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By James L. Withiam, P. C. Kelsall

The manuscript of this paper was not available for publication when the Proceedings went to press. Should the authors elect, they may distribute copies at the time of the Symposium.

Jan 1, 1986

By R. A. Pimentel

Complying with reduced dust standards (i.e., less than 2.0 mg/m3) due to quartz levels that exceed 5 percent is presently a critical problem for many continuous mining sections. Results are presented of research which was performed to determine the factors causing high levels of respirable quartz dust and to identify the major contributors to operator exposure. It was found that the significant sources of quartz dust are the drilling of the roof and the mining of the roof, floor and rock bands. Both the miner and the bolter may be on a reduced standard, but compliance is easiest to achieve on the bolter for which improvements in maintenance and operator practices are usually sufficient. At the miner, the problem is more elusive. Research continues to identify operating and mining practices that contribute to the exposure..

Jan 1, 1985

By P. Zhu

The leaching behavior of copper powders recovered from waste printed circuit boards (WPCBs) was investigated using electrogenerated chlorine and aeration in a sulfuric acid solution with added NaCl and CuSO4. Various parameters were studied to understand the mechanism of the copper leaching. When the current density increased from 0 to 0.1 A/cm2, the temperature from 30 to 60° C, agitation speed from 100 to 400 rpm, and the size ranged from below 75 to 150 µm, the leaching ratios of copper powders increased. The leaching kinetics were analyzed using a shrinking core model: 1-(1-X)1/3 = kt, and the leaching process was chemically controlled with an activation energy of 14.7 kJ/mol due to Cl- ion catalysis. The ratios of [Cu+]/[Cu2+] at various temperatures (30, 40, 50, 60 and 70° C) showed a periodic variation with the increasing of the leaching time. The redox potentials of the leaching solution and copper leaching ratios in different conditions were measured. The result indicates that dissolved oxygen achieved the dissolution of coppers and electrogenerated chlorine can promote the dissolution of copper powders and improve the reaction rate of kinetics in the presence of oxygen.

According to the Balandin's (1) "multiplet theory of catalysis", adsorption can occur only if atoms of the reactant molecules are congruent with surface atoms of the catalyst. Such a condition calls for certain definite geometrical relationships between the reactant molecules and the atoms at the surface of the catalyst. If such a match or geometrical 'fit' is not provided, the surface reaction will not take place. An appropriate analogy to this may be the lock and key theory that enzymes should fit a substrate just as a key fits a lock. Similar geometrical considerations in adsorption studies were made in connection with the flotation of minerals. Gaudin(2) and Gaudin and Preller (3) proposed that if the dimensions of collector ions are in registry with the mineral lattice, an ordered layer of adsorbed species is formed. They explained that the structural fit is one reason for good flotation of galena with xanthate. In another study, Bachmann (4) attributed the selective flotation of KC1 from NaCl with amine to the fact that the lattice parameter of the amine collector is closer to that of KC1. Schubert(5) investigated the flotation of various nonmetallic minerals with amine and pyridine, and related the dimensions of the collector ions with the anion distances of the mineral surface. He concluded that good flotation is obtained when the tolerance is within 20%. The geometrical theory has also been used by Groszek (6) to explain the preferential adsorption of n-paraffin onto the basal plane of graphite. The geometrical theory has thus been found useful in explaining adsorptive properties of an adsorbate relative to the substrate structure. The purpose of the present work is to examine the possibilities of a geometrical fit between sodium dodecyl sulfate and Cu(OH)2 surface, and to construct a crystallographic model of the surface compound.

Jan 1, 1974

By Kirk Carlton

This paper deals with a group of subjects so familiar to all of us that we might question the need for discussion. Even so, nearly every day's business turns up expensive examples of differences in understanding, misdirected assumptions and incomplete technical purchase documents. As our international activities increase, so do these problem areas. Their expense in both money and embarrassment gives rise to this attempt to focus a little extra attention on technical criteria and specifications. The two terms ?criteria? and "specifications" are, we believe, worth separating with respect to meaning. They should not be used interchangeably, although they often are. Criteria are by definition "standards for judging", whereas specifications are "enumerations of particulars". In relation to plant or project engineering, the criteria are the general rules and data which apply to the whole project and the specifications are the further listing of detailed requirements for specific contractual items or pieces of equipment. We'll look a little more closely at specifications after we give another minute or two to this "criteria" subject,

Jan 1, 1973

By Douglas F. Stevenson

Your committee doesn't assign any easy topics to us speakers. How do you define "successful" in what is essentially a losing game? I am reminded of the fellow who returned from a one-week vacation in Las Vegas, and proudly stated, "I only lost $150." To him, that was "success." I am afraid that workers' compensation is a losing game for employers, too, and success has to be defined in terms of how much or how little is lost. We have no chance of producing a profit for our employer. We will narrow down to some suggestions about conducting a workers' compensation program at the plant level, but first I want to discuss the general legal, social and legislative climate in which your plant program operates. Workers' compensation is a statutory program with its general parameters established by the legislature. These parameters are then amplified by the boards and commissions established to administer workers' compensation. What influences the legislature and the boards and commissions as they establish the framework in which we must function?

Jan 1, 1986

By Heriban Soto

Primary amines are strong collectors of apatites and they can selectively float sedimentary phosphates from calcareous ores. However, secondary and tertiary amines and tri-methyl ammonium salts were ineffective. The use of kerosene reduces the collector requirements because hydrocarbon is coadsorbed along with the amine on the mineral surface. The heats of reaction of aminium ions with such anions as phosphate, carbonate and sulfate, were measured in a microcalorimeter and discussed in terms of the solubility of the precipitates formed and their relationship with the adsorption mechanism of primary amines on phosphate minerals. Experimental evidence supports a view that primary amines are adsorbed through chemical interaction between the aminium and phosphate ions at the mineral surface.

Jan 1, 1984

By M. C. Stuttle

MDL Rock Lasers has undertaken successful mapping trials of abandoned mine workings using its underground cavity scanning system. The work was being performed for Kalgoorlie Consolidated Gold Mines (KCGM), Australia's largest gold producer. MDL Rock Lasers supplies underground surveying systems to the mining and quarrying industry KCGM's Fimiston Super Pit, located in Kalgoorlie, Western Australia, is Australia's largest open-pit gold operation. Fimiston's final pit design is expected to be 3.7 km (2.3 miles) long, 1.5 km (0.9-miles ) wide and 540 m (1,770 ft) deep. During the early days of Australian mining, underground operations were labor intensive. Mining was selective and generally narrow stopes were mostly backfilled. Improved processing technology and mine mechanization during the 1970s and 1980s has permitted larger scale operations to adopt less selective underground-stope operations. The "super pit" concept was a logical step for mining companies working toward economies of scale. However, the industry recognized that there was no precedent for excavating a 500-m- (1,640-ft-) deep open pit through ground previously affected by old workings. To appreciate the geotechnical challenge facing KCGM, it is necessary to consider that under the pro¬posed area at the open pit, stoping reached a level of 1 km (0.6 miles) and was supported by more than 2,000 km (1,240 miles) of development headings. The company was fortunate because plans were available for the Golden Mile underground operations. The existing plans were interpreted by the mine's geotechnical team and computer models were constructed of the underground workings. These models can be imported into three-dimensional mine planning packages, such as the Vulcan's Unix-based software, Envisage, to assist analysis and design. This prior knowledge of the workings provided the focus for investigating and confirming ground conditions using probe drilling. After several iterations of drilling, followed by detailed analysis, several decisions were made relating to the nature of the ground and the mining approach to be taken. It was recognized that the stope models were not perfect due to hu¬man error, lack of original survey information and progressive deterioration in ground conditions. It also became apparent that the sole reliance on probe drilling was inefficient in terms of time and quality of information. This was particularly true in complex areas where stopes are in close proximity. A major concern was the presence of open stopes (voids). In many cases, stopes consist of combinations of filled and void sections. The condition of pillars within these underground workings is extremely important. In time, pillars collapse and voids will propagate in upward and lateral directions. So systems needed to be developed that allowed rapid and accurate verification of ground conditions. KCGM was introduced to MDL Rock Lasers while investigating technology for underground mining. The two companies decided to use the C-ALS, MDL Rock Laser's underground laser, cavity scanning system, to improve the management of mining through affected ground. This system was to be used in conjunction with probe drilling and void mapping activities. A field test in one area of the Fimiston Mine verified the capability of the C-ALS system to quickly and efficiently assist in this decision making process. The C-ALS scanner features lightweight, carbon fi¬ber alignment rods from Measurement Devices Ltd.'s (MDL) Boretrak MKII. This is a borehole deviation system that stops the two axis measurement head rotating and lowers the system down a borehole. The scanner is deployed by a 110-mm (4.3-in.) borehole, up, down or sideways. The operator can then carry out vertical and horizontal plan section scans at any user specified ARC (an angular increment of 2°) or the distance between two points on the ARC (CHORD) increments. Windows '95 software enables the operator to control the cavity scanner remotely, surveying the area in real time. The system makes data quick and convenient.

Jan 1, 1999

By Marek Niec

Native sulfur deposits in Poland occur in Upper Miocene strata on the northern (platform) border of the Carpathian foredeep. Systematic exploration since 1953 has resulted in the discovery of seven stratifom-stratibound sulfur-bearing limestone deposits that together contain about 0.6 billion tons of demonstrated sulfur reserves and about 0.5 billion tons of inferred and hypothetical resources. One open pit and three Frasch mines are currently in operation; another is under construction and one has been abandoned. Total production is about five million tons per year from ore containing on the average about 25% sulfur. Field, isotope, and micropaleontological data indicate that the sulfur-bearing limestone was formed through the bacterial reduction of gypsum in the presence of methane discharged from source beds and traps in the Carpathian foredeep. Subsequent recrystallization of the sulfur-bearing limestone, tectonic activity, jointing, karstification, and partial leaching of the sulfur has transformed the sulfur deposits and has altered the thickness and content of the sulfur-bearing strata, and their porosity and permeability, affecting the productivity and water consumption of the sulfur wells. Caputerized borehole logging techniques and geostatistical reserve estimates are used in mine planning. Great environmental impact constrains the development of sulfur mines.

Jan 1, 1992

By G. F. Ayakwah

Point load strength (Is50) and slake durability (ID2) indices provide a measure of the strength and durability of rock fragments and are related to the alteration intensity and frictional resistance of the materials. Samples were collected from the rock piles, alteration scars and debris flows at the Questa mine with the purpose of examining relationships between Is50 and ID2, mineralogy, chemistry, weathering, hydrothermal alteration, and other geotechnical parameters. The Is50 from the various rock piles ranges from 0.6-8.2 MPa and the ID2 ranges from 80.9-99.5%. The Is50 and ID2 results indicate that the samples from the debris flows are stronger (average Is50= 4.0 MPa and ID2= 98.4%) than the rock-pile samples and that the alteration scar samples are weaker (average Is50 = 2.8 MPa and ID2 = 89.2%) than the rock-pile samples, but still most of these rocks are strong in terms of their Is50 and ID2. The Is50 decreases as the degree of alteration increases in some rock pile and alteration scar samples, but not in all. However, the majority of the rock fragments within the rock piles still indicate high strength, even after 25-40 years of weathering.

Jan 1, 2009

By Joseph M. Denk, Gary J. Wirth

This paper summarizes a three phase face ventilation study which was conducted from September 1989 through March 1990 to determine face area methane liberation patterns on two extended longwall sections. The coal seam being mined was considered gassy and the mine liberated an average of 14.4 million cubic feet per day (cfd) or 0.41 million cubic meters per day (cmd) of methane through the mine fans. The mine also used an extensive underground degasification program to recover up to 13.4 million cfd (0.38 million cmd) of methane. Data was collected while the longwall sections were mining from the beginning, middle and end of panel extraction to determine the relationship between the methane liberation and extent of longwall retreat. As expected, methane concentrations did increase from the headgate (intake) to the tailgate (return) side of the longwall face and peak concentrations were detected above the shearer as it passed a methanometer location during mining. There were significant differences in the methane liberations due to the location of the active face within the longwall panel. Results from this study could be used to determine a minimum design face air quantity for an extended longwall section operating under similar conditions.

Jan 1, 1991

By B. M. Flohr

Railroads are cost competitive with trucks for hauls greater than 500 miles - WRONG. Today I will tell you about many rail movements of less than 100 miles throughout the country. Rail is a short haul transportation alternative you must consider. Transportation today is the largest controllable cost in the total cost of production of goods. In fact it is the one cost area where aggressive management, using new tools, can achieve significant reductions. You can't control the price of metals in the world market, you can't control labor rates since they are tied to industry norms, and the price of raw materials are relatively insensitive to specific price reductions to your firm. Transportation is the one area where major savings are now being realized. Sample Movements First, I will give you several examples of short haul rail moves to make you a believer that they do exist. Then I will show you the reasons why railroads suddenly "like" short hauls.

Jan 1, 1986

By Jerry G. Rose

This paper addresses a process by which both the disposal and utilization of preparation plant coal refuse can be simultaneously accomplished with an attendant benefit of significantly increasing the percentage of extractable coal. A laboratory study is described in which coal refuse was successfully utilized as an aggregate in low cost concrete (coal-crete) mixes under simulated mine environments. Coal-crete specimens with compressive strengths of 14,000 kPa (2,000 psi) were consistently produced. A construction sequence and mining plans are offered for placing the low-cost coal-crete pillars in accessible areas in room-and-pillar mines so that a Substantial portion of the remaining coal pillars could be extracted. The method could be applicable in areas where mining procedures do not permit pillar extraction because of possible surface subsidence, roof problems, or other conditions. Possible structural difficulties with the coal-crete pillar support system are discussed. Using a discounted cash flow analysis, the economic feasibility of mining with the coal-crete pillar system is investigated. The cost of the coal-crete pillar system is compared to the cost of a mining system which would have less coal recovery. The analysis indicates that although at higher coal selling prices the coal-crete mining system may yield an acceptable rate of return, the alternative of leaving the coal pillars is more attractive at the present time.

Jan 1, 1977

By James R. Yancik

Economical and environmental pressures necessitates the recovery of the minus 0.6 mm x 0 coal generated by todays mining machines. This size fraction, dependent on the type of production unit, maintenance of the production unit, and the Hardgrove Grindability Index, can be a substantial portion of the Preparation Plant feed. Historically, dewatering of the collected 0.6 mm x 0 product has often been rather expensive and marginal with respect to surface moisture reduction. The Freeman United Crown II Preparation Plant more than adequately demonstrates that the continuous scroll type centrifuge can dewater 0.6 mm x 0 coal to acceptable surface moisture levels.

Jan 1, 1981

By Lancelot E. Kun

The high-rate floc blanket clarification process developed by the Anglo American Corporation of South Africa is capable of continuously clarifying gold and uranium pregnant solutions containing 200-2500 mg/L suspended solids to below 25 mg/L solids at an average rising velocity of 8 m/h at the low process cost of R0,001-0,002 per ton of liquid treated. Overall process cost savings are mainly due to increased polishing filtration cycle times.

Jan 1, 1984

By A. B. Cecala

The US Bureau of Mines has designed and evaluated total mill ventilation systems (TMVS) at two mineral-processing operations. Both systems have proven proficient at cost-effectively reducing respirable dust levels throughout the mills. An 11.8-m3/sec (25,000-cfm) system installed at a clay-processing mill provided about 10 air changes per hour(acph). This system reduced respirable dust concentrations by about 40% throughout the mill building. The second evaluation was performed at a silica sand operation. Tests were performed with 23.6 and 47.2 m3/sec(50,000 and 100,000 cfm) of ventilation to the mill building, corresponding to 17 and 34 acph. Average mill-wide respirable dust reductions were 36% and 64%, respectively. This work was done to determine general guidelines and design criteria for operations that may be interested in implementing TMVS. TMVS should be designed to draw clean make-up air in near the base of the mill. This air provides general purging and may clear some dust-laden areas throughout the mill structure. It is discharged at or near the top of the structure. Without the TMVS, dust can exit the building through open doors, windows, etc. and contaminate outside plant workers. This dust can also be recirculated back into the mill building causing additional contamination problems. TMVS is not a stand-alone system. It is a supplemental technique to assist other localized dust control systems (Mody et al.,1987).

Jan 1, 1995

By G. V. Henderson

Limestone and Dolomite quarries located near Salto-De-Pirapora, Arroia Grande Gaucho, Conde Francisco and Candioita probably represent the closest, major sources of high quality lime and cement grade carbonate rocks to the major population center of Sao Paulo Brazil. The nearest major city to most of the limestone - dolomite sources is Sorocaba and Palma. All of the mining properties visited during this study are located in the state of Rio Grande Do Sul at approximately -32 degrees south latitude and -52 degrees west longitude, southwest of the major port city of Porto Alegre.

Jan 1, 1981

By George W. Leney

The iron ore industry might justifiably claim to have originated the science of geophysical prospecting. Their use of geophysical methods was probably the first application of these scientific techniques to the search for economic materials although the exact origin is undoubtedly lost in the unrecorded observations of. some prospector experimenting with compasses or bits of lodestone. Since 1879 when Thalen published "On the Examination of Iron Ore Deposits by Magnetic Measurements" these methods have been a standard supplement to other prospecting techniques. However, many of the great ore bodies of the Precambrian iron ranges were not particularly suitable for geophysical work. The ores were oxidized and enriched through leaching of silica so that they were nearly non-magnetic and other physical properties which distinguished them from the wall rocks were largely destroyed. With the gradual exhaustion of these high grade direct shipping ores, and ores that could be beneficiated by simple means, the iron ore industry turned initially toward the importation of similar high grade foreign ores. At the same time, new processes for concentrating lower grade materials were being developed and older ones improved upon. These concentrates' when pelletized produced such important savings in blast furnace hot metal costs that they now command a premium in the iron ore market and have weakened the competitive position of the remaining high grade ores. The ore bodies now being sought are usually unoxidized and frequently they are also metamorphosed.

Jan 1, 1965

By Dave G. Osborne

With the growing exportation of coal from North America to the Pacific Rim countries and Europe, has come an increasing awareness of the need to determine economically optimized amounts of incombustibles (ash and moisture contents) for the shipped product. Despite the fact that demand bas caused a steady improvement in selling price, particularly for thermal coals, growing production and transportation costs have compelled producers to keep a sharp eye open for ways and means of minimizing the latter since this probably represents the greatest single potential for making savings. Consequently the Coal Industry has become acutely aware of the economic ramifications of eliminating moisture in particular, thereby producing further saving in the cost of transportation of product from the mine to the consumer. There is, however, a lower limit to which dewatering or drying can be taken and this relates to dustiness which is a function of the characteristics of the coal and the methods used for handling and storage during trans-shipment. Overdrying can lead to serious dust losses and difficulties in handling particularly if the coal contains a large proportion of fines. The ways and means for achieving this "happy medium" of optimization in moisture removal are seemingly undergoing gradual modification largely assisted by the following factors. a) Improvement in effectiveness of coal dewatering and drying equipment. b) Improvement in operational availability and utilization of the equipment. c) The development of surfactants, polymer flocculants and other agents which in many cases can be almost tailor made to suit specific applications.

Jan 1, 1982

By K. J. Reid

With the current trends of increasing costs and decreasing head grades the mineral industry is no longer operating in very high profit areas and has been forced to pay greater attention to the application of modern technology. Although here are many technological advances to the credit of the industry in recent years there are still many processes being operated in the traditional manner and still many areas awaiting the application of methods which have been proven in other industries. Compared with the chemical industry the mineral industry is seriously ageing in the general areas of process analysis and process control, more so than can be justified by the complications arising from having to deal with particulate systems with properties far different from ideal, or even non-ideal, liquid systems. One area in which there has been a remarkable lack of application in the Mineral industry is that of analog computation and the authors feel that there is considerable scope for the use of the analog computer in studying mineral industry processes. The paper outlines the basic principles and features of the analog computer and describes its role as a simulation tool in some engineering and mineral processing systems.

Jan 1, 1972