining industry to recover gold and silver grills from crushed slag. The installation at Paradise Peak has prompted other op¬erators to consider this application. In another development, attractive potentials for treating very fine minerals (-45 µm or -325 mesh) are being devel¬oped by Advanced Energy Dynamics and by the Department of Energy. Demonstration tests using triboelectric charging/electrostatic separation have been successful on a variety of minerals as well as coal. Magnetic separation Developments in magnetic separa¬tion have transpired on a production scale. Superconducting, high gradient magnetic separation has gained accep¬tance with the successful startup of a second unit treating kaolin at J.M. Huber Corp. This liquid-helium-cooled mag¬net generates 2.0 tesla in a 3-m-diam (120-in.-diam) bore with no power con¬sumption. Wet, high-intensity magnetic separation has been applied to sulfide mineral separations both domestically and abroad. These continuous type of separators are effective in removing residual chalcopyrite and sphalerite from other base metal sulfide concentrates. Separators using high energy rare earth permanent magnets are continu¬ally increasing. Now offered as both drum and roll type, these units are be¬coming a staple in the processing of industrial minerals. Tests using rare earth magnets strategically placed on a spiral concentrator have demonstrated the enhanced recovery of heavy miner¬als such as ilmenite. Classification Although no major technology break¬throughs in classification appear immi¬nent, there is an increasing need for more efficient and cost-effective meth¬ods to make size separations. It is be¬coming more apparent that mineral concentration methods will be more common at very fine sizes, say below 50

Jan 1, 1989

By Cahit Helvaci, Robert B. Kistler

Borates are defined as ' 'salts or esters of boric acid; a compound containing the radical B203" (Bates and Jackson, 1987). Borates are defined by industry as any compound that contains or supplies boric oxide. A large number of minerals contain boric oxide, but the three that are the most important from a worldwide commercial standpoint are: borax, ulexite, and colemanite. These are produced in a limited number of countries (Fig. 1), dominated by the United States and Turkey, which together furnish about 90% of the world's borate supplies (Lyday, 1991). Production in the United States originates in the Mojave Desert of California; borax and kernite are mined by US Borax from its large deposit at Boron. Borate containing brines are pumped from Searles Lake by North American Chemical Co., and a limited amount of colemanite is mined by Newport Mineral Ventures from Death Valley. Turkish production is controlled by Etibank, the national mining enterprise, which supplies most of the commercially traded ulexite and colemanite from mines in the Bigadic and Emet Districts, plus borax from the huge deposit at Kirka. Borate minerals have been employed in a wide range of uses for many centuries, dating from at least the 8th century when they were used primarily as a flux for assaying and refining gold and silver. Their valuable properties and relative rarity soon stimulated international trade in borates; Marco Polo claimed to have trans- ported Chinese borate minerals from Tibet to Europe, and his home port of Venice was the center for borate imports and use throughout the Middle Ages (Travis and Cocks, 1984). Borates were traded at relatively high prices for highly specialized applications into the late years of the 19th century. At that time they were being used for medicines, food preservatives, ceramic glazes, and in expanded applications as metal fluxes. It was in that era that borax was discovered in Clear Lake, CA, and more significantly, the playa deposits of western Nevada were found and exploited by F.M. "Borax" Smith and others. Research and development by Smith's company began the evolution of borates from a high priced commodity with a few specialized uses to the relatively low priced chemical raw material used in large tonnages on a worldwide scale today. Borates are often defined and sold by their boric oxide or B,03 content, and most statistical data are listed in tons of B203. Of the products sold by the industry, borax pentahydrate or 5 mol and boric acid are the most commonly traded commodities. Boric acid plants are operated by all of the major borate producers. Glass fiber insulation is the major end use in the United States followed by textile glass fiber and borosilicate glass, detergents, and ceramics. Detergent usage continues to be a major end use in Europe.

Jan 1, 1994