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By H. Herbert Hughes

ECONOMISTS have predicted that the present business depression ultimately may pay big dividends to industry through the cumulative savings resulting from technical improvements and merchandising advances that might never have been developed under normal conditions. Waste prevention is a sound medicine for economic ills. In theory, this prescription may be applied not' only to raw materials, but also to labor, fuel, over- head, and other phases of production. Actually, how- ever, regardless of the efficiency of operating practices, waste is inevitable in the production of many commodities. The problem then becomes one of profitable utilization of waste rather than prevention.

Jan 1, 1932

By R. T. Jones

Base metals and platinum group metals can be collected in metallic alloy form, via a wide variety of smelting processes. The recovery, or degree of collection, of the valuable metals is a function of the extent of reduction in the furnace, which, in turn, is indicated by the fraction of iron present in the feed materials that report to the alloy. An equation has been developed that relates the recovery of various metals (such as Ni, Co, Cr, and PGMs) to the recovery of Fe. This recovery equation (for each metal) is characterized by a single parameter (K?) that can either be empirically fitted to the data, or expressed in terms of the equilibrium constant and the ratios of the activity coefficients involved. Data from a number of varied DC arc furnace campaigns are presented to illustrate this behaviour.

Jan 1, 2009

By K. L. Murphy, G. Multamaki, P. M. Huck

"A preliminary evaluation, based on existing data, has been made of the implications of placing radium-barium sludge in tailings areas. The study was restricted to a consideration of possible increases in the quantities of radionuclides escaping to the environment through either groundwater or surf ace water, considering the types of tailings treated and the effluent treatment systems currently operating in Canada.IntroductionIn the recovery of uranium from ore deposits, the tailings produced by mine/mill complexes are conveyed to impoundment areas in slurry form. After settling, the supernatant is discharged to the environment together with runoff from precipitation on the tailings bas in. Currently, all operating uranium mines in Canada employ barium chloride treatment to control the release of dissolved radium to the aquatic environment. The dissolved radium in the tailings decant is precipitated with barium chloride, forming (Ra,Ba)SO4, and allowed to settle in ponds or lakes. In some instances, settling tanks have replaced ponds and flocculants have been added to aid settling. Because the Atomic Energy Control Board does not consider the precipitation ponds to be suitable for final disposal of these sludges, acceptable sites must be found. Options which have been suggested for sludge management include underground placement either in worked-out mine areas or in special chambers, or placement in the tailings areas. Conceptually, the latter alternative is attractive and probably would minimize sludge handling. This alternative would be subject to the AECB policy which requires that upon abandonment, radioactive releases from a tailings area must be within present regulatory limits and that treatment to meet these limits should not be required in perpetuity.No quantitative data exist concerning either the effect of physical and chemical conditions in the tailings on resolubilization of radium from precipitated sludges or the fraction of this additional radium which would be released."

Jan 1, 1982

By D. Harrington

The code of hoisting signals for use in mines hoisting from one level, as suggested in this publication, is submitted to induce consideration of this subject by representative groups of the coal-mining industry, such as the lithe Inspectors Institute of America, National Coal Association, American Mining Congress, and others, as well as to -furnish a code of signals for use in those mines operated in States that do not have regulatory hoisting codes in their mining laws, or regulations. The signal codes described in this publication apply only to mines hoisting from one level and to slope mines. Mines that hoist from more than one level are referred to Bureau of Mines Information Circular 7289 Suggested Hoisting-Signal Code For Metal Mine Shafts, which suggests signals for hoisting from various levels or stations.

Jan 1, 1944

By R. Matusewicz

The key drivers for the copper smelting industry are a complex mix of economic and "human" factors which combine to drive technology in new directions and can provide a strong indication of future industry trends. Recent examples have been the drive to achieve increased scale of production and resultant cost efficiencies by using a single furnace high intensity smelting vessel, and the broad acceptance of Top Submerged Lancing (TSL) technology for this duty. The development and adoption of continuous converting processes to counter the increased pressures faced by the Peirce Smith converting process is another example of the need for innovation. This paper discusses the merits of the continuous converting process, describes how the Ausmelt TSL batch converting process has been adapted to the new Ausmelt Continuous Copper Converting (C3) process in response to these industry trends and examines the Ausmelt continuous converting flowsheet options available to the end user.

Jan 1, 2007

By M. J. Little

Potgietersrust Platinums Ltd (PPRust) is Anglo Platinum?s only open pit operation. The major slope stability concern at PPRust is rapid, small-scale brittle failure on the west wall of Sandsloot open pit. In order to improve safety and mine more economically, a comprehensive slope monitoring strategy has been implemented. In the last 3 years four new state-of-the-art monitoring systems have been installed namely an ISSI microseismic monitoring system, a GeoMoS automated prism monitoring system, prismless Riegl laser scanners and a GroundProbe slope stability radar (SSR). Groundwater monitoring and visual monitoring have also been improved over the same time period. To complement the visual inspections, SiroVision digital photogrammetry is now used for predicting where future failures may occur. All these monitoring tools provide primary monitoring which is used to identify high risk areas. The SSR is then set up in that area to provide early warning of failure so evacuation can be successfully done. Fault tree analysis has proved that with this comprehensive slope monitoring strategy the geotechnical risk at PPRust is greatly reduced, allowing mining to continue safely and economically in challenging conditions.

Jan 1, 2006

The strippable reserves of bituminous coal and lignite in the United States were calculated in accordance with the prevailing conditions of seam thickness and depth of overburden in each of the several coal-producing areas of the Nation. Within defined limits of seam thickness and depth of overburden, it is estimated that there was a remaining strippable resource of 118 billion tons of raw bituminous coal and lignite as of January 1, 1968. Because of topography, natural and manmade features, and other limitations, only 45 billion tons of the resource are strippable reserves. Of this, 32 billion tons is considered low-sulfur (less than 1 percent), 4 billion tons is medium-sulfur (1 to 2 percent), and 9 billion tons is high-sulfur (over 2 percent) coal. Owing to a cleaning loss affecting that portion of strip coal that is mechanically cleaned, the 45 billion tons of strippable reserves are reduced to 39.6 billion tons of marketable coal. A brief discussion is given for each coal-producing State, summarizing past and present production, historical background, and outlook. Appendix A contains reserve data by State, county, seam, and sulfur content. Appendix B contains the general information and requirements necessary to comply with the current strip mining laws covering 20 States.

Jan 1, 1971

By J. J. Swanepoel

Titanium nitride in upgraded nitrided ilmenite (bulk of iron removed) can selectively be chlorinated to produce titanium tetrachloride. Except for iron, most other components present during this low temperature (ca. 200°C) chlorination reaction will not react with chlorine. It is therefore necessary to remove as much iron as possible from the nitrided ilmenite. Hydrochloric acid leaching is a possible process route to remove metallic iron from nitrided ilmenite without excessive dissolution of species like titanium nitride and calcium oxide. Calcium oxide dissolution results in unrecoverable acid consumption. The leachability of nitrided ilmenite in hydrochloric acid was evaluated by determining the dissolution of species like aluminium, calcium, titanium and magnesium in a batch leach reactor for 60 minutes at 90°C under reflux conditions. The hydrochloric acid concentration (11%, 18% and 25%), initial acid-to-iron mole ratio (2:1, 2.5:1 and 3.3:1), and solid-to-liquid mass ratio (1:8.33 to 1:2.13) were varied. The results indicate that a hydrochloric acid concentration of 25 wt% supplied in a 2:1 acid-to-iron mole ratio would produce the most favourable upgraded nitrided ilmenite product. The dissolution of iron in this solution reached 97 per cent after only 60 minutes. The total dissolution of calcium and titanium species was 0.01 and 0.11 wt% respectively. Hydrochloric acid can therefore be used as lixiviant to remove metallic iron from nitrided ilmenite. Keywords Titanium nitride, upgraded nitrided ilmenite, hydrochloric acid leaching, metallic iron dissolution.

Jan 1, 2011

By Lutz Markworth, Fernando Parra, Wolfram Jaspers

"The worldwide demand of iron ore and the depletion of the high-purity deposits make it necessary to recover ores in increasingly fine size fractions or low Fe content in the feed material. Impurities for Iron ore processing plants are mainly Silica, Al2O3 and Sulfides.There is a copper processing plant in Chile, which has a high content of Fe in its tailings. These tailings will be re-processed to recover the Fe and to produce a pellet feed concentrate. This challenging flotation process was developed by the customer in his own laboratory. Different flotation technologies were tested. The best results were achieved with the PNEUFLOT® (PNEUmatic FLOTation). For a feed capacity of approximately 600 t/h, a flow sheet of two flotation lines with a reverse two-stage Amine-Silica flotation followed by a single stage reverse Xanthate Pyrite flotation was developed.Because of the two impurities the process control is very critical. Not even the reagent dosing has to be flexible for changes in the feed material; also the flotation cell has to be adaptable. Continuous development of the PNEUFLOT® cell with their specific advantages and the elimination of dysfunctions in the PNEUFLOT® cell have led to a growing demand of this type of equipment worldwide for the iron ore industry within the past years.INTRODUCTIONThe worldwide increasing demand of iron ore is mainly caused by China. This has a major impact on all economics worldwide as the metal price indicates. However, not even the iron ore and steel price, but all other commodities prices and the precious metals prices are increasing by a high percentage. Figure 1 shows the iron ore (pellets) price increase for Fe and the import of iron ore by China. Figure 2 shows the imports of iron ore to China."

Jan 1, 2008

By P. Altounyan

Techniques used to safely control the roof in UK coal mines for some 10 years have been applied to a South African coal mine. This new approach known in the UK as advanced rockbolting technology, is based on applying four fundamental principles: ?Understanding the roof failure mechanisms ?Using an effective roof support system ?Designing this support using measurement ?Monitoring the performance of the system. The paper summarizes the approach in detail and describes how it is being applied by Anglo Coal, giving results obtained to date. Investigations at a number of South African coal mines, including stress measurements at two Anglo Coal mines, have confirmed that the mode of roof failure (lateral shearing due to horizontal stress) is the same as in other coalfields worldwide, and aspects of current world best practice, including the use of advanced technology rockbolting, are therefore relevant in South Africa. The stress measurements indicated a high level of stress field anisotropy and further investigation of stress conditions in South African coal mines is recommended. The most effective bolting system to resist shear failure is one with high bond strength and stiffness. Short encapsulation pull testing of existing South African systems confirmed that they have low bond strength and stiffness. An improved rockbolt system with the required performance, and features allowing rapid installation and installation quality and performance audit, has been developed and is currently under full-scale trial. Design by measurement and routine monitoring procedures including the use of a rotary telltale device are also under trial. It is anticipated that South African coal mines will be able to obtain significant safety and productivity benefits from the application of this technology.

Jan 1, 2001

By Takashi Furuyama, Sukeyuki Mori, Abel Bissombolo

"In flotation practice, a good recovery of minerals largely depends on the degree to which the valuable minerals have been liberated from the associated gangue during the grinding process. Therefore, a regular measurement of the degree of liberation can provide data for the assessment of the quality of separation and predicts the effect of changes in the grinding-classifying circuit on flotation process. Generally, the standard procedure for measuring the degree of liberation requires the preparation of polished sections - a time consuming operation that also has the disadvantage of providing an overestimated number of free particles because of the stereological nature of produced samples.The present work is an alternative approach to avoid these miscalculations and establish a system of control for fluorite flotation plants. The system deals no only with the state of liberation but also the dynamic behavior of individuals particles and mineral components within the grinding-classifying and flotation circuits. It involves methods such as sieving, x-ray diffraction analysis, study of polished sections and microscopic counting of preliminarily sieved minerals particles from a fluorite processing plant, randomly dispersed on a glass slide, but not embedded in a resin mounting medium. If a complete information on the textural properties of minerals in the ore (including its mineral components distribution) can be obtained through x-ray diffraction analysis and study of polished sections, the microscopic counting is used to determinate with enough accuracy the mineral liberation, estimate the grade of fluorite ore and products, determinate the deportment and approximate recovery of individuals particles and mineral components within the investigated circuit. For a count of 100-1000 particles in each n-size range, the counting method was found to be a particularly reliable and less time consuming operation that could substitute the chemical analysis of fluorite ore for an estimate of the grade:"

Jan 1, 2003

By V. Grujic, M. Grujic, D. Salatic

"Two areas are involved in the research work of the comminution process (crushing and grinding). The first one involves the changes of the size class distribution values that are definded by the differential equations in the function of the ore property and working conditions. The second area involves the comminution of the different levels in order to optimize the working parameters and to decrease the operational costs in the grinding process.We have studied, in detail, the possibility of functioning the crusher at the maximal loading, over 4500 kN, ball mills with diameters larger than 5.0 m and semiautogenous mills with diameters larger than 10.0 m.Using the computers, we have achieved the maximal loading range of the crusher, over Fc ? 4500 kN in the crushing process. In the grinding process, using the adequate differential equations in the automation process, we have established the correlation between the pulp mass capacity in the mill, pulp dencity, ore fineness in the pulp and recirculating ore charge.With the appopriate text, equations and graphs, this paper shows the results of our several years research work in the laboratory and in the ore comminution plant of Majdanpek Copper Mine."

Jan 1, 2003

By Gabrielle Gaustad

For aluminum, substitution of primary with secondary resources decreases energy consumption; this energy advantage creates a strong economic incentive to recycle. Several authors have raised concerns that the current sinks for secondary materials may soon be saturated, impeding subsequent expansion of recycling. This work combines dynamic material flow analysis with optimal batch planning models to quantify the significance and drivers of these pending limits under several scenarios, and thereby explore potential opportunities to increase recycling. An aluminum recycling system case was developed that includes containers and packaging, automotive, and construction products and scraps. The impacts on aggregate scrap utilization and materials cost are explored in the context of changing alloy demand and lifetime. Insights drawn from this specific case study could be applied to multi-stakeholder, systemic models.

Jan 1, 2010

By Jacques Astier

El presente texto analiza las funciones del alto horno eléctrico, el horno eléctrico de solera y el horno eléctrico de cuba baja en la industria metalúrgica, así como sus variantes en la historia actual de la siderurgia en América Latina.

Mar 1, 1964

By Greg Smith

This paper documents the use of bench testing equipment developed to enhance the understanding of, and improve upon, common roof bolt support systems. Most roof bolt systems consist of components that are covered within the scope of ASTM (American Society for Testing and Materials) standards. However, ASTM does not specify testing methods or performance standards for complete roof bolt ?systems?. It only designates testing methods and minimum performance standards for roof bolt ?components?. Improved understanding and continuous improvement of these systems is essential given the enormous impact that they have on the safety and profitability of underground mining operations. Bench testing equipment has been developed that effectively measures and records multiple points of deformation in a rock bolt support system while load is being applied. With this testing capability, an improved understanding of component and system stress distribution can be obtained and devices and methods for visual load indication can be developed. This paper is formatted as case studies where testing was performed to demonstrate load versus deformation profiles and to develop system improvement products.

Jan 1, 2012

By W. B. Timm

Introduction In preparing this paper on Recent Developments in Gold Milling Practice, the idea occurred to me that possibly the best way to deal with the subject would be to take you in thought on a visit to the principal gold mining camps of the Dominion, starting at the east and finishing up in the west, and noting, as we go, the outstanding improvements that have been made in the last few years in the practice of gold milling. Before beginning this tour, I desire to emphasize the debt this country, and particularly our mining industry, owes to that body of trained and experienced men, little heard of, but who, working quietly on their problems, are responsible for these improvements. The metallurgists, to whom I refer, have solved many difficult problems for the mining industry, in connection with the treatment of our complex ores; for instance, the silver-cobalt ores of the Cobalt district, the gold ores of the Porcupine district, the gold-telluride ores of the Kirkland Lake? district, the copper-gold ores of Noranda, the arsenical-gold ores of the Beattie mine, the copper-zinc ores of Flin Flon, and the lead-zinc ores of Kimberley. In doing so, they have maintained the high technical standards of the profession, and the practices thus evolved are noteworthy for their high degree of efficiency. When the price of gold increased from $20.67 to $35.00 an ounce, what had formerly been thought to be a low tailing became almost an ore, so that the metallurgists are now busily engaged upon the problem of putting this railing back in its proper place of being a tailing once more, or from its value, at the present price, of anywhere from 50 cents to a dollar or so per ton, to a few cents per ton. Owing to the changing prices of the metals in the world's markets, still greater improvements in metallurgical practices are imperative. An important contributory factor towards improvement in ore dressing is the aid furnished by the microscope in the examination of ores and mill products. By making possible the determination of the mineral constituents of the ore, their association, and grain size, it gives the investigator a knowledge of his problem, before he does any actual test work. In the Mines Branch laboratories at Ottawa, its use has enabled us to predict how an ore should respond to various methods of treatment.

Jan 1, 1935

By Leonard Obert

This report presents evidence indicating that when rock is stress-relieved during the course of mining or in drilling a core, it may be altered or damaged to the extent that the physical properties of the relieved specimen are not the same as those of the in situ rock. Furthermore, this type of damage may result from stress change other than that accompanying stress relief, such as the application of a relatively large compressive stress. In some instances the damage is microscopic, manifesting itself as incipient cracks or the failure of individual crystal bonds. However, if the sample is taken from a high-stress area, macroscopic damage may occur.

Jan 1, 1962

By J. T. Nel

The establishment of a pilot plant for the continuous production of titania pigment and nano-titania is discussed. The plant was designed, constructed and operated on the Necsa site. The TiO2 production capacity is 7?10 kg.h-1 by the reaction of TiCl4 and O2at>1000°C. Liquid TiCl4 is sprayed under pressure into a plasma reactor where it evaporates and reacts with O2 to form TiO2. Process optimization has allowed for continuous production without any clogging or blockages. The primary advantage of the plasma-assisted process is the possibility to recover and recycle the chlorine values in high yield as Cl2 for use in the manufacture of TiCl4. The HCl formed in most conventional fossil-fuelled processes makes Cl2 recovery and recycling much more difficult. Particle size distribution analysis of the fine, white product revealed a d50= 125 nm. The raw product consisted of 60% rutile that could be increased to 80?100% rutile by post-annealing. The specific surface area (SSA) of the pigment was 8?20 m2?g-1(BET). According to the CIE colour index the ?whiteness? (L*>95) of the plasma-produced pigment was better than that of several commercially available pigments. The particle size could be manipulated by controlling the TiCl4 feed rate, gas flowrates, and the particle quench rate and residence time. Nano-sized TiO2 powders with a particles size (d50) as small as 50 nm were also successfully produced in this way.

Jan 1, 2010

By Osvaldo A. Bascur, J. Pat Kennedy

"The profitability of mining and metallurgical operations continues to lag behind that of other industries despite the technical advances that have occurred in recent years. A primary reason for poor performing in this economic sector is the lack of integration of mining and metallurgical information. The mine cut-off grade can be optimized if mining and metallurgical engineers have the data to optimize milling for the type of ore in hand.Integration of mine transactions, stockpile inventories, process flows and assays is the key to determining the economics for each blast strategy in a mining site. Real-time information from manufacturing assets greatly affects the profitability and flexibility of a company, but gross errors from faulty sensors, inaccurate instrument calibration, or incorrect process models may corrupt actionable information. New software tools can model the process, sift through available data to identify and eliminate gross errors, and use statistical data reconciliation to create materially balanced and consistent readings. The reconciled data is unified for use by both monitoring and decision making processes.Creating a real-time information environment where upgrade and change are allowed is becoming an accepted methodology to accelerate and simplify the integration of applications such as production monitoring, equipment performance management and yield and inventory management."

Jan 1, 2003

By Hua-Zhong Yu

Gold is one of the most widely used substrate materials for self-assembly. Self-assembled monolayers (SAMs) prepared from alkanethiols and their derivatives on gold are the most reliable and well-studied systems to date, which have attracted much attention because of interest in two-dimensional molecular assemblies, and of their potential applications in molecular devices, sensors, and functionalized interfaces. Gold electrodes are also very important in microelectronics and electroanalytical chemistry. This work reports the characterization of a new type of gold substrates for self-assembly. The gold substrates are constructed from recordable compact disks (R-CDs) with simple and straightforward wet-chemical treatment, and can be made at desired sizes and shapes that satisfy different experimental needs. In particular, an easy, inexpensive, and reproducible method to prepare self-assembled monolayers (SAMs) on CD-R gold substrates after removing the protective polymer films with concentrated nitric acid was described.

Oct 1, 2003