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By John B. Wright

This paper describes laboratory techniques and subsequent results of Bureau of Mines research to produce chlorination-grade feedstock from an abundant, low-grade, domestic, rock ilmenite ore. The research is part of the Bureau-effort to devise technology that may help decrease U.S. dependence on imported raw materials. A rock ilmenite containing about 46 wt pct Ti02 was smelted in an electric arc furnace with coke, woodchips, and Na2C03 to separate most of the iron as pig iron and to form a low-iron, titanium-enriched slag. The slag was ground, pelletized, oxidized, and then sulfated with mixtures of SO2 and air in a continuous 4.5- to 9.1- kg/h apparatus at 1023 to 1223 K. The sulfated slag, containing 60 to 65 pct TiO2, was reground and leached in water at ambient temperature to decrease the combined levels of the troublesome Ca, Mg, and Mn impurities from 7.0 to 1.7 wt pct. At levels of more than 3 wt pct, these impurities contribute to operating and disposal problems, The final product was upgraded to about 84 wt pct TiO2. This material potentially is suitable for chlorination in a fluidized-bed reactor. The most favorable results were achieved with leached slag sulfated at a feedrate of 4.5 kg/h and at temperatures of 1073 to 1123 K.

Jan 1, 1984

By N. Kanari

One of the criteria to define the market value of chromite concentrate is its chromium to iron ratio. Changing this ratio for a definite chromite mineral is impossible by physical processing. This study investigated the possibility of increasing this ratio through the carbochlorination and the oxychlorination of chromite concentrates. Experiments are carried out up to 1000 °C. The characteristics of samples and reaction products are determined by SEM, XRD and chemical analysis. The carbochlorination of a chromite concentrate at about 600 °C leads to the . selective partial elimination of iron allowing a higher Cr/Fe ratio of the treated concentrate. Selective extraction of iron could also be achieved at about 950 °C by oxychlorination. In this case, a part of chromium contained in the concentrate is recovered as chromium oxychloride. The obtained residue had high content of Cr, Mg and A1 oxides. Such material has probably better chemical and thermal properties that may. be useful for foundary and refractory applications. Two flow-sheets for the beneficiation of the chromite concentrates using carho- and oxychlorination are suggested.

Jan 1, 1997

By M. Suzuki, M. Dobashi, M. Kahata, T. Yoshida

Almost 30% of steel in Japan is produced by electric arc furnace (EAF) treatment of iron scrap. EAF dust includes approximately 20 wt % of Zn and 3- 5 wt % of CI and is treated by the pyrometallurgical processes to recover Zn as Zn oxide. Direct hydrometallurgical processing is one of the most effective methods to recover high purity Zn. In this case, CI in the EAF dust is dissolved in the liquid phase by leaching, and the CI anion in electrolyte attacks anodes which are commonly made of a lead base alloy. Several processes have been proposed to remove CI anions from acidic sulfate solution. In this study, an electrolytic process was examined to eliminate CI anions from Zn sulfate electrolyte. From our study it can be said that the elimination rate of CI anion depends on the anode material ( i.e., the elimination rate is Pb-Ag alloy == Pb > DSE== Pt). In industrial Zn electrowinning process, the electrolyte contains Mn, which means the influence of Mn should be considered in the elimination of Cl. Mn dioxide deposition on an anode plate reduces the efficiency of CI removal. A periodical reverse current electrolytic system was examined to prevent this efficiency decrease, and deposited Mn dioxide could be removed very rapidly when the current is reversed. More than 95% of CI anion could be removed by this method in a shorter period than direct current method.

Jan 1, 1997

Alluvial mining even of shallow deposits is often economically a marginal proposition and causes significant disruption of the land surface through the need for large scale excavation. In-situ leaching using chlorine-based solutions eliminates the need for excavation, the disruption of surface activities, and may greatly reduce processing costs and improve recovery especially of fine gold. A spreadsheet model has been developed to design and analyse the economics of in-situ leaching of alluvial deposits. In-situ leaching of shallow deposits may be achieved in a number of ways including solution infiltration via perimeter ditches or the use of injection and production wells. In most instances deeper alluvials may only be processed using well systems. Two deposits are analysed in this paper. The first consists of one metre of payable wash beneath one metre of overburden. Some thirty fields per year are treated processing 450 000 BCM per year at a cut-off grade of around $4/tonne ($8/rn3 or the gold value equivalent of 0.26 gh or 0.52 g/m3). The principal costs are well drilling and labour. Sensitivity analysis indicates that doubling the throughput halves the cost. The economics of the project are relatively insensitive to reagent costs and consumptions, and halving the recovery doubles the cut-off grade. Shallow deposits treated using the infiltration ditch system may be marginally cheaper and more conveniently managed although this depends on the relative cost of digging the perimeter ditches. In a second example, deep leads with one metre of wash beneath 30 metres of overburden necessitate significant drilling and feature reduced throughputs as a consequence. In the example chosen 30 fields a year are processed for an annual throughput of 65 000 tonnes costed at around $20/tonne (1.4 g/t Au equivalent, $40 /m3). Sensitivity analysis indicates that throughput, and drilling cost per metre are not important but there is a high sensitivity to recovery and to the depth to payable wash.

Jan 1, 1992

The author presents various procedures for the choice of dri-ving systems for mining, including the method of indeterminate Lagrange factors and linear programming.The possible application of the points-awarding method is demonstrated.It allows for taking into account both surd and commensurable characteristics of a driving system for mining. Also, the method of economic efficiency factors is outlined.All these methods make possible the best choice of a driving system, from the as-pect of electric energy saving. Two examples are given.

Jan 1, 1985

By FRANK RIEBERS

IN DISCUSSING the selection of a geophysical method, much of what the writer will say is applicable to any of the various methods and to their use in prospecting, whether for oil or for other minerals. Specifically, the writer's subject is the problem, particularly pressing on the Pacific Coast, of checking the rising cost of the discovery of new fields by the proper employment of geophysical methods. Table I was prepared from statistics published by the California State Milling Bureau. The writer selected five of the largest a:ld most active companies operating in California, segregated the number of wild-

Jan 1, 1930

By Hans Lundberg, Basil T. Wilson, H. Steuart Scott

FOR the benefit of those readers who may not be in close touch with present practices in the geophysical prospecting for ore, brief reference will fiat be made to the advantages and shortcomings of the methods to be discussed. Magnetic and electric methods are generally accepted as the most useful for ore prospecting. By magnetic methods, magnetic intensities that are not normal may be recorded and outlined. From these can he located concentrations of such highly magnetic minerals as magnetite or pyrrhotite, which sometimes occur in such large masses that they are of economic value in themselves. More often. however, these magnetic min¬erals are associated with others, such as copper, zinc, lead, gold, and silver, which, if existing in sufficient concentration and quantity, may constitute valuable ore bodies. It is therefore only when pyrrhotite and magnetite are present in these bodies that the magnetic method can be used to indicate their presence.

Jan 1, 1945

By Pope Yeatman

In my experience, perhaps the most interesting problems came up during the testing, prospecting, developing and equipping of the Chuquicamata and Braden Copper Mines in Chile, and it is proposed in this article to give as briefly as possible what some of those problems were, their solutions, and the decisions made as to the different methods to be employed. The romance of mining is still a great lure to the young man who is making a choice of a profession to follow. The thought of travel to strange and out-of-the-way places, the glamor of pioneer life, the excitement of discovery, the constructive work of building something, entirely "from the grass roots up," or of reconstructing a played-out property and making a success of it-all of these phases have a strong appeal and often influence the young man in the choice of mining as a profession. That great engineer, Col. Seeley Wintersmith Mudd, whom we are endeavoring to honor, while having too much common sense to have been materially influenced by the romance of mining, certainly experienced all of the

Jan 1, 1932

By Jorgen Elbrond, Yve Lizotte

"A mine evaluation method based on the use of a computer program that models mining with an open-ended dynamic program is presented in this paper. It is demonstrated with an example how the method is applied, how some of the decision variables are related in the particular industrial environment and how these decision variables affect the economic benefits of mining.IntroductionTwo distinguishing characteristics make mining a particular industrial environment: exhaustible resources of a given ore deposit and heterogeneousness of the ore grade spatial distribution in the ore deposit. These characteristics, inflation, uncertainty and cyclical price variations which greatly affect estimated cash flows also contribute in rendering difficult the evaluation of the economic outcome of mining at the preliminary planning stage.Decision variables and their ranges are associated with the mine plan; basically, they include choices of the mine's nominal capacity (mining and milling), the sequencing of mining through the deposit, the ranges of possible production rates and cutoff grades, and the stockpiling policies. The mine's nominal capacity must be decided at the planning stage, but this capacity choice must take into account flexibility to modify other decision variables as mining commences and uncertainty resolves.Although it is generally accepted in discounted cash flow analysis that the sequence of mining must proceed from the richest to the lowest-grade stopes (with correspondingly ajusted cutoff grades), this may not produce optimum benefits when cyclical price variations are considered.Mining rates and cutoff grades can also be adjusted to changing economic conditions, taking into account the limited resources of the ore deposit. Thus, when prices are thought to be in the trough of a cycle, production can decrease to preserve ore for expected greater future profits. When prices rise, mining rates can increase possibly even over the mine's nominal capacity. In both cases, the machinery's effectiveness shall not be-optimally utilized; this will be reflected particularly by the variations in the concentrator's metal recovery and the concentrate grade output."

Jan 1, 1982

By Newell G. Alford

With the workable area of coal prospected and known as to workability and quantity and sampled and tested for desired quality comes the determination of the projection and method of working. The best method will be the one supplying the greatest degree of safety, the most merchantable product, the minimum average cost per ton with the largest yield of recoverable coal. Based on coal elevations, taken at the bottom of the seam on all known outcrop exposures, prospect openings or drill holes, coal contours are made on the map to be used in developing the mining plan. The contour interval should be as close as available information will permit. For general utility in layout of mining, haulage, drainage and ventilation, a map scale of 400 ft. per in. is preferable. In mountainous sections, location of the main out- crop opening or hoisting shaft is often limited by the available railroad route and amount of land level enough for a plant site. In level country, where a tipple and hoisting shaft may be placed at will, choice of the plant site should depend on the minimum average underground haul for the total coal to be worked to the new

Jan 1, 1932

By Sami Hindstrom, Travis Orser, John Starkey

"A great deal of effort has been expended in the last 11 years by the authors and others to identify the correct power required to grind ore in a SAG mill, by developing ore hardness variability functions for the ore body to be mined. This paper describes the next step in the SAG design process, which is choosing a SAG mill to accomplish the required specified design performance.At the test work stage, each ore hardness data point is a unique and discreet bit of information that represents the energy required to grind the ore represented by that sample at optimum SAG conditions. When the design criteria are set, it is now considered necessary that the required power draw in the mill chosen be provided at optimum conditions as well.Based on actual 3-ft diameter pilot plant results, we can now show that the grinding efficiency and throughput drop when the optimum load limit is exceeded. Future work is expected to show a similar reduction in efficiency when exceeding optimum speed. Providing specified power by exceeding these optimum conditions is not adequate and leads to a lower cost but underperforming SAG mill.It is possible in some cases to modify a SAG circuit to force it to perform better, but this often takes time, much effort and costly modifications. In most cases the capital spent on a properly sized SAG mill may prevent production losses that would be many times greater over the extended start up period. This is the direct result of choosing the proper SAG mill at the start.INTRODUCTIONThe sequential steps required for the design of any grinding circuit, have changed dramatically in the last seven years. Previously, it was considered necessary to do six foot diameter SAG mill pilot plant tests on representative samples of minus six inch ore (F80), in order to understand design requirements. It can now be shown that this method is costly and not likely to produce the desired result because it is difficult to recover six-inch material from deep within a new mine. The representative nature of the sample is often compromised when the sample is selected."

Jan 1, 2003

By M. Saghaeian, R. Hejazi, H. Abedini, M. Zare

Water recovery in mineral processing plants is one of the most important subjects because water supply is a critical matter economically and environmentally, especially in desert areas. In this paper, the filtration behaviour of two iron ore tailing sample has been investigated using laboratory scale vacuum and pressure filtration units. These samples including tailing from Sirjan and Zarand concentrate production plants with the d80 of 94 and 41 micron, respectively. The results show that by using vacuum filtration the cake moisture content of Sirjan sample would be about 24%. But the filtration time is too long and vacuum belt filter cannot be used in industrial scale. Adding about 40 g/ton of flocculant would decrease the filtration time by about 30% and make the vacuum belt filter appropriate for dewatering of this sample. For Zarand tailing sample, the vacuum filtration would produce a wet cake by about 31% moisture content. Filtration time is too long and adding flocculant would not improve the results very much. So pressure filtration must be used for dewatering of this sample. The results of laboratory tests show that using pressure filter would reduce the cake moisture content to 21%. The filtration time is logical, so this process can be used for Zarand tailing dewatering.

Jan 1, 2014

Choosing an Effective Dust Suppressant

Sep 13, 2010

By Hans Hamrin, Bruce Kennedy

Once an ore body has been probed and outlined, and sufficient information has been collected to warrant further analysis, the important process of selecting the most appropriate method or methods for mining can begin. At this stage, the selection is preliminary only, serving as the basis for a project layout and feasibility study. Later, it may be found necessary to revise the details, but the basic principles for the ore extraction should remain a part of the final layout. With respect to the basic principles employed, relatively few mining methods are used today. For the purposes of this presentation, the principles are classified as follows: 1) For naturally supported stopes, the available methods are room-and-pillar mining and sublevel stoping. 2) For artificially supported stopes, the available methods are shrinkage stoping, cut-and-fill mining, square-set mining, and longwall mining. 3) For caving methods, the available techniques are sublevel caving and block caving. Due to the uniqueness of each ore deposit, the variations on each of these methods are nearly limitless. It is impossible to include even the major variations in this chapter; the goal of this chapter is to present the principles as a guide to the mining engineer in adapting the general methods to specific needs. The selection process described herein is intended to supply the techniques by which the candidate methods available for a given ore body can be reduced to one or two feasible approaches. The feasible approaches then can be evaluated in detail, and the particular modifications can be investigated. In describing costs and economic factors, all values herein are expressed in terms of 1978 US dollars.

Jan 1, 1982

Provide guidance on the selection of millisecond initiator delays between blastholes in surface mine blasting to provide a desired degree of rock fragmentation consistent with safety and vibration considerations. The Problem Blasting remains the primary means of fragmenting, rock for all kinds of mining, quarrying, construction, and excavation activities, and it is the only practical and economic method of breaking up and moving large amounts of material such as coal overburden and stone aggregate. Because of the large amount of blasting done, typically using 4 billion pounds of explosive to break about 8 billion tons of rock annually in the United States, a small improvement in blasting performance will have a significant productivity impact. Standard blasting practices involve the selection of time delays in a blast for at [cast three purposes: (1) to control energy flow to minimize adverse vibrations, (2) to provide sufficient time relief for good rock displacement, appropriate muck pile shape for digging, and the prevention of collar violence, misfires, and flyrock, and (3) to provide an appropriate amount of interhole stress wave and gas pressure action for a desired fragmentation size distribution. Timing guidelines that exist are based on subjective observations rather than measurements, even for the relatively new casting methods. Until this Bureau study, no definitive analysis had been done to quantify the fragmentation and productivity of full-scale blast rounds as functions of precision delay timing.

Jan 1, 1989

The main goal of this paper is to present readers with recommendations for choosing coaxial cables appropriate for mining applications of Time Domain Ref 1 ectometry (TDR) to monitor rock mass movements. Prior to discussing the recommendations, mining applications are illustrated with examples and the operating principle of TDR is discussed briefly. Items that affect the result of the monitoring system performance include the coaxial cable selected, the grouting material used, and the installation procedure.

Jan 1, 1986

By Lorne Roberts

"This paper describes: how Falconbridge's fire protection system meets the needs of the Lockerby Mine; why the system was chosen over other alternatives; how it is unique, but can be applied to any underground situation; details of the system; how it was installed; the role of a fire protection company; and general considerations when choosing afire-suppresant system.IntroductionIn May 1981, after about three years of searching for the best fire protection system for the re-opened Lockerby nickel mine at Whitefish, near Sudbury, Ontario, Falconbridge Nickel Mines Ltd. installed an AFFF type of fire suppression system. It was designed and supplied by the Fire Protection Systems Division of Levitt -Safety Ltd.The system protects against loss of life, equipment and/or production, and it complies with legislation should fire occur in a fuel storage area and/or scooptram garage and service bay at any or all of the three levels near Shaft No.2.About 18 months after Levitt-Safety began working with Falconbridge, the system was designed and installed at a cost considerably less than that which would be incurred if fire damage caused the loss of two days of production.The fire protection system, which overcomes a limited water supply, is a self-contained balanced pressure proportioning system. It senses the flow and automatically determines the correct concentration of foam to water. It is triggered by a release mechanism which operates a bank of nitrogen cylinders, which in turn pressurize a pressure vessel to expel the foam concentrate and water from the tanks. This solution is piped to sprinkler heads in the specific area."

Jan 1, 1982

By R Tom Watts

The blasting industry has changed more in the last five years than in any period to date. The equipment utilized to load boreholes has changed in response to more precise blasting products and programs, and the need to maintain tighter control over product formulations produced by bulk loading equipment. Tread Corporation has built over 1,300 heavy ANFO type bulk loading units currently operating in over 40 countries worldwide. These units have been designed to meet almost every possible loading scenario but there are always new situations that require special designs and configurations to meet the challenge. The focus of this presentation is to make you aware of the process that should be used to determine the equipment best suited for your application. We will discuss loading cycle times, delivery rates, multiple product mixing capability, capacities, manpower utilization, regulatory compliance, and where and when to use automation in the loading process. We will also discuss the suitability of chassis with regard to ground pressure, turning radius, terrain, weather conditions as well as highway suitability. The US Bridge Law as well as laws that cover the concept of axle loading and spacing will be covered. Through new computer aided design and modular design capabilities, you can now have almost any configuration required to meet your bulk loading objectives. We will also review the range of equipment currently available in the market place and discuss tradeoffs between price, capacity, and complexity.

Jan 1, 2000

By James J. Olson, Richard A. Dick

Blasting practices have shown a recent trend toward larger blastholes and larger burdens and spacings, although some operators, after reconsidering the situation have gone back to smaller blasthole sizes. The greater pull-down capabilities of larger drill rigs and the greater bearing strength of large diameter drill bits give penetration rates for large diameter blastholes approaching, and sometimes exceeding, penetration rates for smaller holes. In practically all cases, large diameter holes can be drilled more quickly and cheaply, based on volume of hole, than small diameter holes. The industry's shift to dry blasting agents and slurries, products which perform more dependably and efficiently in larger diameters, gives an additional advantage to larger boreholes.

Jan 3, 1972

Choosing the correct delay time for many blasting applications is an important and critical blast design parameter for controlling fragmentation, muckpile shape, swell, digability, throw, ground vibration and airblast. BAl and its affiliates have monitored thousands of full scale blasts in a variety of field conditions, spanning over 15 countries, with sophisticated blast monitoring instrumentation. In some blast environments, a small change in the choice of delay times used had a dramatic and pronounced effect on the overall blast results. In other blast environments, large changes in the choice of delays used had absolutely no effect on the final results in terms of specific outputs. In environments which were sensitive to the delay selection, the type of explosive, dynamic response time of the rock mass (TMIN), integrity of the material, burden and rock mass geometry, all played a very important ,role.

Jan 1, 1998