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By G. J. Hartman

The Fort Cady in situ borate mining project involves recovery of boron from a mineral deposit located over 1400 feet below the surface. The resource recovery method is being developed using in situ mining technology employing weak acid solution injected directly into the ore body. As the acid contacts the calcium based ore (primarily natural colemanite), the contained borate values are digested as boric acid. This boric acid solution is then pumped to the surface by use of submersible pumps. At the surface the borate values are recovered as a finely divided solid white powder after a series of chemical reactions and precipitations resulting in the production of calcium borate. The refined product is then sold under the trade name CADYCAL 100.TM All environmental permits for up to a production rate of 90,000 tons per year have been obtained. These permits required an Environmental Impact study (EIS) for federal lands and an Environmental Impact Report (EIR) for the private portion of the property. Regulatory permitting required over 5 years to obtain all the various authorizations for this project. The ore body has an average thickness of 118 feet extending over 273 acres. At a production rate of 90,000 tons per year with only a 70 percent resource recovery allowance, in place reserves are sufficient to sustain production for over one hundred years.

Jan 1, 1997

By Robert E. Lovett

The truly educated man is better prepared to meet the challenge of the times. This challenge can be either beneficial or harmful depending upon one s orientation, Certainly man can no longer continue in the way of his father or even in the manner of his own previous experience as he seeks self-fulfillment, unless he is willing to sacrifice inner integrity--unless he is willing to compromise self-determination and self-expression. He must make a choice as society moves rapidly into high gear in the areas of automation and cybernetics. Industry, a unit of society, has a high stake in meeting this challenge, The better prepared and more mature its personnel, the better the end result as it attempts to meet the challenge. It therefore has a vital concern in proper training of such personnel, that their contribution will be of maximum quality. The specialized training required demands a broad liberal arts background which gives the individual a wider perspective upon which to base judgment. This greatly aids his development as he enters graduate school or goes directly into industry. In either case, his value to industry is enhanced. It would seem that the small liberal arts college provides the best environment for such a program, Consideration of several factors will, I hope, throw some light on the severity of the problem.

Jan 1, 1966

By Su Yang, Pang Shun, Xiaoding Xu, Guodong Yang, Hengfeng Liu, Meng Wu, Yuejin Zhou

By introducing the hydrochemical damage variable of coal gangue granular material, this paper analyzed the evolution law of gangue mechanical parameters with hydrochemical damage. By constructing a gangue damage model considering multifield coupling, the damage mechanism of gangue under multi-field coupling was revealed from the microscopical aspect, and the influence law of gangue damage mechanism on the dissolution of toxic substances under multi-field coupling was obtained: the conditions of Test 1 have the greatest influence on the porosity of coal gangue, and the damage of coal gangue is the greatest. Cu, Zn, Cd, and Pb are more easily leached under acidic conditions. The coupling effect of seepage, temperature, and chemical field can promote the formation of secondary voids, change the voids, and form migration paths in coal gangue. The kinetic model of toxic leaching of coal gangue under multi-field coupling can be well characterized by Elovich equation. The release mechanism of heavy metals is mainly manifested as delayed diffusion or dissolution in the early stage, diffusion and dissolution in the middle stage, and depletion in the late stage.

Nov 23, 2023

By J. H. Meza Viveros

This paper describes some actual parameters and technologies used at Mexicana de Cobre Smelter, and the principal design parameters and new technologies which wiil be used with the smelter expansion project, in order to increase the production capacity of anode copper from 180 000 mtpy to 300 000 mtpy. Likewise its describe some parallel projects under construction also in the smelter plant.

Jan 1, 1997

By James P. Connell

HISTORICAL BACKGROUND The American Concrete Institute defines shotcrete as "mortar or concrete conveyed through a hose and pneumatically projected at high velocity onto a surface." This definition thus includes what is traditionally known as gunite, which is a pneumatically applied mortar. In mining practice, the term shotcrete is restricted to pneumatically applied concrete, and this differentiation will be used in this chapter. In 1914, following the invention of the mortar gun in 1907, then chief engineer of the US Bureau of Mines (USBM) George Rice developed the gunite process for underground test work at the USBM facility at Bruceton, PA. After World War I, gunite was used extensively in American mines and was also utilized for underground civil works such as the San Jacinto tunnel in California. The greatest development was in Europe where, as early as 1911, gunite was successfully used as an overlay for deteriorated tunnel linings. In 1951, the Swiss firm Aliva developed a pneumatic gun capable of handling coarse aggregate, thus making possible the first use of shotcrete at the Maggia hydropower development. Initially, shotcrete was used to reduce manpower requirements for forming and placing conventional concrete. However, by 1954 Sonderegger was reporting that the structural advantages of shotcrete were derived from its flexibility and from the fact that it could be applied almost immediately after the opening had been made. The incorporation of wire mesh into the shotcrete led to the new Austrian tunnel method or NATM. The use of shotcrete in American mines has been implemented more recently. This delay seems to be due to previously unsuccessful experiences with gunite as a structural material and to the US reliance on wood or steel supports in main-line haulageways. The long experience with the apparently more substantial rigid supports led mine operators to be reluctant to accept the new and seemingly unrealistic lighter shotcrete support. APPLICATION REQUIREMENTS Shotcrete is a relatively new material for use in underground support systems. Consequently, experienced miners are not always available who are capable of applying the material effectively. Shotcrete, particularly in the small cross sections typical of mine shafts or haulageways, is applied in cramped quarters under less than ideal conditions. Adequate lighting should be made available. The surface should be clean and free of running or dripping water. It may be necessary to collect flowing water in plastic pipes or water collection devices. Any dry cement dust from previous shotcrete applications should be washed from the surface in order to assure a good bond. The US Bureau of Reclamation (USBR) while shooting test panels at the Cunningham tunnel in 1974, found that experienced shotcrete operators were able to obtain up to three times greater compressive strengths than were obtained by unskilled operators using the same equipment and shotcrete mix. ENVIRONMENTAL AND SAFETY REQUIREMENTS Since sodium and potassium hydroxide, as well as other moderately toxic compounds, are often contained in shotcrete (particularly where accelerators are used), safety precautions must be taken to prevent skin and respiratory irritation. Nozzlemen and helpers are required to wear gloves, protective clothing, and ventilation hoods with a filtered air supply. Respirators approved by USBM, equipped with chemical filters that will not pass the caustic mists, may be permitted in lieu of hoods if goggles or safety glasses are worn. Protective ointments are available to reduce skin irritation. All air and shotcrete feed hoses should be equipped with safety-type couplings and secured with safety chains at each coupling to prevent whipping in the event of a hose or coupling failure. Some environmental effects can take place down-stream from the development face being supported. The accelerator compounds, as well as the portland cement used in the shotcrete, will be found in the rebound material which falls to the invert of the heading. Since these compounds may be leached from the rebound material and carried by the drainage system, it may be necessary to install neutralizing or other water treatment facilities. Investigations may find that the final reaction with other compounds being leached from the mining operations may result in a more or less environmentally acceptable end product. USES OF SHOTCRETE General Uses Shotcrete, as a combination of cement, aggregate, and accelerator, is utilized for underground openings such as shafts, adits, haulageways, and service chambers for the following general purposes : (1) primary sup¬port; (2) final lining; (3) protective covering for excavated surfaces that are altered when exposed to air (the protective covering may be of a temporary or final nature); (4) protective covering for steel or wooden supports, rockbolts and rockbolt plates, heads, nuts, and other mats, including wire fabric, used to prevent rock-falls; and (5) as a lagging material in place of timber, steel, or concrete between steel or wooden supports. These applications can be grouped into three general use categories: shotcrete used as a rock sealant, shotcrete used as a safety measure, and shotcrete used as a structural support. Use as a Rock Sealant Thin applications of shotcrete can reduce or prevent slaking of shales or other rocks that are altered when exposed to the wetting and drying cycles created by mine ventilation circuits. While shotcrete may be effective in preventing such rock alteration, at the present time it is not as economical or efficient as other commercial sealants. However, if the sealant property can be incorporated into the structural support capability, the added contribution is usually helpful. Thin applications are not usually sufficient if the alteration of the

Jan 1, 1982

By M. E. Buzon, M. E. Gunter

Talc has been the focus of recent civil litigation based on claims that asbestos minerals exist in talc deposits and therefore have caused asbestos-related diseases in those who have regularly used talc products. Such litigation, and ensuing confusion over the petrology and asbestos content of these deposits, challenges the talc mining industry in Montana and elsewhere in the world. The talc deposits in southwest Montana were formed by hydrothermal alteration of dolomitic marbles and are still actively mined. In general, talc formed by hydrothermal alteration of preexisting carbonate rocks is known to be nearly monomineralic and lacking in amphiboles. This paper includes data from analyses of representative ore samples from this mining region in southwest Montana. The results conclude that the presence of asbestos minerals — both amphiboles and chrysotile — is unlikely and that the ores are nearly monomineralic, as expected. Samples were characterized using a suite of analytical methods, namely, powder X-ray diffraction, X-ray fluorescence spectroscopy and electron microprobe analyses, which allowed us to determine the minerals present and the formation process. Our data and interpretations suggest that previous identification of asbestos minerals in these deposits is not accurate.

Jan 1, 2018

By M. E. Buzon, M. E. Gunter

Talc has been the focus of recent civil litigation based on claims that asbestos minerals exist in talc deposits and therefore have caused asbestos-related diseases in those who have regularly used talc products. Such litigation, and ensuing confusion over the petrology and asbestos content of these deposits, challenges the talc mining industry in Montana and elsewhere in the world. The talc deposits in southwest Montana were formed by hydrothermal alteration of dolomitic marbles and are still actively mined. In general, talc formed by hydrothermal alteration of preexisting carbonate rocks is known to be nearly monomineralic and lacking in amphiboles. This paper includes data from analyses of representative ore samples from this mining region in southwest Montana. The results conclude that the presence of asbestos minerals — both amphiboles and chrysotile — is unlikely and that the ores are nearly monomineralic, as expected. Samples were characterized using a suite of analytical methods, namely, powder X-ray diffraction, X-ray fluorescence spectroscopy and electron microprobe analyses, which allowed us to determine the minerals present and the formation process. Our data and interpretations suggest that previous identification of asbestos minerals in these deposits is not accurate.

Jan 1, 2017

1. Paper1?Identification and enumeration of asbestos fibers in the mining environment: mission and modification to the federal asbestos standard Arthur M. Langer Asbestos-related disease is increased with cumulative exposure (the concentration of asbestos in the air and duration of exposure). The maximum duration is assumed to be a working lifetime so federal agencies control cumulative exposure by limiting the airborne concentration of asbestos fibers equal to or greater than 5 lm in length. Air samples are collected in the environment of interest by entraining the airborne particulates including fibers on membrane filters and then counting the number of fibers using phase-contrast light microscopy. In addition to length, the fibers must have a length to width ratio of at least 3 to 1. This ratio is also referred to as the aspect ratio. Some counting strategies placed an upper limit on the fiber width restricting the counting to respirable fibers. Airborne asbestos is controlled by monitoring a sub-population of the airborne asbestos. No asbestos fibers shorter than 5 lm or fibers of any length having widths less than the resolution of the light optical method are counted. In the non-occupational environment, the Environmental Protection Agency requires the use of analytical transmission electron microscopy and fibers and counting fibers with lengths of 0.5 lm or greater and aspect ratios of 5 to 1 or greater are counted. The permissible exposure limit for asbestos has been reduced by more than 120-fold since 1969, when the standard was 12 fiber/ml and the current monitoring methodology was developed. The manufacturing and mining worksites are regulated by two different federal agencies and the asbestos exposure limit was higher in the mining environment until recently (Mine Safety and Health Administration 30 CFR Part 56, 57, and 7, Federal Registry, February 29, 2008). Currently the permissible exposure limit (PEL) is the same in both types of workplace and it is 0.1 fibers per milliliter (fiber/ml) over an 8-h shift as a time-weighted average (TWA). A milliliter (ml) is equivalent to a cubic centimeter (cc) and sometimes this standard is reported as 0.1 f/cc. As the phase-contrast methodology was used to monitor lower exposures and environments, other fibrous mineral particulates were incorrectly characterized as asbestos. These occurred in talc deposits and taconite ores from the Eastern Mesabi Range.

Jan 1, 2008

By Terrence J. Stobbe

On the job injuries to the musculoskeletal system are probably the oldest of the industrial safety problems. Long before we had pinchpoints to guard, chemical vapors to ventilate, and noise to enclose, people were getting strains, sprains, and sore backs from their work activities. In spite of the age of the problem, it remains a long way from being solved. The past ten years have seen a significant commitment by the sci¬entific community to understanding the problem. Engineers, scientists, doctors, and epidemi¬ologists have been involved, and as a result, today we have a much better understanding of the problem. The first step in understanding a problem such as this is to explore its history and epidemiology. The research done by Chaffin (1977), Snook (1970), Ayoub (1978), the ILO (1962), and others, led NIOSH to publish its Work Practices Guide for Manual Lifting in 1981. The guide was based on research carried out in general industry, but subsequent research by Stobbe (1983) and Peters (1983) has suggested that the nature of the problems producing injuries in underground mining is the same as in general industry. The problems are more intense in the mining environment.

Jan 1, 1984

By Liming Yuan

To reduce fire hazards from spontaneous combustion of coal in longwall gob areas, a series of computational fluid dynamics (CFD) simulations were conducted by the National Institute for Occupational Safety and Health (NIOSH) to model the spontaneous heating of coal in longwall gob areas. The previous modeling results demonstrate that spontaneous heating of coal usually occurred behind the longwall shields and along the face with a bleeder ventilation system. Assuming a stationary longwall face, the spontaneous heating could turn to a spontaneous fire in several days for the most reactive coal under favorable conditions. When the longwall face advances, the spontaneous heating process will be significantly affected. In this study, the effect of longwall face advance on the spontaneous heating in the gob area is investigated using the CFD model developed in previous studies. One longwall panel with a bleeder ventilation system is simulated. The width of the panel is 300 m (984 ft), while the length of the panel is changed between 1,000 to 2,000 m (3,280 to 6,560 ft). The same permeability and porosity profiles are used for gobs with different lengths. The spontaneous heating first develops in the gob when the longwall face is stationary. Then, the face advances at a certain rate. The face advance is simulated as a series of discrete movements, and the effect of the face advance on the maximum temperature developed during the face stoppage is examined.

Jan 3, 2010

By W. L. Josey

The Stibnite Project is an open pit/cyanide heap leach gold property located in the Yellow Pine mining district of central Idaho. The gold ore is in an oxidized zone of an epithermal deposit which is associated with a fault system related to Tertiary igneous activity of the region. The faults transect a roof pendant of metamorphosed sediments within crystalline rocks of the Idaho Batholith. Seasonal mining is at a rate of 3900 mt/d (4300 st/d) of ore with a 2:l waste to ore ratio. Gold and silver are recovered through a process of cyanidation, carbon adsorption and desorption, and electrowinning. Disposal of the leached ore requires chlorination of the residual cyanide.

Jan 1, 1984

By J. Olsson

Introduction Stainless steel has by tradition been a common construction material for hydrometallurgy processes and the most common grades can be found amongst the ASTM 300-series, i.e. austenitic grades of type 304L, 316L and 317L. However, there are a number of new grades available today, which imply more cost effective solutions for those designing plants where good resistance to acids, containing the desired metal ions, often contaminated with chlorides and other halides, is the key issue. There are austenitic-ferritic or duplex grades having the same or even better corrosion resistance than the austenitic grades and approximately twice the strength, which enables design in thinner gauges, which in turn implies less weight and less cost. They have also excellent engineering properties, enabling fabrication of process equipment, machinery and different types of tanks. On top of that, they contain less nickel and molybdenum than their austenitic counterparts, which implies not only lower cost for alloying elements, but also a more stable price when considering the price fluctuations for these alloying elements during the last years. This paper describes briefly the family of duplex stainless steel and it presents a number of relevant corrosion tests where duplex grades have been compared with austenitic grades. The results have in several cases been verified by in-plant exposures in zinc and copper production plants. It also describes applications and experience of duplex grades within a variety of hydrometallurgy plants. Installations of highly alloyed austenitic grades will be described as well. The corrosion tests and service experience reported cover hydrometallurgical processes based on sulphuric acid.

Jan 1, 2007

By Quansheng Li

Large-scale coal mining will cause environmental problems such as aquifer damage, land excavation and occupation, soil erosion, vegetation damage, and regional landscape damage. The existing coal mine environmental restoration technology is relatively simple, and there is a lack of systematic research on environmental total factors. Based on the mechanism of coal mining damage and the laws of environmental natural succession, the concept of “coal environmental protection mining” is proposed, which combines damage reduction mining and environmental element system restoration. In accordance with the environmental protection principle of “source protection, process damage reduction, and systematic restoration,” a technical system of “coal environmental protection mining” is constructed for the two types of mining damage scenarios: underground mining and open-pit mining. In view of the damage characteristics of underground mining, source environmental protection technology based on optimization of mining process parameters, stability maintenance and damage reduction technology for overlying rock bearing arch shell structure, zoning and time-sharing treatment of surface cracks, and direct drainage irrigation technology for mine water have developed. In accordance with the damage characteristics caused by open-pit mining, land-saving and source reduction damage technology, near-natural stratigraphic reconstruction, topsoil improvement, and environmental storage and utilization technologies for seasonal precipitation have developed. By applying the technology in this paper, the maximum surface settlement value of 12401 working face in Shangwan coal mine was relatively reduced by 25%, the surface cracks have been adjusted from step-type cracks to dynamic small cracks, and since the technical implementation of the Shendong mining area in 2010, the vegetation coverage has increased loss and crushing decreased by 0.06 km2 every year, the environmental restoration period of the dump site was advanced by more than one year, and the vegetation coverage rate increased by 41.78% compared with the background value in the semi-arid area of the victory open-pit coal mine demonstration area. A surface reservoir with a water storage capacity of 400,000 cubic meters has been built, and the seasonal and graded utilization of mine water has been realized. An underground reservoir with a water storage capacity of 1.22 million square meters has been built in the Baorixiler open-pit coal mine.

Jun 25, 2024

By Timothy Batchler, Khaled Mohamed

Standing supports have been used in coal mines for decades to enhance roof support capability. Sometimes standing supports are used as a tool to resist the lateral movement of spalled ribs. Researchers from the National Institute for Occupational Safety and Health (NIOSH) are conducting a testing program for different types of standing supports (steel and timber) to investigate the effect of lateral loading on their vertical loading capacities and the factors affecting their lateral loading capacities. In this paper, the mine roof simulator (MRS), at the NIOSH Pittsburgh research facility, was used to determine the response of steel props to vertical and horizontal loadings. Finite element models (FEMs) were developed and verified using the tested steel props. To justify the testing program for testing standing supports with end-conditions of rock-like materials, the verified prop models were used to study the effect of a wide range of roof and floor materials (gray shale, shale, and claystone) on the critical buckling loads of the steel props. Also, several lateral loading scenarios were evaluated in which the steel props were laterally loaded at different heights. The critical buckling load for steel props setting up against a claystone roof and floor was found to be one-half of that shown by the MRS test where roof and floor platens are made of steel. Minimum prop performance was observed when the lateral load was applied at the mid-height of the steel prop, especially at small lateral displacement (less than 2 in).

Sep 10, 2022

By T. Murt, C. Oñate

In recent years, environmental considerations have played a prominent role in underground construction projects. The management and disposal of the muck produced by an EPB TBM is an important aspect of this topic. Soil conditioners with higher biodegradability and lower eco-toxicity have been specifically developed to comply with strict regulations in several countries around the world, with the goal of reducing the environmental impact of tunneling on soil, water, and living organisms. This paper highlights innovative sustainable soil conditioners and how they differ from traditional products. Additionally, environmental considerations for TBM projects around the world and in North America will be examined.

Dec 1, 2022

By Nilabjendu Ghosh, Satyendra Kumar Singh, Gautam Banerjee, Harshit Agrawal

High-production methods like longwall mining with hydraulic powered supports are necessary to increase underground coal production in India. Longwall mining had a mixed success record for Indian geo-mining conditions. In this paper, an analysis is presented to optimally design an array of chain pillars in multi-seam longwall mining panels in the deepest coal mine in India. The study found that a chain pillar of 80-m width and 195-m length is necessary for long-term stability without any reinforcement. It was also observed that an optimum chain pillar can be designed by providing suitable side reinforcement (side bolting) which will reduce the chain pillar dimensions to 55-m width and 160-m length. Optimum design of chain pillars will reduce the coal locked up in these chain pillars by ~ 77%. This will also reduce the gestation period of longwall mining panel development. This paper also evaluates the maximum tensile subsidence strain induced at the surface and finds that the values are within the safe working limit of 3 mm/m. Thus, this paper finds direct application in the design of future multi-seam retreating longwall mining panels in Indian geo-mining conditions.

By F. Calizaya, S. Bhattacharyya

"INTRODUCTION Mechanized underground mines often suffer from noise overexposure. Noise levels are usually above the Permissible Exposure Limit (PEL) where underground fans are used. Sound levels in active workings can reach 121 dB(A), especially when fans are not equipped with silencers. Use of silencers seldom ensure PEL for various reasons. Overexposure of noise induces permanent hearing loss among mine workers. Recent field studies by a NIOSH-funded research project at six coal and non-coal mines revalidated the findings. The University of Utah has undertaken laboratory studies to reduce fan noise at the source. A new silencer prototype with varying noise dampening material has been designed and tested. The silencer and an associated extension which can be repacked with different dampening materials were used in various configurations. Attempts were made to simulate field conditions where installations are quick and not perfect. The test results are presented here. NOISE IN UNDERGROUND MINES Noise induced hearing loss (NIHL) is a chronic problem in the mining industry. In spite of regulations being in place and elaborate hearing protection programs under way, hearing loss is prevalent among the mine workers (Bise, 2001). All production and support machinery in mining generate loud noise often beyond the approved exposure level. Researchers in the U.S. have identified auxiliary fans as one of the major sources of noise that can create noise exposure levels up to 121 dB(A), which is one of the highest in the mining operation (Bauer, 2006). Studies have demonstrated substantial reduction of noise level by using silencers. Adequate fan selection and proper utilization of silencers in auxiliary fans have great potential of abating the problem. In hard rock mines, auxiliary fans are used in blower configuration to ventilate development headings and large production stopes, and also to ventilate underground shops, crushers, conveyor transfer points, etc. Typical duct diameters in hard rock mines vary from 0.91 m to 1.21 m. Silencers are often omitted for cost reduction. In coal mines auxiliary fans are used in exhaust configuration with rigid ducts 0.61- 0.76 m in diameter (Hagood, 1982 and Moreby, 2009) to ventilate working faces in gate-roads and main entry developments. Sometimes, stone dusters are added at the discharge end to dust the roof, ribs and floor. AUXILIARY FANS AND SILENCERS Auxiliary fans are relatively smaller in size than the main fans and often have high rotational speeds (1800 -3000 rpm). Fans are selected based on pressure-quantity requirements and space restrictions only. Noise emissions are rarely considered during the selection stage. Installation of fans, ducts and other accessories is mainly based on best practices, which often do not include noise control. As a result, the operation of an auxiliary or local ventilation system normally produces excessive noise."

Jan 1, 2018

By J. R. Evans

Mining claims must have a discovery of a valuable mineral deposit to be valid. When required, a Federal government mineral examiner makes a determination of validity and recommendations thereof to authorized management officials. The examiner should show whether or not an existing mining operation, or a proposed operation have economic viability. This is accomplished through an analysis of legal entities, land status and use, geologic and mineralogic relationships, and mining, milling and processing techniques considered in an appropriate economic evaluation framework. A framework involves market and market entry studies, reserve analyses, all costs analysis, royalty buyouts, tax structure, discount rate of return, and escalation and risk factors. An income approach to value is then used by means of a simple or complex discounted cash flow (DCF) analysis to certify validity. Whether one claim is owned by a single miner, or hundreds of claims are owned by a large corporation, thorough, fair, consistent, and appropriate economic concepts should be applied by the mineral examiner.

Jan 1, 1993

The US Bureau of Mines' dictionary of mining terms defines productivity as "the efficiency with which economic resources (men, material, and machines) are employed to produce goods and services." Or, the relationship between the physical outputs and the physical inputs used to produce those outputs. As demand for mine materials dropped, mining companies and equipment manufacturers discovered that ratios between the inputs and the final products were disproportionate to the profits realized. Some companies are fighting for survival. The US, while still the most productive country in the world in absolute terms, is looking over its shoulder as other industrialized nations continue to exceed its yearly productive growth rate. According to John Belcher, Jr., of the American Productivity Center in Houston, TX, the US has seen a steady decrease in productivity growth since the mid-1960s. During the post World War II period, the US labor productivity growth rate was 3.2% annually. The slowdown began in 1965 and by the mid-1970s, the country's annual growth rate was 1%. By 1978, labor productivity growth ceased to gain at all and from 1978 to 1980 a 2% decline occurred. Solutions to the productivity decrease are increasing product prices or improving productivity. By increasing prices, though, the producer runs the risk of pricing himself out of the competitive market. To maintain an acceptable profit level, prices must increase proportionately higher than required to offset production cost increases, Belcher says. Many companies are turning to in-house productivity improvement programs as an answer to increased costs and declining profits. These programs are geared toward management commitment and employee awareness of what productivity means. Companies are finding ways of measuring productivity levels in financial reporting, budgeting, and planning. Organizational teams have been formed to coordinate activities and oversee product management, and improve productivity of materials and capital investments. This special issue of Mining Engineering examines productivity in the mining industry. First, there are articles about various, and different, factors that affect productivity in each of ME's five main readership areas - exploration, mining, processing, coal, and industrial minerals. There is also a look at mining industry productivity from the manufacturer's view. The next section of this special issue is devoted to some topics that affect all areas and sectors of mining: research, management practices, computers, maintenance, and energy management. Then follows case studies in exploration, coal, and iron and steel. These studies provide examples of practices and strategies used by companies and operations to boost productivity.

Jan 11, 1983

By C. Maltesh

Anionic conditioning of phosphate ores prior to fatty acid flotation is a very critical step that determines the eventual selectivity, recovery and hence the economics of the process. However the chemical mechanisms operating during this conditioning step are not established. Several studies have been conducted in the past to determine the mode of interaction of collectors with the phosphate fractions however these have been done on a laboratory scale using pure phosphate minerals. In order to test the relevance of the observed effects to plant practice in this work a comprehensive survey of plant practice was first conducted and then adsorption on flotation feed and francolite were studied under simulated plant conditions. Effects of conditioning energy and water chemistry as well as solids loading and fuel oil were determined. Most importantly, different adsorption mechanisms were found to be dominant under laboratory and plant conditions. In plant water, there was some physisorption of oleic acid on phosphate flotation feed and francolite in addition to chemisorption. However, in distilled water under laboratory conditions only chemisorption was detected. Fuel oil reduced the residual oleic acid in solution after adsorption, which explains the beneficial role of extender in phosphate flotation. The dissolved species in solution arising from the flotation feed or plant processing water are shown to clearly play a major role in determining the adsorption of oleic acid on the substrates. The study also specifically demonstrates the importance of conducting research tests under plant mixing conditions and plant water chemistry for the results to be useful commercially.

Jan 1, 1996