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By Adrian C. Dorenfeld

[Agitation and transport of slurries have been investigated intensively for the past twenty years. It has been shown (1) that slurries have the properties summarized in Figs. 1, 2, 3, 4, and S. For a detailed exposition the reader is referred to the above reference and the bibliography, which, in turn, have extensive references and bibliographies. An interesting problem with which the senior author has been concerned with is the scab up of power requirements for slurry agitators operating in the laminar region with pseudo plastic materials. Pulps of shaly ores, after various chemical reactions in aqueous leaching systems, are often difficult to settle and filter if agitation is violent. In these cases agitation must be at a minimum, yet prevent [tling] such as in copper uranium ores. This mild agitation is on the laminar region.]

Jan 1, 1967

By Inkap Choi

Asbestos is a broad term embracing a number of fibrous silicate minerals. These minerals look extremely fragile, yet their fibers have a tensile strength equal to that of piano wire. Chrysotile asbestos is the only mineral that can be woven into cloth, and its fibrous structure is, if anything, even more amazing than its remarkable ability to withstand heat. Because of its unique physical properties asbestos has achieved great industrial importance, and more than 3,000 current uses are known, ranging from use in the kitchen to use in space missiles. Because their minuscule fibers are eminently respirable, asbestos minerals have also found their way into the lungs of humans, where they apparently produce serious biological effects such as asbestosis and lung cancers. 1, 2,3 Because of both their usefulness and their hazardous properties, these minerals have attracted a good deal of attention from research workers during recent years. For example, the surface properties of asbestos minerals have been studied by many investigators. 4, 5, 6, 7, 8, 9 However, even for the important mineral chrysotile, the literature data are more or less conflicting. Pundsack4 measured a PZC (point of zero charge) of 10.1; Martinez and Zucker5 measured 11.8; Chwastiak reports 10.8-11.0; and Raddick measured three sepa-rate apparent PZCls at about pH 8.3, 10.0 and 10.9. More recently Trivedi8 reports 10.11. Naumann and Dresher9 have studied surface charge enhancement of chrysotile by metal ions, and describe how the mineral reacts with contaminantions. In the present paper, the mode of dissolution of magnesium and hydroxyl ion from asbestos minerals placed in water was studied by kinetic experiments involving rate at which these items leave the minerals. Also, some study was made of interaction between dissolved species.

Jan 1, 1972

By Robert E. Moore

Investigators have attempted to develop lime refractories on a scale for broad applications in the metal and ceramic industries for several decades. There was a flurry of activity in the early to mid-fifties but no commercial developments were forthcoming. The literature of that period yields little information on plant trials. A major factor suppressing past interest in lime has to have been the high success with the application of magnesic and dolomitic materials. These materials, usually tar-bonded or impregnated, have become the refractories success story of the past two decades, especially in BOF applications. It is safe to say that their development and application has essentially plateaued, and that work today is focussed on finding cheaper paths to produce MgO-based refractories. For example there are efforts underway to extract MgO from mineral magnesite and to combine natural dolomite with MgO1. Beginning in the late sixties, rather intensive research began on the development of CaO brick, especially in East and West Germany, in Poland, and other communist bloc satellites, 'and also in Italy and Spain. One speculates that the motivation was a regional shortage of good magnesia and dolomitic material. Of course, There has always existed the prospect of cost savings should it be possible to use raw limestone as the starting material. Quite a large literature has appeared treating of these developments which in the early seventies had already reached full plant scale trials and uses. Some of the directions followed in the research have led to novel methods of brick manufacture.

Jan 1, 1985

By R. Musu, J. A. E. Bell

P.T. Inco has constructed a smelter to produce 45 000 tonnes (49 500 tons) of nickel per year as a nickel matte from the lateritic ores of Sulawesi, Indonesia. The facilities include mines, five screening stations, two dryers, three novel reduction kilns, three electric furnaces, three top blown rotary converters, and associated infrastructure of port, towns and a hydroelectric generating station. The screening stations and converters are unique in the industry. The problems encountered in the construction and operation of this complex facility in remote Indonesia are described.

Jan 1, 1979

By A. B. Cecala

Two recent Bureau studies evaluated workers' dust exposures in automated pallet loading processes. The first study involved a Bureau designed dust control system using a push-pull ventilation technique. The unit was shown to reduce workers' dust exposures by 76% during pallet loading at a ground silica operation. A hydraulic lift table was used to automate the bag stacking process; this kept the loading height constant throughout the entire pallet loading cycle. The second study evaluated different commercial automated pallet loading systems. These systems automatically stack the bags onto pallets, shrink wrap the pallets, and deliver the pallets to a fork lift pickup location. Results from a ground silica evaluation site indicated respirable dust samples taken were below the Threshold Limit Value (TLV) as established by the Mine Safety and Health Administration (MSHA).

Jan 1, 1990

By J. Lorosch

Improvement of current leaching technology was found necessary when processing ores which are more difficult to leach because they generate highly viscous, air-rejective pulps. Cyanidation of these pulps has to run at low oxygen concentrations if the conventional aeration technique with compressed air is used. Since the dissolution rate of precious metals mainly depends on the concentration of dissolved oxygen in the pulp [1, 4, 5], the kinetics of the gold extraction become slow in such cases, which in turn often leads to a significant decrease in the overall gold output within the conventional leaching time of up to 48 hours.

Jan 1, 1988

By Roland Hoet, Jim Patilla, Nick Madison

Increasing conveyor capacity and reliability is a common goal for many underground mines. This task is especially challenging when you must work with existing structure, belt, etc. Meeting this challenge, The Pittsburgh & Midway Coal Mining Co. North River Mine switched from constant fill to actively controlled fluid couplings, realizing a capacity increase from 2,100 tons per hour (2,300 stph) to 2,550 tons per hour (2,800 stph), with improved reliability. This paper will present a case study of The Pittsburgh & Midway Coal Mining Co.'s North River Mine underground conveyor haulage system. These conveyors included the main line conveyors as well as a tension controlled tripper booster panel conveyor. Characteristics and performance of the coupling and control system will be illustrated, demonstrating the systems controllability, simplicity, and dependability.

Jan 1, 2002

By S. M. Khandrika

Most of the coal presently used by the utility industry is cleaned at preparation plants employing wet processes. While water is the mainstay of coal washing, it is one of the least desirable components in the final product causing a reduction of the heating value as well as handling difficulties. Currently available dewatering techniques are inefficient for dewatering very fine coal (minus 325 mesh). The US coal industry has expressed serious concern about utilizing advanced cleaning processes such as column flotation because an efficient and economical dewatering process is not available.

Jan 1, 1992

By R. E. Gertsch

Mechanical mining holds great promise for the mining industry. Realizing this promise depends on giving mine operators the capability to evaluate the higher production, the lower costs, and safety enhancement that comes with mechanical mining. The opportunities for low cost and high production must outset the high capital costs associated with mechanical excavation. Giving the mining industry the tools to effectively evaluate and successfully implement mechanical methods defines the challenges and directions of the mechanical mining industry.

Jan 1, 1994

By S. J. Bluhm

INTRODUCTION Lesotho is a mountainous area of southern Africa from which water is to be exported in an extensive tunnel system, to industrial regions inland. The related tunnelling project has involved a num- ber of drives using tunnel boring machines [TBMs] to excavate about 100 km of 5 m diameter water tunnels [von Glehn and Bluhm, 1995). This paper describes the ventilation and cooling of some of the tunnel drives from both the operational and design points-of-view with a particular focus on heat generation. There were many common features in all of the drives but this paper is focused mainly on the Hlotse drive which was 18,4 km long. The drives were ventilated using forced ventilation systems to provide appropriate air flow throughout the tunnels and face zones. In addition, the Hlotse drive required refrigeration equip- ment which provided chilled water to the tunnel. While the sec- ondary ventilation systems play an important role in gas and dust handling, the paper concentrates on the primary ventilation and cooling issues. The ventilation of these tunnels was an exacting exercise be- cause: • Rock temperatures and geothermal heat flow were high. • TBMs with relatively high power ratings were used. • Diesel locomotives were used. • Drives were relatively long. • High altitude meant a low air density. An important feature was the simulation and monitoring of the ventilation and heat flow components and the project was characterised by analysis, monitoring and ongoing tactical decision-making throughout the progress. The thermodynamics of the systems were complex because there were many interactive effects and analyses were carried out using special computer pro- grams. The monitoring confirmed the accuracy of the models, and in this manner it was possible to confidently ensure healthy and safe working conditions and still minimise costs. Local ambient climate conditions range from temperatures higher than 35 "C in summer to below -10 OC in winter. Based on available statistical data and the thermal storage/damping effects in the system, design summer ambient conditions were taken as 15 OC/25 "C wet-bulb/dry-bulb. The barometric pressure was 80 kPa and due to the altitude, the ambient air density was only 0,9 kg/m3. The local Authority specified a maximum in-tunnel wet- bulb temperature [at any point] of 32,O OC and a mean wet-bulb temperature [from all locations] of 27,5 OC maximum. The maxi- mum height of ground cover above the tunnel was 1 200 m and the maximum virgin rock temperature was 41 OC; see Figure 1. Diesel dilution criteria specified by the local Authority was a minimum of 0.1 m3/s per rated kW of diesel engine. Other requirements related to gases such as CO, CO2, NOx and CH4 [and the need for intrinsically safe equipment] but these are not of direct relevance to this paper. The actual average face advance was about 30 m/d with good days achieving 60 m/d and good months achieving 1 000 m [23 working days]. The original design tunnelling rate was 50 m/d. DESCRIPTION OF HLOTSE DRIVE VENTILATION AND COOLING SYSTEM The ventilation requirements in the tunnels were dictated by heat and diesel dilution needs. The best ventilation and cooling policy is generally a balance between using increased quantities of fresh air or refrigeration [or both]. In this particular scenario it turned out that, since the diesel emission criteria required large quantities of air, the refrigeration needs were modest. The drive was ventilated using a ducted, forced ventilation system from fans located at the portal. The maximum ventilation requirement was 51 m3/s when the drive was at 18.4 km. From a heat flow point of view, the worst scenario was a heat load of 3.5 MW when the drive was at 7 km. This was cooled by the ventilation air and a supply of chilled water to the tunnel. Refrigeration and chilled water system In the design phase, a detailed comparison was carried out between two general alternatives for providing refrigeration. First, was a system in which refrigeration sets and air coolers are installed on the TBM train; the refrigeration sets are cooled by condenser water piped to and from cooling towers at the portal. Second, was a system in which refrigeration water chillers are in- stalled at the portal and chilled water is piped into the tunnel. The detailed comparison indicated that the capital and running costs of the second system were at least 60 % lower than the in-tunnel plant. There were also many obvious practical benefits for favouring the portal system. The refrigeration plant supplied 23 11s of cold water at a temperature of 10 OC. After providing the cooling effect in the drive, the water returned to the portal where it was initially cooled in open-circuit evaporative pre-cooling towers, chilled in the refrigeration plant and then returned to the tunnel. The cold water flowed into the tunnel in an insulated supply pipe and returned in an uninsulated pipe; the water was simply circulated to the end of the pipe and returned. The cooling effect in the tunnel was achieved entirely through heat transfer from the pipe [long linear heat exchanger] and no air coils or other heat exchangers were required. The cooling requirements were satisfied by the heat transfer to the returns chilled water steel pipe [200 mm]. The pipes were eventually installed to a maximum distance of 10,8 km in what was considered a very practical and cost effective solution.

Jan 1, 1997

By G. L. Mowrey

A new coal interface detection (CID) method is under investigation by the U.S. Bureau of Mines. This novel concept is based on utilizing a passive infrared system (FIR) to measure temperature changes associated with the cutting of coal and adjacent strata. For this method to work successfully, a definite mechanical/hardness contrast must exist between coal and rock. Advantages include that FIR responds instantaneously at the coal-rock interface and it is minimally affected by dust and/or water sprays. Based on preliminary tests, results indicate that the PIR method can be applied successfully in mines having a hard immediate roof.

Jan 1, 1990

By Z. Yu

Dewatering of a -0.5 mm fine coal has been studied extensively. Deep cleaning requires however fine grinding, and dewatering of such ultrafine products presents a great challenge. Several coal samples finely ground and characterized by different wettabilities have b.een used in the filtration tests. Vacuum and press filters have been employed. In this paper only the results obtained with different flocculants (totally hydrophobic. semi-hydrophobic and hydrophilic polymers) are included. The results reveal the effect of coal surface properties and flocculant type on filtration of ultrafine coal.

Jan 1, 1994

By Robert C. Freas

The Northeastern United States is the most highly urbanized region in North America. It is also an area with a tremendous appetite for stone products. Within this context limestone has truely become an "urban ore". Its uses extend from traditional aggregate markets to lawn and garden, archetectual, chemical, agricultural, industrial, and environmental applications. This paper looks at both the occurance and uses of limestone in the northeast, and briefly examines changing patterns in consumptive use.

Jan 1, 1985

By William N. Poundstone

Since World War II, when off-track mining became popular, mining machinery has undergone much change. However, the change has been basically to make the machines more powerful, more productive and more reliable. Little change has been made, in this period, in the basic mining system. While steady improvement was made in productivity until the passage of the new Federal Coal Mine Health & Safety Act, I believe that the cost Co benefit ratio of further improvement from this basic approach of improving the existing extractive tool is not as promising as I believe may be obtained from a new approach. Consequently, six years ago Conoco and Consol undertook a comprehensive long-range R&D program to see if improvements of a more basic nature could be made in underground mining. We concluded early in our program that while many things currently limit the rate of production such as the rate at which roof can be supported, time needed to advance ventilation systems, time required to clean up and rock dust, time required to maintain and service equipment as well as time lost due to haulage deficiencies, that the key to improvement was a truly flexible continuous high capacity haulage. With face equipment in use today, mining rates can be increased with such a haulage system where the ability to support the roof exceeds the ability of conventional haulage equipment to remove the coal. More importantly, if we could develop such a system, it would set the stage for development of far more sophisticated methods of mining at the face than exist today, and as new and more dependable mining machines and methods are developed, continuous transportation will enable the gains envisaged in production to be realized.

Jan 1, 1974

By S. Tan

A computer-oriented systems simulator (CMHS) has been developed for analysis of continuous materials handling systems. Special emphasis has been placed in the model on several features which are unique to these systems. These features include periodic pattern of material arrival from several sources, several types of material to be transferred, material dispatch processes, intermediate storage capacities, and multiple material destinations. Both the deterministic factors of the continuous material handling system such as the physical decomposition of the system and the scheme and schedule of its operation and the stochastic factors such as variations of material arrival, material pattern on the conveyor, and avail-abilities of the system elements are considered in the simulator.

Jan 1, 1988

By B. G. Stone

"INTRODUCTION “Sampling is the process of taking a small portion of an article such that the consistency of the portion shall be representative of the whole” (Baxter and Parks, 1939) “An orebody is a mixture of minerals in proportions that vary in different parts of the mass. As a consequence the proportion of contained metals also varies from place to place. Therefore, a single sample taken in any particular place would not contain the same proportion of metals as does the orebody as a whole except by a highly improbable coincidence. The probable error, which would be very large if only one sample were taken, decreases with the number of samples, but it never disappears completely unless the samples are so numerous and so large that their aggregate is equal to the orebody itself, in which case the orebody would be completely used up in the process of sampling. Since carrying sampling to such an extreme would defeat its own purpose, some probable error is always present in actual cases and the practical objective is to reduce this probable error to allowable limits. This means balancing the number of samples against the desired accuracy; if there are not enough samples the result is unreliable; if there are too many, the time and expense of taking them is excessive.” (McKinstry, et al., 1948). In an actual orebody, the accuracy of sampling depends not alone on the number of samples but also on proper distribution of them throughout the orebody, for it would obviously be incorrect to take all of the samples either in a rich part or a lean part. Therefore it is important to select the places in such a way that all parts of the orebody will be represented. “For those who cultivate land which is alike arid, heavy , and barren, and in which they sow seeds, do not make so great a harvest as those who cultivate a fertile and mellow soil and sow their grain in that. And since by far the greater number of miners are unskilled rather than skilled in the art, it follows that mining is a profitable occupation to very few men, and a source of loss to many more.” (Georgius Agricola page 5 Book 1 as translated by H.C. Hoover and Lou Henry Hoover, 1950)“It is evident that mining is very profitable to those who give it care and attention”"

Jan 1, 2015

By X. Nie

A new one-step process was developed to completely eliminate iron and directly obtain pure Ni, Co, and Cu chloride catholyte from nickel rich matte by low temperature (400 0c) chlorination roasting of Ni, Co, and Cu with HCl and leaching with water (PH 7). The effects of roasting temperature, time, oxygen potential and HCI addition and leaching temperature, pH, H2S04 addition and residue sulphur on the recovery of metals and purity of leaching solution were investigated. More than 99 % of Ni and Co and 95 % of Cu in the matte was directly extracted into the solution while 99.995 % of Fe remained in the residue. The iron concentration in the leaching solution was less than 3.6 X 10-5 mol/L.

Jan 1, 1994

By S. Tuylu, D. Adiguzel, A. Bascetin, O. Ozdemir, U. Cinar

"In recent years, use of mineral processing tailings as a paste backfill has been significantly increased due to the environmental problems occurred during the disposal of the tailings in mine area. The paste material used to fill the stopes excavated is generally consisted of tailings (solid ratio: 70–85%) and cement (3-7%w/w). Meanwhile, the strength of the paste material is completely related to ratios of these materials. Cemented Paste Backfill (CPB) system is used as support depending on the roof pressure and also as an underground disposal method. Therefore, temporary strength value of the paste material gains a great importance. For example, the paste backfill material must compensate the minimum 4 MPa strength value in order to procure the permanent fortification, and the mixture cost must be minimal as well. For this reason, in this study, the Pb-Zn tailings were used to prepare for the paste backfill material using cement in order to perform the uniaxial compressive strength (UCS) tests. Additionally, a statistical experimental design and linear programming techniques was used to find the optimum mixture in terms of strength and cost. The pulp solid ratios (PSR) of the tailings and cement (by the solid) were varied as 75-85% and 3-8%, respectively. The results of this study; the optimum mixture is ~79.5%PSR and 6.8% cement ratio (by the solid) for 4 MPa UCS (28 day) and 16-17 cm slump value determined by this method with statistically reviewed experimental data. INTRODUCTION Fine-grained tailing waste materials resulting from mining activities are an important environmental problem. In terms of environmental protection, the use of tailings with paste backfill is a very attractive approach and a desirable solution to tailings management. Paste backfill, which is used to fill underground openings, is made by primarly mine tailings mixed with hydraulic binders and water. Its main benefits are not only disposal of mine tailings in underground, but also providing a certain strength to ensure a safe working environment. Therefore, it is necessary to use hydraulic binders due to durability of the system (Benzaazoua et al., 2004). Paste backfill, formed from the mix of dewatered plant tailings (75-85 wt. % solids), water and binder (3-8 wt. %) (Brackebusch, 1994; Landriault et al., 2005).Water is used to determine the chemical reactions between tailing and binder materials for strength as well as increasing pumpability. Portland cement and ash can be used as binder materials (Douglas and Malhotra, 1987). The factors which affect strength and stability of paste backfill separate into two groups called interior and exterior factors. Interior and exterior factors determine the strength, stability and deformation features of backfill in short and long terms and also affect the transportation of backfill to underground (Benzaazoua et al., 2004; Erçikdi et al., 2006; Yilmaz et al., 2010; Nasir and Fall, 2010). Material properties of tailings as well as site operations to fill the underground openings are the most important steps for the design purposes. Grain size distribution, chemical, and physical properties of tailings, and mechanical properties of paste fill material are used to understand the suitability of tailings as paste fill material (Ozturk et al., 2014). In addition, Fig. 1. is also proposed to apply a typical design for the operational stages of paste fill applications on the site."

Jan 1, 2016

By P. Somasundaran

Previous studies on semi-soluble minerals such as calcite (1) and apatite(2) and sparingly soluble minerals such as quartz (3,4) have given evidence for significant changes in their electrokinetic properties as a function of aging time. Such changes are relevant to mineral processing operations where the crushed ore particles might not have yet reached equili¬brium with the water that it is in contact with. In order that these changes be studied under controlled experimental conditions for long periods unattended or with fairly less intermittant attention, a streaming potential apparatus with an automatic streaming system was constructed. Also, a new streaming potential cell was incorporated into the system so that the effect of temperature, a variable coming into increasing usage in mineral processing operations(5), could also be studied. Conventional streaming cells(6) cannot be safely employed to conduct studies as a function of temperature since they have many glass joints that are prone to leakage, parti¬cularly under pressure, in the course of an experiment. This paper describes the new apparatus and some typical results that have been obtained with it far temperature effects.

Jan 1, 1973

By Robert A. Bauer

Investigations of bedrock within subsided areas over abandoned coal mines reveal) very little disturbance of the bedrock. In areas that have surface subsidence of .3 to 1 m (1.0 to 3.25 ft), examination of cores from exploration drilling and investigations of the boreholes by means of closed circuit television have shown that fractures are spaced at least .9 to 3.6 m (3 to 12 ft) apart and are located within a zone 6 to 15 m (20 to 50 ft) above the collapsed area in coal mines 42.6 to 112.7 m (140 to 370 ft) deep. The dip of the fractures ranges from 25 to 60 degrees, cutting across nearly horizontal sedimentary bedding planes. Typical core recovery is 80 to 95 percent within the subsided areas and 100 percent outside the subsided areas.

Jan 1, 1984