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By H. Colin

The basic industry, such as mining, ferrous and non-ferrous, cement and aggregates, stores and handles millions of tons of raw materials, re- quiring often different types of storage, blending and reclaiming systems.

Jan 1, 1980

By Richard L. Ash

In many instances, blasting exerts the dominant control over the economics and safety of excavation, where the materials involved are too hard and tough to be fragmented efficiently by other means. However, associated with the fragmentation process other effects very often result that are not desirable and may even be hazardous, such as fly rock, air blast, excessive overbreak, and damaging ground virbrations. It has always been the desire of those concerned with blasting to better control the forces involved so as to improve the breakage of materials, but at the same time reduce, or eliminate if possible, the unwanted side effects. Until the last decade or two, little was known of the phenomena concerned with blasting. However, since that time many investigators have studied blast mechanisms produced from both chemical and nuclear explosions, with the result that general concepts of the principles have been developed. But, in general, it is assumed that the energy from the explosion would be propagated spherically throughout the material, the latter of which for convenience of analyses is considered homogeneous and isotropic, i.e., the properties are the same in all directions, However, rocks are not isotropic as a rule, and evidence clearly indicates blasting forces rarely function uniformly or in spherical form as theorized.

Jan 1, 1965

By Wern-Ping Nick Chen

Durability risks for underground facilities can be underestimated during design phase as compared to well-known geological risks. However, unclear durability requirements can result in construction schedule delay and change orders. Unlike bridges or buildings, a unified underground durability code or standard does not exist. This paper will provide a durability approach for underground facilities, including degradation modes, mitigations, and compliance measures during construction. In addition, this paper will address how to clearly specify durability requirements in a contract document to reduce disputes during construction and discuss key durability tests that are time consuming and will impact construction schedule if not timely planned.

Jun 23, 2024

By Pratima Meshram Abhilash

In this review, availability of germanium in primary and secondary resources and its recovery from these resources are presented. With nearly 40% germanium consumed in fiber optics and scarcity of resources, the global consumption outplays the primary production. Germanium exists as a substituted element in zinc sulfide matrix of lead–zinc sulfides and lignites. Nearly 60% of the germanium supply is met by zinc refining residues, and about 20–30% of germanium is produced from coal and its by-products. Germanium recovery from various resources such as zinc plant residues, coal and coal plant waste, spent optical fibers, and copper flue dust has been examined. Bioleaching was exploited by few researchers to extract germanium from zinc sulfides, sulfide tailings, jarosite, coal fly ash, and flue dust. This review covers the various work carried out by different chemical separation processes, viz., chemical precipitation, solvent extraction (SX), ion exchange (IX), and membrane processes, as well as biological approaches.

Jan 16, 2022

By S. K. Sahoo, S. K. Sharma, A. Yadav, B. Behera, G. S. P. Singh

A field representative modeling of the gob behavior is critical for the understanding of the associated mechanics of strata behavior in longwall workings. The findings of theoretical models and laboratory tests on the simulated gob material have shown the strain hardening behavior of the gob material. The double-yield material model, which is a built-in constitutive model in FLAC3D, has significant potential to simulate the gob compaction process as it represents materials which undergo irreversible compaction in addition to shear yielding. Apart from this, several researchers have attempted using modified elastic model or applied nodal force in reaction to the strain in the gob area as per the well-known theoretical relations to meet this requirement. Although these models can simulate the mechanical response of the gob for subcritical and critical extraction widths, they do not apply to supercritical extraction width as the gob stress may exceed the in situ stress level in such cases. For overcoming these limitations, a standard approach has been developed and validated in this paper, which can be used for simulating the gob behavior in supercritical longwall workings as well. The complete study is divided into two stages wherein the laboratory scale compression test on the simulated gob material has been numerically replicated to develop preliminary confidence followed by a parametric study of the double-yield constitutive parameters for a rational estimation of their values in different conditions. The calibrated model has been used for verifying its results by plane strain modeling of two different longwall workings, using well-established empirical and analytical findings and field observations. The approach suggested in this study can be used for the efficient modeling of the gob behavior of longwall panels under varying geo-mining conditions without compromising the accuracy of the numerical model. The meticulously validated model can be helpful in rational estimation of stress redistributions around the gob area apart from load transfer on the barrier pillar.

By Leslie C. Thompson

The heap leach process used for recovering gold from oxide and sulfide ores is operated as a closed circuit system in which the cyanide process solutions are continuously recy­cled. In a well-designed operation there is little or no dis­charge of cyanide to the environment. Spent leached ore residues are water washed to remove most of the trace cyan­ides and precious metals remaining after completion of cyan­ide leaching. After the washing step, small amounts of cyanide, metal-cyanide complexes and nitrates remain in the residue. Most of the cyanide and nitrate residue constituents exist in the pore water of the spent ore rather than in the solid mineral fraction. More than 90% of the complexed cyanides in a freshly washed ore residue are present as free cyanide or weakly complexed metal-cyanides. Natural volatilization and decom­position rapidly remove most of these easily dissociable cyanides from the spent ore. Only the stable, strongly com­plexed metal-cyanides, such as gold, cobalt or the ferrocyan­ides and other constituents such as nitrates have a long term persistence in the spent ore residue (Towill et al). Despite washing and natural removal mechanisms, spent ore has the potential to act as a point source of com­plexed cyanides and nitrates for soil and groundwater con­tamination if inadequately contained (Huiatt et al). The groundwater contamination is caused by the leaching of the soluble cyanide compounds and nitrates from the pore water of the residue.

Jan 1, 1990

By G. Deschenes, M. Fulton

The New Britannia Mine processes a qumtz-carbonate gold ore containing 4.63 git Au at a rate of 2,200 tpd. The ore contains approximately 3 .0% arsenopyrite, 2. 7% pyrite and the rest is gangue minerals. Eight to ten percent of the gold is refractory to leaching. Two years ago, New Britannia Mine experienced cyanidation problems. Gold extraction was not stable and occasionally decreased significantly. Preliminary test work, at laboratory scale and in the plant, indicated that lead nitrate addition was beneficial. A laboratory study was initiated to evaluate the level of control of the parmneters (grinding size, dissolved oxygen, pH, free cyanide and lead nitrate) to optimize the efficiency of the process. It was found that lead nitrate addition is required to alleviate the effect of metallic sulphides. This addition causes a significant increase in the gold leaching kinetics and a reduction in the cyanide consumption. The optimum system appeared to be: leaching for 24-30 hours at pH 11.8, 50 git lead nitrate, 250 ppm NaCN and 8 ppm 02. The gold extraction was 89.8% with grinding at 89%-74Fm (leached tail at 0.48 git). Cyanide and lime consumption are 0.40 kglt NaCN and 1.9 kglt respectively. Following the incorporation of lead nitrate, overall gold extraction was increased from 89.2% to 91.1 % but no change was noticed in cyanide consumption. The gross profit is $CDN 988,000 per year.

Jan 1, 1999

By G. Deschenes, P. J. H. Prud'homme

A laboratory study was carried out to evaluate the effect of oxygen and lead nitrate on the recovery of gold by cyanidation of a free milling gold ore, which contains 0.4 % copper as chalcopyrite. Efficient gold extraction is achieved only under specific conditions. The recovery of gold was increased from less than 90% to up to 98% by addition of lead nitrate. In the pre-leaching, the kinetics of oxidation of soluble sulphides are not an accurate indication for the length of the treatment. Even though the consumption of cyanide was reduced due to the inhibition of the dissolution of chalcopyrite by increasing additions of lead nitrate, cyanide consumption had to the held above 1.85 kg/t to maintain good recovery of gold. The continued addition of lead nitrate above 300 git had no impact on the recovery of gold. It was also found that the addition of lead nitrate at the start of cyanidation gave the same performance as when added during pre-leaching. The addition of oxygen increased the recovery of gold by 1.5%. The concentration ofNaCN had to be maintained in the range of700 mg/L because of the high concentration of copper in solution. The recovery of gold dropped significantly when the average NaCN concentration fell below 640 mg/L. Application of the findings of the laboratory study at the industrial scale led to improved plant performance.

Jan 1, 1997

By David D. Spencer

As in many other areas of the Mexican economy, the legal rules applicable to mining in Mexico have been changing fast. Mexico's mining sector is opening up to levels of international participation that were unforeseeable just a few years ago. Over the last several years, Mexico has made dramatic changes in its trade and investment policies. Many of these changes have their roots in the administrations of Miguel de la Madrid and perhaps even Jose Lopez Portillo. However, the current administration of President Carlos Salinas must be given credit for articulating, advancing, promulgating and implementing these changes. Just a few short years ago, few people believed Mexico would repeal so many of its restrictions on foreign investment and lower its average tariff level from something around 100% to less than 10%, where it is today. NAFTA and mining The North American Free Trade Agreement (NAFTA) is the most comprehensive international expression of Mexico's new policies. Except perhaps for the agreements establishing the European Union, NAFTA is the most detailed trade agreement ever written, consisting of about 2000 pages. The provisions of NAFTA with the greatest relevance to the mining industry include the chapters on investment and government procurement. Many mining companies may also find the temporary work provisions relevant. Finally, no discussion of NAFTA and the mining industry would be complete without some mention of the North American Agreement on Environmental Cooperation, the so-called Environmental Side Agreement.

Jan 1, 1994

By S. K. Kawatra, S. J. Ripke

Iron ore pellets use bentonite clay as binder at dosages from 0.5to 1.0% (10 to 20 pounds per ton) of moist iron ore concentrate. Bentonite is typically shipped hundreds of miles from Wyoming to the Lake Superior iron ore district. It is therefore best to know how effective a bentonite will be before it is shipped and used to bind concentrate into pellets. Current tests of bentonite effectiveness include: plate water absorption, methylene blue uptake, free swell, exchangeable cations, and glycolated layer expansion. However, these tests have many disadvantages: First, they only measure the ability of a bentonite to expand, disperse, or absorb, not how well it will bond. Second, most of the tests require up to 20 hours to perform. Bentonite only has a few minutes to interact within the concentrate before it is indurated (sintered). These long-term tests may not reflect the true behavior of bentonite. Third, the tests are tedious and often results are inconsistent between different iron ore concentrates, labs, and technicians. Fourth, some of the testing equipment is difficult to procure. Fifth, procedures are often difficult to standardize. In this paper, the Binder Effectiveness Strength (BESt) test to evaluate binders for iron ore pellets is presented that: measures the ability of bentonite to bond, requires only about two hours to complete, is simple and reproducible, and utilizes readily available equipment that has been standardized for decades.

Jan 1, 2003

By Ekkehart Mertins, Hans-Dieter Wasmuth

During the last years many new concepts have been presented for magnetic separation of feebly magnetic minerals by using the new high-duty permanent magnetic material especially in Open Gradient Magnet Systems (OGMS). In this respect KHD Humboldt Wedag AG developed an improved version of a drum-type magnetic separator called PERMOS® with a special magnetic field configuration for the NdFeB permanent magnets, which gives a magnetic field strength of at least 0.7 Tesla and a wide working zone outside the drum. The magnet system within the PERMOS® unit is no longer made of relatively large magnet blocks of alternating radial magnetisation; the system is now made up of a multitude of small NdFeB bars with a specially oriented magnetisation. This PERMOS® Open Gradient Magnetic Separator can be used for dry magnetic separations in "top-feed" and 'free-fall" feed configuration as well as in the conventional wet "drum-type" feed mode. It allows high throughput rates of up to 40 metric tons of solids per hour and meter of drum length without any clogging problems, even when strongly magnetic com-pounds are present in the feed material. The important design features and the actual machine characteristics of the improved PERMOS® units for dry and wet magnetic separation are described and typical examples for their commercial application for industrial minerals and for martitic iron ores are presented.

Jan 1, 1995

By B. R. Reddy, P. V. R. Bhaskara Sarma

A process for the separation and recovery of cobalt and nickel was optimized for a sulfate leach solution of Indian Ocean sea nodules containing 80 g/m3 cobalt and 730 g/m3 nickel using the sodium salt of Cyanex 272 as the extractant. Extraction of both cobalt and nickel increased with an increase in equilibrium pH and extractant concentration. The extracted species with respect to cobalt appears to be CoA2.3HA. More than 99.6% extraction of cobalt was achieved using 0.04M solvent in a three-stage counter current simulation at the A:O phase ratio of 3:2. The co-extraction of nickel was about 0.6% only. Two-stage countercurrent stripping of cobalt from the loaded organic at an A:O ratio of 1: 7 resulted in a pregnant electrolyte enriched by 0.8 kg/m3, thus enabling a ten times overall enrichment of cobalt. From the cobalt free raffinate, nickel extraction was carried out using 0.25M solvent in two countercurrent stages, and the extraction showed a 99.8% recovery. Stripping of nickel from the loaded solvent was carried out at an equal phase ratio with the advance electrolyte of pH 1.75 in two countercurrent stages. The nickel stripping efficiency was found to be 98.8%. The present studies indicated that complete recovery of cobalt and nickel was possible using nine counter-current stages.

Jan 1, 2002

By R. W. Mossman, George E. Heim

Seismic exploration techniques offer the engineer and geologist a way of obtaining detailed information on the physical parameters and geometry of the rocks where extensive underground excavation or tunneling is proposed. Use of the seismic method can provide a greater amount of detailed information at relatively less cost than can be obtained by any other known subsurface exploration method. Boreholes are still required for calibration of the seismic data but at a much wider geographic spacing than otherwise would be needed for subsurface mapping. The seismic data can define with precision the actual location of zones of flexure or fracture of the rocks and reveal the configuration of the surface of the rock layers. ENGINEERING PROBLEMS One of the major requirements in the planning of subsurface installations is that of locating tunnels and other underground openings in favorable rock units. Such rock units should exhibit uniformity of composition, both vertically and horizontally, to minimize variation in excavation techniques. The depth and thickness of the unit must be known: a 30-foot diameter tunnel cannot be contained in a 25-foot thick limestone. The rock unit needs to be as free as possible from structural defects and should be suited to efficient excavation procedures. If liquid conduits are planned, the slope of the rock unit needs to be known so that maximum advantage can be taken of gravity flow with the tunnels wholly contained within the unit.

Jan 1, 1997

By Zhongxue Li, Shuang Gao, Zhixin Zhen, Yiqing Zhao, Xuan Qin

If not well-managed, a mine-tailings facility may become a major source of risks, endangering the community and environment, and damaging the reputation of the minerals industry regarding sustainability. Identifying, characterizing, and mitigating the hazards and risks associated with tailings facilities have been critical to the maintenance of community-safe and environmentally sound mine-tailings facilities. Herein, a complex network model for characterizing the hazards and risks associated with the lifecycle of tailings facilities is presented. In this approach, the hazards are modeled as vertices of the complex network, and the interactions among the hazards are modeled as edges of the complex network. The complex network for modeling the hazard and risk spreading of mine-tailings impoundments is analyzed and characterized by using network metrics such as the network density, geometrical characteristics, characteristic path length, network efficiency, and clustering coefficient. The degree distribution of the network obeys a power-law distribution, indicating that the network for characterizing the risk spreading associated with a tailings facility is scale-free. According to the results of calculations and existing research results, the network is ultrasmall-world. By analyzing the change of the global network efficiency under four kinds of different methods to remove network nodes and edges, network nodes with higher between centrality (BC) are identified as critical. The removal of those critical nodes helps mitigate risks associated with a tailings facility and reveals the vulnerabilities to BC attacks.

Jan 1, 2017

By Lynne Chastain

The Eastern Shoshone and Northern Arapaho tribes of the Wind River Indian Reservation, Wyoming are interested in developing their industrial mineral resources. The U.S. Bureau of Indian Affairs (BIA), Division of Energy and Mineral Resources (DEMR) is assisting the tribes in evaluating the potential of their industrial mineral prospects for development. Gypsum occurs on both sides of the Owl Creek Mountains in the basal portion of the Jurassic Gypsum Springs Formation. The gypsum resources that are being evaluated crop out along the northern flank of the Owl Creek Mountains in the Sweetwater basin, a small topographic sub-basin of the Big Horn Basin. From October 1998, to April 1999, DEMR personnel mapped, sampled, and drilled the southcentral butte within the Sweetwater basin. Samples were analyzed for free and combined water, and major mineral oxides to determine gypsum purity. Gypsum purity averaged 93.6 percent for surface samples and 95.1 percent for drill core samples. The basal portion of the Gypsum Springs Formation is comprised of several beds of gypsum up to 9 feet (2.7 m) thick separated by 0.5 to 2.0 foot (0.15 to 0.61 m) thick lenses of siltstone and limestone. Overall gypsum in the formation ranges from 35 to 90 feet (11 to 27 m) in thickness. A resource of approximately 7 million short tons (st) (6.4 million metric tons [mt]) has been identified.

Jan 1, 2001

By Valcana Stoyanova

The distribution pattern, abundance variations and types of polymetallic nodules and associated megabenthic communities in area covers more than 60 000 km2 laid out in the eastern Clarion-Clipperton Zone (CCZ) is presented. Our observations are based on data from 158 boxcore stations collected during the cruise of the Interoceanmetal (IOM) in 2004 on board of RV Yuzhmorgeologiya. Although those polymetallic nodules for two decades been subject to prospecting and exploration studies carried out by IOM, the knowledge of megabenthic communities and their distribution pattern within nodule field was extremely limited. With purpose to evaluate the relationship between polymetallic nodules and associated benthic megafauna, an comparison analyze was carried out in respect to their composition, types, abundance across the studied area owing into account the local particular feature of bottom topography. It is suggested that the nodule-bearing seafloor supported more diverse fauna (higher number of morphotypes) than the nodule-free areas. Moreover, based on correlation between types of nodules and associated faunal morphotypes frequency the apparent relationship is considered. The most abundant megafaunal taxa (between 68 ? 92%) is essentially associated with the occurrence of the diagenetically growth nodules type (D-type and its D1-subtype); the role of the H and HD nodule-types was variable. In respect to the bottom topography, the highest diversity in the structure of megafaunal communities was recorded in the gently undulating plains and on the horst slopes, thus the highest nodule abundance occur on the topographic slopes.

Jan 1, 2008

By Thomas V. Falkie

Of the various critics of federal energy and minerals policy we are hearing these days--and they are legion--few make their points more vividly than our fellow SME member and eloquent spokesman for the mineral industry. Mr. Eugene Guccione. In a moment of comparative mellowness. Mr. Guccione recently characterized Washington's time-honored legislative and bureaucratic machinery as a case of "...scientific illiterates asking the incompetents to do the unnecessary." I hope the prevailing industry view of government is not quite that harsh, and yet one cannot deny that government intervention is indeed pressing in on the mineral industry with increasing force. What is happening today in Washington and in state capitols will have enormous impact--both short and long term--on the future of coal and mineral production in the United States. Symptoms of this trend are everywhere. In the first place, there is a sentiment, widely held and still spreading, that the government must become involved-- that no matter what the problem, the solution lies in more government intervention. Free enterprise versus statist, reflex reaction organizations. When it cones to regulation in the resource field, there is too often a tendency to start out by assuming guilt on the part of the mineral industry. This can lead to laws governing mineral recovery that are more punitive than constructive...laws drawn up with little research into the scientific or economic considerations involved.

Jan 1, 1975

By Stephen J. Swan

Feed-forward control (i.e. the forward flow of information in a control system ) is a simple and flexible approach to over-all control of a ball mill-rake classifier grinding circuit. The system described here uses mill power, feed rate, mill dilution water flow rate, and classifier dilution water flow rate only, to control mill load, throughput, mill solids, and classifier solids as well as classifier overflow grind. The mill load is controlled by a simple feed-back control loop, while mill solids and overflow grind are controlled within close limits by a unique non-linear feed-forward water control system. In effect the control follows a limited mathematical model of the grinding circuit. The configuration minimizes deviations in overflow grind due to changing ore conditions, but since it is open-loop, and the model is not complete, it is affected by changes in total ball charge and liner wear. These effects are fortunately gradual, and changes in the grind can usually be kept to within ± 1% of a target continuously for several days without adjustment. Control adjustments are made with feed-back from laboratory composites. This control system has won enthusiastic operator acceptance; it is easily started up and shut down; grind-outs have been eliminated along with flotation machine flooding and mill spills. Standard measurements and components are used throughout providing a trouble-free system design at a moderate cost.

Jan 1, 1970

By Robert E. Barry

For new coal-fired power plants, federal regulations require that emissions of sulfur dioxide be limited to 1.2 pounds for every million BTU'S burned. This is equivalent to coal with a sulfur content of roughly 0.7 percent for Eastern bituminous coals and roughly 0.6 percent for Western sub-bituminous coals. The states and their political subdivisions are free to apply more stringent standards and to develop implementation plans covering existing and new units. Most Western-sub-bituminous coals contain less than 1% sulfur and hence their use, in many cases, will allow a utility to meet the regulations. However, there are problems in using such coals in furnaces designed for Eastern bituminous coals, and furthermore it will take many years to open mines and provide transportation facilities to utilities which are now burning coals with a higher sulfur content. Moreover, pending federal legislation would outlaw strip mining on land to which the federal government owns the mining rights. Those utilities who, for one reason or another, intend to continue burning Eastern bituminous coals with sulfur contents in excess of 1 percent are faced with removing SO2 from the stack gases. The alternative of utilizing coal gasification where the sulfur is removed prior to burning in a power plant is still in the early stages of development. Therefore, a large number of processes are under development for SO2 control.

Jan 1, 1974

By Wallace W. Wilson

It scarcely 1s possible to read a new issue of any of the principal mining trade journals without noting some mention of a major new overseas mining venture with which one or more domestic companies are involved. These projects seem to follow a fairly consistant pattern; most are large open pit mines, with relatively low grade ore bodies but huge reserves; the total price tag will be in nine significant figures and around half or more of the total cost will be for infrastructure. West1 noted that nearly $7 billion is being invested annually for new mining projects and the expansion of existing mining ventures, in the free world. He anticipates that by the year 1975 such investments would reach the $10-11 billion annual figure, and that in the five year period 1972-76 total capital requirements can be expected to aggregate around $45 billion. The proportion of this total investment which will be financed in some manner is difficult to estimate because of the variety of available financing arrangements. West estimated that around 75% of the total capital would come from internally generated funds, with the balance from external sources. Conceivably a substantially higher percentage could be attributable to external financing, especially it the trend of recent mineral development in Canada and Australia is any criterion, and of course, including local sales of equity as a part of the package.

Jan 1, 1973