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What is your assessment of the status of the mining industry as we see some evidence of an economic recovery? I am optimistic about the short and midterm prospects for the industry and, hence, for the professionals in the industry that constitute the majority of the SME membership. All who will read this interview recognize that the quality of life we enjoy today is largely a result of our achievements in the mining and minerals processing sectors. I believe that the sustainability of that quality of life and the aspirations of other sectors of the global community to attain that same lifestyle will significantly depend on the continued successes of these industries. Looking at some of the traditional economic indicators, we see predictions of continued increases in gold prices during the next 12 months as a new round of quantitative easing keeps real interest rates low and drives excess capital flows from countries with trade surpluses - who have traditionally parked their money in U.S. government bonds - into other investable assets, such as gold. On the fuel side of the industry, we have during the last decade seen a steady rise in the cost of coal, and some of the recent spot prices have seen dramatic increases. Some suggest that coal prices may rise sooner than anyone expects, as global reserves are revised downward. This is based on the hypothesis that some of the main coal-producing countries are overestimating supplies and that coal prices could start rising far sooner than anyone thinks - with obvious serious implications for energy policy. Those forecasters note that, for the past couple of decades, global supply has been dropping at a faster rate than consumption.

Jan 1, 2011

By E. C. Winegartner

In producing and selling coal, the coal company is faced with many different parameters by which the quality of its product is evaluated. One type, which we choose to call the economic parameters, includes moisture, ash, sulfur, and Btu's. These are reasonably well understood by both the coal supplier and the customer, and the dollar values can be placed on them. This is the group of parameters of primary interest to most purchasing agents buying coal. A second group of parameters governs how the coal will behave in the boiler itself and is of primary concern to the engineers designing the boiler and to the men who must operate and maintain it. Since we have not yet learned to put dollar values on these parameters, they generally show up in coal contracts simply as cutoff points, the purchaser simply saying that he will not accept coal outside of certain limits.

Jan 1, 1975

By RICHARD A. THOMAS, Liming Yuan, Lihong Zhou, DAVOOD BAHRAMI

Mine ventilation simulation software has become an essential tool for the mining industry to design and manage mine ventilation operations. Building a well-calibrated mine ventilation network is time consuming, however, and requires great effort. In the last several decades, the mining industry has seen a steady increase in the use of air velocity sensors to monitor airflow and detect unexpected abnormal airflow in some key locations in underground mines. The present research work was carried out to explore the possibility and methodology of calibrating a ventilation network model using atmospheric monitoring system (AMS) data on a routine and ongoing basis.

Aug 1, 2022

By Jaime Adasme, Héctor González, Benjamín Celada

"INTRODUCTION Santiago de Chile is a 7 million inhabitant city which has a 103 Km long subway network operated since 1975 by Metro S.A. This network is used on a daily basis by 2.3 million people. In 2012 Metro S.A. started the biggest enlargement of the network in its history, through the design and construction of the new Line 3 (21.7 Km) and Line 6 (16.5 Km). The detailed engineering contract for civil underground works of Line 6 (L6) was awarded to the Consortium integrated by ZAÑARTU Ingenieros Consultores and GEOCONTROL S.A., in which Geocontrol was in charge of the design of 11 stations and 14.5 Km of tunnel. L6 crosses L3 in Ñuble and Ñuñoa Station, L2 at Franklin Station and ends, intersecting L1, at Los Leones Station as shown in Figure 1. LOS LEONES STATION DESIGN Location and Characteristics Los Leones Station is placed at the North end of the L6, next to the same named station of the L1 and it has four construction units, as is shown in Figure 2: I. Access Shaft (49 m x 47 m). II. Access Gallery (34 m long). III. Station Tunnel (120 m long). IV. Connection Gallery with L1 (104 m long). A singular feature of Los Leones is that the western section of the station tunnel, built from the access gallery, is located below an underground parking lot which is located in Providencia Avenue, as shown in Figure 3. It is important to highlight that the distance between the vault of Los Leones Station Tunnel and the foundations of the underground parking lot is only 6 m."

Jan 1, 2016

By John C. Schneider

During the past decade, operators and researchers have worked toward a better understanding of the mechanisms operating in flotation. As reported by W. J. Trahar in 1981, this work commenced with the operators determining a relationship between recovery and particle size. They defined three particle size ranges, that being fine, intermediate and coarse. It was noted that the fine and the coarse ranges had slower flotation rates than the intermediate range as demonstrated by their lower recoveries.

Jan 1, 1998

By Walter H. Schwedes

Ore grinding mills are really just slowly rotating barrels, but barrels that are growing in size so fast that the application of electric drives for them is rapidly approaching a technology like that for wind tunnels or pumped storage drives. This application is particularly worthy of care because some 40% of the 75 megawatts of power used by a large copper ore concentrator, or some 60% of the 200 megawatts supplied to a large iron ore concentrator, are for grinding. These ore plants are located where the ore is, not where a utility happens to be. So, the challenge is not only to choose a drive and .power transmission for reasonable cost, high performance, reliability and minimum maintenance, but to afford the interface between mill drive and power distribution and source systems to minimize the whole ore plant's monthly power bill, or costs of self generation. Conclusions can be reached in optimizing a drive selection only for each particular ore plant's set of parameters, but by identifying the criteria for selection and then weighting each type of drive per criteria, yardsticks for final choice become apparent. This is the purpose of this paper. Grinding action takes place inside the barrel, where the ore charge is ground with the aid of balls, or mill length rods, or large chunks of ore as in autogenous grinding.

Jan 1, 1972

By J. Stoll

In May 1998, Hanson Aggregates Midwest, as an outcome of mine planning, offered a 10-acre tract of land containing the famed fossil-bearing Silica formation, to the City of Sylvania, OH. in the form of a 99-year lease agreement. The Olander Park System, and Ohio code park operating within Sylvania Township, was then approved by Hanson and the City to manage and fund the park. All parties signed the lease in August of 1999. In November 2001, local residents voted to fund the park by a margin of 2 to 1. The park will consist of a shallow (approx. 20 ft.) former cement production quarry that is 700 ft. long by 300 ft. wide. Hanson’s motivation and vision for the park was fivefold: 1) the site was located away from long-term reserve access; 2) it would serve nicely as buffer property for the active quarry; 3) it had become an area of illegal dumping by locals in the past; 4) trespassing and safety issues would be limited by allowing supervised usage; and 5) the shallow outcropping contains the world famous, fossil-bearing Silica shale. Hanson will supply shale to the park perpetually via stripping activities in the process of uncovering quality construction aggregate limestone and dolomite reserves. Thousands of enthusiastic fossil hunters have already combed throughout the shale in their quest for “treasures”. The park’s master plan also features nature trails, picnic areas, a fossil-themed play area, amphitheater, visitor’s center and gift shop. Given the natural and people resources that Sylvania Fossil Park will have to offer, Hanson is confident that it will become the premier invertebrate fossil hunting site in the United States. It will also remain a solid community relations vehicle for years to come.

Jan 1, 2003

By R. Mensah-Biney, M. T. Hepworth, K. J. Reid

The kinetics of gold-bromide loading onto activated carbon was investigated in a batch stirred reactor. Based on a second-order equation, the amount of gold adsorbed by the carbon was correlated with time. From a 30ºC solution containing 25 ppm Au and 0.8 g/L carbon, the rate constant for gold-bromide species onto activated carbon ranged from 0.27 x 10-3 to 1.2 x 10-3 (kg/t)-1 min-1. The equilibrium saturation capacity (Qe) was 36 ±3.0 kg/t from the same system. The rate of loading increased with increasing temperature and decreasing particle size, pH and solution gold concentration. The calculated activation energy (Ea) was 8.8 kcal/mole, significantly higher than those reported for physical adsorption. The equilibrium saturation capacity (Qe) increased with increasing concentration of gold in solution but was independent of other variables such as temperature, agitation speed, particle size and pH. These rate constants and equilibrium saturation capacity for the gold-bromide species are higher than those reported for the gold-cyanide systems.

Jan 1, 1998

By F. Shigeyoshi

The development of pelletizing during the last ten years has continued, however, self-fluxing pellets have not been regularly and commercially produced for use in blast furnaces, except as Kobe Steel, Ltd., Japan. This paper tells about unique developments for self-fluxing pellets, and their effects when used in Kobe Steel's No. 3 blast furnace at the Nadahama Works (inner volume 1845 Nm3, hearth diameter 9.5 m)., Several phases of the pelletizing process are discussed individually, and also their relation to performance in blast furnace operation. Special emphasis is placed on proper preparation of the limestone added to the raw materials, and indurating at optimum conditions. Means of improving pellet quality by correct control of size distribution of the raw materials used in pelletizing, and indurating temperatures, are also discussed. As basicity (CaO/SiO2) of pellets increased 0. 1, coke consumption decreased 3. 8 to 4. 2 kg per ton of hot metal, when using 70% pellets in the iron burden.

Jan 1, 1969

By Yi Luo, FENGLIANG WU

Mine gob has long been a safety concern in the coal industry due to the air flowing through the gob area. Therefore, knowledge of the airflow distribution and locations of hazard zones in longwall gob is important to prevent and control these hazards. Due to the inaccessibility of mine gob, many numerical studies have been performed to simulate gob air leakage using computational fluid dynamics (CFD) programs, but most of the studies isolated the gob from the mine ventilation network (MVN) with only predefined pressure boundary conditions. The MVN is, in fact, not static in a dynamic longwall mining process, and it consequently changes the boundary conditions and the gob flow field (GFF). Therefore, the MVN should be incorporated in the CFD model to prescribe the transient boundaries. However, it is very challenging to couple the 1D MVN and the 2D/3D GFF to make the mine ventilation simulation realistic. This research uses a proposed novel finite tube method (FTM) to couple the MVN and GFF. In the FTM, the GFF is discretized into a finite number of flow tubes, each of which is formed by two adjacent streamlines. These tubes connect the MVN into a new coupling network. Based on the FTM, a model for gas migration in gob is established for delineating the hazard zones of explosive methane concentration and spontaneous combustion.

By Hans W. Schreiber, Rudi P. Fronk

IINTRODUCTION Widespread activities in precious metal projects in the western U.S., Australia, Canada and other parts of the world have opened a flood-gate of consul- ting expertise to aid and accelerate the development process. Utilization of outside expertise has taken on many shapes and forms that have in some instances actually "decelerated" or "retarded" project progress. Small mines are especially vulnerable to apparent false-starts and misdirections, be- cause of their generally lower capital commitments, shorter lead times and limited mineral in-house expertise. Mine development for small mines requires fundamental approaches by knowledgeable consultants that are timely and cost-efficient and in line with accelerated development, if they are to be successful. The development process is obviously that process which brings a given deposit into production. Or, put another way, the process comprises all activities, decisions and commitments which take place from the moment an authorizing entity (usually a board of directors) com- mits to development and production (usually on the basis of a final feasibility study) until the first ton of ore is processed to a saleable product. The activities, decisions and commitments over a development period--such a period can range from as short as a year or less to as long as 5 years or more--are many, highly varied, and often interdependent. The development period is also particularly risky, not only because of the varied and interdependent decisions and commitments, but also because of capital demand amounts. Delays in the development process are thus particularly costly - sometimes so costly that small and often undercapitalized mining companies, failing to reach production and a cash flow within a planned period, face, if not bankruptcy, at least severe equity dilution or particularly onerous and restrictive covenants on additional loan financing. It therefor behooves especially small mining companies to examine ways to accelerate development. By doing so, the development process may actually meet planned scheduling. The development process generally comprises environmental impact studies completion, final engineering, permit- ting, financing, equipment and machinery procurement, contractor selection and construction -- such activities largely being overlapping. The paper addresses what the small mines operator or the small mining company can do with consulting firms to accelerate development. By "small mines" is meant open pit operations of 2000 tpd or less and underground operations of 500 tpd or less. By "consulting firms" is meant entities who do not possess an engineering and construction capability, such as Derry Michener Booth & Wahl, Pincock Allen & Holt, Behre Dolbear-Riverside, etc. The paper concentrates on gold projects. PRIORITY CONSIDERATIONS Of the items listed in the previous paragraph which comprise the development process, the two which most consistently appear to cause delays are permitting and financing. The former's delays can be due to political overtones and thus the delays may not be reasonably foreseeable. The latter's delays are most often due to inadequate preparation, and thus are avoidable. For the reason stated above, and considering that financing is fundamental to all of the activities which constitute the development process, the paper focuses on financing as the priority item which can most assist in accelerating or retarding the development process.

Jan 1, 1987

By J. A. González-Anaya

This laboratory work presents a study of the effect of ultrafine grinding on the gold recovery of a highly refractory gold concentrate. The particle size of the concentrate was P80 = 46 µm and the main species present were quartz (28.58%), dolomite (25.63%), pyrite (20.93%), arsenopyrite (15.39%) and 112 g/t gold. After optimizing hydrated lime and lead nitrate additions, standard cyanidation with 1% NaCN, pH = 12.3, 25% S/L permits to recover only 9.4% of the gold. Different particle sizes were submitted to cyanidation. When the concentrate was ground to ultrafine sizes (P80= 4.6 µm), the gold recovery for the same cyanidation conditions increased to 67%, with cyanide consumption of 66.7 kg NaCN/t. Additional tests were performed in order to reduce the cyanide consumption. The reduction of the cyanide concentration in the leaching solution from 1 to 0.5% and the addition of 100 g Pb(NO3)2/t allowed the reduction of the cyanide consumption to 27.6 kg NaCN/t (58% reduction), while maintaining the same gold recovery of 67%. The remaining gold could be present as very fine inclusions or in solid solution in the matrix.

Jan 1, 2011

By Yubo Tu, Lianqi Wei, Tianyi Zhao, Peiwei Han, Zhengchen Li, Shufeng Ye

The effect of oxygen partial pressure on the volatilization percentages of valuable metals from iron-rich pyrite cinder by chlorination-volatilization method using CaCl2 as chlorinating agent was investigated in this study. The volatile products were collected directly and analyzed by X-ray diffraction. It was found that there were CuCl2, CuCl, PbCl2, and ZnCl2 existed in the volatile products. Au and Pb volatilization percentages were almost not affected by oxygen partial pressure. Both Cu and Zn volatilization percentages were negatively correlated with oxygen partial pressure when CaCl2 dosage was no more than 4 wt%, and almost uncorrelated with oxygen partial pressure with a CaCl2 dosage of 6 wt%.

Dec 19, 2023

By P. T. Luckie

The selectivity curve -- a continuous function which predicts the expected proportion of feed material of a particular size that will appear as coarse material -- is the preferred model for describing classification. In a previous paper (I), the authors presented a technique for determining the selectivity curve of a classifier from experimental data. The separation process is defined by a binomial distribution of the form [ ] where s(x), the probability of particles of size x reporting to the coarse stream, is obviously the selectivity value for material of size x.

Jan 1, 1975

By F. J. Sotillo

Mining in Peru is mainly concentrated on metallic and polymetallic ores of gold, copper, lead, zinc, silver, tin, iron, etc. However, little has been done to develop extensive and rich non-metallic or Industrial Minerals deposits with the exception of some silica and phosphate deposits. This paper presents the characterization and metallurgical studies for the development of a feldspar deposit. These studies showed that the special characteristics of the ore, such as high porosity, high Al2O3 content, low clays content, and sized material allowed us to obtain commercial products applying relatively simple and low cost concentrating unit operations. The characterization studies showed that the feldspar products contained no quartz and about 90% of albite (NaAlSi3O8). The 14x40-mesh size fraction product analyzed 5.91% Na2O, 22.56% Al2O3, 65.73% SiO2, 0.65% K2O, 6.50% CaO, and 0.40% Fe2O3; whereas, the 40x150-mesh size fraction product analyzed 6.22% Na2O, 24.30% Al2O3, 60.80% SiO2, 0.91% K2O, 7.06% CaO, and 0.54% Fe2O3. These products could be used for manufacturing glass, ceramics, refractory, and filters in different applications. In addition, Middlings, could be used as insulation material due to its porosity (bulk density of 0.828 Kg/dm3), analyzing 4.46% Na2O, 15.7% Al2O3, 67.2% SiO2, 2.57% K2O, 3.94% CaO, and 4.24% Fe2O3. The material showed a sphericity of 0.77, a roundness of 0.68, and acid solubility of 13.3025% on only washed and 2.72% effective for clean material suitable for use in these applications. No selective accumulation of the valuable mineral was observed at any specific size fraction. However, iron and titanium bearing impurities trended to concentrate in fine fractions (minus 70 mesh -212 µm-). Metallurgical studies demonstrated that this feldspar ore required sizing at 14x40 mesh and 40x150 mesh to render commercial products. In the case of the 14x40-mesh size fraction, the process involved magnetic separation, gravity separation, and flotation for feldspar (direct flotation) using a blend of primary and condensate amines. However, the reverse flotation for mica-biotite and iron bearing minerals was also possible using petroleum sulfonate. The metallurgical process for the 40x150-mesh size fraction required magnetic separation and reverse flotation of iron and titanium bearing minerals, the feldspar being reported in the sink material. Commercial products from this feldspar deposit for glass, ceramics, refractory, and filtration; and for the manufacturing of insulation material were obtained.

Feb 23, 2014

By Jiang Shuguang, Zhang Huicheng, Wang Xingshen

Based on the experience about determination of properties of the main fan in mine shaft, this paper relates at length how to reasonablly select test system, test methods and test instruments, how to appraise the reliability of determination results, and how to effectively control the adjusted air etc. The merits and demerits of the two methods of determining air with Nine- Anemometer and Pitot meter are compared.

Jan 1, 1991

By Ronald J. Roman

A mathematical model was developed for the grinding and flotation section of Union Carbide's Bishop mill and this model was used to indicate how variations in grind, retention time, and calcite and fluorite content effects the mill capacity, tungsten units produced, and the grade and recovery of the scheelite concentrate. A model such as this is a starting point in determining the economic optimum running condition for a mining and milling operation and an example of this is given.

Jan 1, 1969

By William Gleason

During the 116th National Western Mining Conference and Exhibition in Denver, CO, the host city was often referred to as world?s mining capital, so it was fitting that the conference looked at the mining industry through a global lens. In the current world economy, the mining industry must keep a sharp focus on such things as commodity prices and global supply and demand as well as local issues that can have a dramatic impact on a mine?s social license to operate. In short, companies should mine locally but think globally. During the three-day conference at the Colorado Convention Center, a range of global and local issues that effect the industry were discussed. A record 1,144 people attended the conference.

By M. Pawlik

Canadian sylvinites contain over 90% of KCl and NaCl and a few percent of water-insoluble minerals. Cationic flotation is used to produce KCl concentrates. Since water-insoluble minerals appear in the pulp as slimes, and since long-chain primary amines are utilized as a collector, desliming is essential. The potash industry utilizes different desliming methods. This may involve selective flocculation of the slimes with polyacrylamide and removal of the flocculated product by flotation, or mechanical desliming with the use of classifying cyclones. Whichever method is applied, desliming is never complete; the flotation feed after desliming still contains about one percent of the slimes which heavily affect collector consumption and flotation selectivity. Therefore, the remaining slimes have to be rendered inactive by “blinding” them with polymers such as carboxymethyl cellulose or guar gum. The commercial blinders used by the potash industry include natural and synthetic polysaccharides. The most common is the use of carboxymethyl cellulose (CMC) and guar gum (GG). These are quite different polymers, while CMC is anionic, GG is non-ionic; while the applied CMCs are of relatively low molecular weight (about 300,000) GGs have much higher molecular weight. Guar gums are also heavily used as the depressants of naturally floatable gangue in the processing of platinum-bearing ores, and according to Harris et al. (1999) quite a large variety of modified guar gums are available in South Africa for this application. Cheng et al. (2002) claim that natural guar gum’s molecular weight is 1.935 • 106. Robinson et al. (1982) found that the molecular weights of five grades of commercial guar gums ranged from 4.4 • 105 to 16.5 • 105. The highest molecular weight sample is then very close to the natural guar gum studied by Cheng et al. (2002). According to the manufacturer, the Rantec KP4000 guar gum which is used by the Canadian potash industry has a molecular weight of about 1.5 x 106. Since both KCl and NaCl are soluble in water, the flotation process is carried out in saturated brine. At 20 oC, 1450 kg of NaCl-KCl-H2O saturated solution contains about 0.300 kg of NaCl, 0.150 kg of KCl, and 1 kg of water (Gaska et al., 1965). Thus, in the saturated NaCl-KCl brine there are about 5.1 kmole of NaCl and 2 kmole KCl per 55.5 kmole of water. This gives 3.9 molecules of water per each ion assuming complete dissociation of NaCl and KCl. Thus, it is obvious that all water molecules in the saturated brine must be bound in the hydration shells around the hydrated ions. The surface tension of the NaCl-KCl saturated brine was recently measured to be 85 mN/m (Laskowski et al., 2003).

Jan 1, 2004

By William G. Freeman

In comparison to many mineral commodities, barite has a low unit value. It is mined and sold in low volumes in high-grade (90-98% BaSO4) forms to basically one industry that uses approximately 75% of the free world production. Based upon the above criteria, all factors must be considered in determining if a barite deposit is economical; such as, the type of deposit, mining and milling methods required, transportation to the markets, tariffs, local political conditions, etc. In other words, barite mines are made--not found. The length of this paper precludes any indepth discussion of geology, mining and metallurgy of barite. Most of this information can be found in data already published, such as D. A. Brobst's bulletin1 on the Barite Resources of the United States.

Jan 1, 1971