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By T. Yue, Z. Gao, X. Tong, R. Liu

"Lead ions (lead nitrate) were introduced to modify the surface properties of scheelite, effectively and selectively improving the flotability of scheelite, with benzohydroxamic acid (BHA) serving as the collector. A series of experiments about the mode of addition and the ratio of lead ion to BHA were conducted and indicated Pb-BHA complexes were the active species responsible for the flotation. And two adsorption models of BHA on the surface of scheelite were established. For both the two adding methods, some kind of complexes formed by lead ions and BHA played a key role in the flotation process. Zeta potential, FTIR, and XPS studies indicated that the adsorption amount and intensity of BHA on the surface of scheetlie were larger by adding the reagents as a mixture. The mixed addition is conducive to form Pb-BHA complexes and improve the adsorption efficiency of BHA on the surface of scheelite, as well as the recovery of scheelite. INTRODUCTION Scheelite, as an important tungsten-bearing mineral, is nowadays utilized mainly by flotation (YIN and WANG, 2014; Sun et al., 2011; Gao et al., 2015; Gao et al., 2015). Flotation separation of scheelite from calcium minerals creates difficulties because of the existence of the same cation in the minerals and similar physico-chemical characteristics such as solubility, hardness, specific gravity, point of zero charge (PZC), etc. (Arnold and Warren, 1974; Deng et al., 2016; Deng et al., 2015; Ozcan and Bulutcu, 1993a; Yongxin and Changgen, 1983). The conventional collectors used in the flotation of scheelite ores are generally fatty acids or fatty acid derivatives (Bo et al., 2015; Oliveira and Sampaio, 1988; Shi et al., 2014; Sivamohan, 1988; Yongxin and Changgen, 1983). It is difficult to separate scheelite, especially from calcite, with these reagents because the adsorption mechanism of these collectors occurs through chemisorption of the oleate ion onto the mineral surface (Atademir et al., 1979; Changgen and Yongxin, 1983; Hiçyìlmaz et al., 1993; Hu et al., 2011). Therefore, it is almost impossible to separate them by fatty acid flotation without using any selective depressant. Although oleoyl sarcosine was used as a selective collector in the flotation of fluorite and siliceous scheelite ores (Ozcan and Bulutcu, 1993b; Ozcan et al., 1994), this selectivity is inadequate for a low-grade calcitic scheelite ore. Unfortunately, reagents such as organic colloids (dextrine, starch), quebracho, sodium phosphates, sodium silicate solutions containing polyvalent cations (hydrosols), etc. (Bo et al., 2015; Schubert et al., 1990; Shi et al., 2014; Yongxin and Changgen, 1983), used for calcite depression also depress scheelite to a large extent. Cationic collectors, such as amine and quarternary ammonium (Yang et al., 2015) and collector mixture (Gao et al., 2015) have been used to improve the scheelite flotation. However they have not been applied in industry due to the poor separation from silicate minerals."

Jan 1, 2017

By A. Fuerst

This paper delivers insights into how high availability combines with high efficiency at the Yanacocha Plant, Newmont Mining Corporation, Peru. Advances in motor design and maintenance with integration of smart control support the approach plant maintenance staff is applying to deliver such excellent results for availability and efficiency in Yanacocha and elsewhere. Detailed efficiency and availability data for 2011 and 2012 in Yanacocha are provided. ABB and Yanacocha teams collaborate closely by combining their experience and continuous development of gearless mill drive procedures and maintenance knowledge to deliver the impressive performance being achieved. The secrets for high performance shared by the Yanacocha maintenance operations point to their systematic, practical adherence to modern asset management and maintenance concepts.

Feb 27, 2013

By M. S. Celik

Unlike most other minerals, electrokinetic measurements of calcium montmodonite (a clay mineral) and u1exite (a boron mineral) exhibit an unusual behavior. While the addition of monovalent salts such as NaCI and KCI is expected to compress the electrical double layer with a resultant less absolute charge, an opposite trend is observed. A set of systematic experiments with monovalent and multivalent ions has been carried out to understand the mechanism of this phenomenon Examination of the results reveals that the behavior of montmorillonite is dictated by the exchangeable divalent cations at the edges which undergo an exchange process with monovalent cations resulting in the reduction of positive charges. The solubility of ulexite, on the other hand, is found to decrease with increasing monovalent cation concentration leading to again an increase in the absolute negative charge.

Jan 1, 1996

By M Aboagye, K Appau, W. Assibey-Bonsu, C. Muller

A case study based on two recoverable resource modelling techniques (indirect and direct or localised methods) have been derived using typical feasibility study or new mine drilling data configurations from the extensions of an existing mine’s massive production database. The database is from the Gold Fields Tarkwa Gold mine (~6Moz Mineral Reserves and 13-year Life-of mine). The corresponding recoverable resources from the various techniques are then analysed using the open pit Whittle optimisation process. The results were then compared based on the Whittle optimisation results to determine the efficiencies of the approaches and the validity of the recoverable mineral resource estimates for mine planning and financial forecasts (including Cash Flows etc). Based on historical production metal recovery, the paper also assesses the corresponding orebody and mine planning as well as financial risks with regards to the modelling techniques. The study shows that the localized direct and somewhat more straight forward approach if applied efficiently can provide an equally useful tool for computing recoverable resources for mine planning and financial forecasts, as compared to the indirect approach as presently in use.

Jun 25, 2023

By Jie Li, Longxiang Li, Wenbing Guo, Gaobo Zhao, Yuhang Hu

Surface subsidence caused by underground longwall mining is a very complicated process in time and space, influencing building and structures on the surface of the mining area, including houses, pipelines, and highway. The field monitoring data of surface subsidence are essential for protecting them. This study investigated the dynamic and residual subsidence characteristics of both the surface and the highway over a 730-day monitoring period on a longwall panel. Three monitoring lines (Lines 1–3) were established to monitor the subsidence process, and three stages were identified: initial stage of surface subsidence, active period of surface subsidence, and residual subsidence deformation stage. The maximum subsidence value on the highway (1,786 mm) was smaller than that on the surface (2,094 mm), and the maximum subsidence velocity on the highway (41.7–50.8 mm/day) was also lower than that on the surface (66.7 mm/day). During the residual subsidence deformation stage, both the surface and highway subsidence velocities decreased to below 0.6 mm/day. Furthermore, differences in subsidence characteristics between the surface and the highway were analyzed, with the subsidence value on the highway always being less than that on the surface, while the subsidence velocity during the residual deformation stage was not always lower. This could be attributed to the influence of dynamic loads from vehicles, which could induce additional residual subsidence on the highway. Further investigation into this phenomenon will be conducted in future research.

Jul 1, 2023

By Sidney A. Suhler

The persistent requirement for methods and equipment capable of detecting hazardous anomalies in advance of underground mining has led to the development by the U.S. Bureau of Mines of a directional radar probe. The probe operates from boreholes drilled from the surface into the underground region to be mined. The engineering model radar was completed in early 1982 and field demonstration tests were performed in May of that year at a selected coal mine. Preliminary in-situ electromagnetic tests were performed at several candidate coal mines to evaluate the radio-frequency characteristics of the coal. A coal mine in New Mexico was selected on the basis of low EM propagation losses in the coal and the presence of an extensive coal seam displacing fault as a radar target. The borehole radar was operated in two vertical boreholes which intersected the coal seam at approximately 25 and 40 feet from the fault interface. Radar reflections from the coal/ rock interface were detected in both tests. Underground tests in a horizontal borehole in the coal were less successful because of interfering reflections. Additional borehole-to-borehole tests were performed with a separate ground penetrating electromagnetic system to obtain radar range calibration data. The coal was found to be bounded by very lossy roof and floor sandstone and shale while propagation through the coal seam was obtained at distances up to 175 feet between test boreholes. Coal seam continuity was indicated by the hole-to-hole experiments through a section of the seam previously thought to be completely cut off by the fault.

Jan 1, 1983

By George A. Snyder

The presence of moderate to high concentrations of colloidal clays in coal preparation plant waters can cause serious operating and economic problems for a coal company. Among the host of possible problems are the following: 1) Poor separation of clays in the plant thickener, resulting in: a) Increased ash in the clean coal. b) Increased specific gravity of the wash water and decreased coal recoveries at the desired quality. c) Increased thickener operating costs in trying to overcome the problem. 2) Decreased solid concentrations in the thickener underflow and increased pumping requirements to meet solids withdrawal requirements.

Jan 1, 1979

Microorganisms have been widely used for hydrometallurgical operation and effluent treatments(Smith, et. al., 1991a; Gadd, et. al., 1986; Darnall, 1986; Paponettis, et. al., 1991; Mihaylov, et. al., 1991; Rusin, et. al., 1991; Noble, et. al., 1991; Yang, et. al., 1991). In recent years there is a growing interest in using microorganism for flocculation of minerals fines and flotation collector (Smith, et. al., 1991b, 1991c; Misra, et. al., 1991a, 1991b, 1992a, 1992b). It is envisioned that the utilization of nonpathogenic microorganism and/or extracellular surfactant derived from microorganism as a flotation collector will replace some of the environmentally toxic flotation collectors and at the sometime improve flotation efficiency. The selection screening, and judicious selection of appropriate microorganism as flotation collector has been a challenge to process engineers. Over the past five years, continued research at the University of Nevada has shown that certain microorganism Mycobacterium phlei (M. phlei) can be a good flocculating agent and has potential to be used as a flotation collector (Dubel, et. al., 1992; Misra, et. al., 1991a, 1991b, 1992a, 1992b; Smith, et. al., 1991d; Chen, et. al., 1992a, 1992b)).

Jan 1, 1993

By Thomas E. Browne

The Electric Power Research Institute Energy Supply Program is developing coal supply forecasts. By coal supply forecasts I mean the future relationships between coal price and production levels. A representative supply curve is shown in Figure l. It will make the rest of my presentation clearer if at this point I give you some background about EPRI and the Energy Supply Program. EPRI is funded by the nation's electric utility industry to develop new technologies for the production and conservation of electricity. Most of the research is conducted by outside contractors. We participate in joint projects with the Department of Energy and other organizations. The Energy Supply Program is one of three "economic" programs. The other two are Energy Demand and Conservation, and Systems. The Systems Program's main function is to provide the means to integrate the output of the other two Programs. The primary function of the "economic" programs is to provide information pertaining to future energy prices, availability, requirements, etc. to the EPRI personnel planning R&D programs. A secondary role that is becoming more and more important is providing information of direct use to the electric utility industry. I should note that the results of all EPRI's contract work are available to the general public. A "Coal Supply Analysis System" is being developed for EPRI by Charles River Associates. To the extent possible it will draw upon existing work, but much additional work needs to be done in the area of coal supply economics.

Jan 1, 1977

By Charles G. Zink

Anthracite is widely known as a domestic or space heating fuel. The prevailing market ratio of domestic to industrial consumption was about 80 to 20 up until 1950. Since then it has been shifting until now the ratio index is about 50/50, exclusive of overseas export. Despite a declining domestic space heating market, the demand for industrial anthracite remains good. However, as a result of stringent air pollution regulations, there is a renewed interest in this low sulphur coal which cannot smoke under any conditions. Anthracite serves other important industries such as power generating, metallurgical, cement, ceramic, chemical, water sewage and industrial wastes filtration. Anthracite is an excellent natural source of carbon and may be utilized in many processes.

Jan 1, 1966

By L. M. Cenegy

The formation of scale is common in gold ore processing plants. A working definition of scale, applicable to the various scaling conditions found in gold ore processing plants, would be: "a hard, tightly adhering deposit formed in place by the precipitation of calcium-bearing mineral compounds from water". The most common scale found in gold processing plants is calcium carbonate (CaCO3) although calcium sulfate (CaSO4) is occasionally a problem.

Jan 1, 1990

By S. Dereski, G. Chancellor

"INTRODUCTION Barrick Goldstrike underground mine is located in Northern Nevada on the Carlin trend. The underground mine produces approximately 1.5 to 1.8 million tons a year and approximately 400,000 ounces of gold a year. The mine is comprised of two main mining methods, underhand drift and fill and long hole stopeing. The mass blast project stated in 2012 as Value in Use project between Barrick, Southwest Energy and Orica, the goal of this project is to be able to blast an entire drilled stope in one blasting event instead of taking multiple blasts. This will improve productivity by eliminating intermediate blasts, reducing additional blast time, eliminate drill hole cleaning due to the previous blast. Project implantation started in the fourth quarter of 2013 and mass blasting has been common practice throughout all of 2014. STOPPING PRACTICE AT GOLDSTRIKE BEFORE MASS BLAST PROJECT The production from the Goldstrike mine is approximately 70% from stopes. The timely completion of all stoping blocks is imperative to maintaining the plan, delays in the execution of any particular block can have detrimental ripple down effects as neighbouring stoping blocks become delayed. Before the implementation of this project the standard practice for Goldstrike was to: 1. Drill the entire stope 2. Blast a bottom shot, normally between 10 feet and 20 feet off the bottom of the slot rings. This would be mucked out before the next shot 3. Blast a pull through shot, this included the raise and one or two production rings. Again mucking this out before the next shot 4. Blast production rings, one or two more blasts depending on stope size. In most cases between each of these blasts the holes in the other rings of the stope would have to be cleaned. This meant either cleaning manually using air and water, or mechanically cleaning with a bench drill. In many cases this resulted in delays in completing the stoping block."

Jan 1, 2015

By E. S. Forbus

A process for producing reductive bleach in-situ in kaolin slurries has been developed. The bleach is formed by mixing an iron sponge powder (-325M) with slurry treated with SO2. The process has been successfully demonstrated in production, and applied to several grades. The color, brightness, and viscosity of the bleached product is equivalent to or better than that of product bleached with commercial sodium hydrosulfite . The tested products can be bleached at a cost, which is 38-54% of those associated with the use of commercial bleach.

Jan 1, 1993

By Andrew Burton, Damian Schofield, Jeremy Noond

This paper will introduce and discuss a range of techniques that utilise new developments in Computer Graphics (CG) and Virtual Reality (VR) for the investigation of incidents and accidents in mining environments. The future of mining safety may not be totally led by the demands of the mine operators, but sometimes by the academics, commercial software developers and legal pioneers who generate new ideas and products and set admissibility precedents which may change the way certain traditional investigative operations are performed. In any accident investigation the outcome from the investigating team is often a complex affair and the results of the investigation are often reported in large, convoluted documents. Computer-generated forensic reconstructions allow investigators to present accident scenarios in an accessible and easily understood, visual manner. Surveys in the US have also shown that people have increased recall of computer-generated images over many other forms of evidence. The AIMS Research Unit in the UK have been pioneering the use of Computer Graphics (CG) and Virtual Reality (VR) technology for both industrial and road traffic accident reconstruction. This paper and accompanying presentation will contain examples of forensic reconstructions developed by the authors that explain some of the methodologies used to ensure admissibility of this type of digital evidence. The paper will contain a number of case studies based on UK and International industrial accidents. The paper will focus on how AIMS Research is extending the capabilities of the accident reconstructions created to take advantage of the latest developments in VR technology. As digital technology makes its impact within professional and commercial fields, computer generated forensic reconstructions will form important admissible evidence in the courtrooms of the future. The technology will also make a great impact in the way we train our workforces, with highly visual three-dimensional (3D) interactive training tools becoming the norm. Acceptance by the public, courts and workforce is an important issue, and implementation strategies must be considered carefully.

Jan 1, 2002

By T. Harris

Exports of crude gypsum from Mexico currently comprise about 60% of all domestic shipments, and about 25% of the imported material consumed in the U.S. wallboard industry. However, of growing importance are the domestic markets for calcined gypsum in Mexico including building plasters and wallboard, which account for 55% of the internal demand for natural mined material. This paper will examine the current trends in the production and trade of natural mined gypsum in Mexico and North America and the opportunities and threats that are facing existing and new suppliers in this changing market.

Jan 1, 1996

By H. Akgun

Design of plugs for abandonment of boreholes and shafts may be governed by the bond strength between the plug and host rock. This paper presents the results of push-out tests on cement grout plugs in salt. Two expandable cement grouts have been tested. The average interface shear strengths ranged from 2 to 12 MPa. Peak shear stresses at failure, assuming an elastic stress distribution along the interface, were up to eight times higher. Standard deviations commonly reached 20%. Dissolution along the interface was observed, and may have been enhanced by clay inclusions in the salt. This dissolution appears to have reduced bond strengths. Application of the results to the design of plugs for larger openings (e.g. shafts, drifts, or boreholes) is discussed.

Jan 1, 1991

By Tom Learmont

The importance of coal in solving our energy problems has been widely discussed; the world demand for food requires increased fertilizer production and the minerals to produce fertilizer must be mined. We have seen an explosive increase in the demand for large stripping equipment. It is appropriate that we review this equipment and determine what can be done to improve productivity. While we have used coal mining as an example in the study, much of the discussion will apply equally to other forms of stripping.

Jan 1, 1975

By Shingo Morimoto, Toru Sasaki, Masato Shinji

"1. INTRODUCTIONTunnel face stability is one of the most important consideration in New Austrian Tunneling Method. In general, if all of the material properties of ground can be obtained through the field investigations, the tunnel face behavior can be predicted using numerical simulation prior to tunnel construction. However, estimating the safety of a tunnel face is difficult, especially in cases where the ground is very weak such as in an urban area.In this study, numerical analyses of tunnel excavation in very weak ground conditions, such as a low cohesion and low internal friction angle, were carried out. The relationship between the average shear strain distribution on the tunnel face and the overburden was analyzed. This relationship estimates the shear strain of the tunnel face relative to the critical shear strain obtained by the ground properties. The critical shear strain was defined as an allowable value for the maximum shear strain. We proposed the allowable overburden as tunnel face stability index (TFI) that satisfies the critical shear strain criterion of ground. Finally, a design chart of the allowable overburden for various cohesion values and friction angles of ground was created. This chart is useful in the preliminary tunnel design stage to judge the necessity of additional counter measures against normal tunnel support design.2. WEAK GROUND MODELING AND ANALYSIS PROCEDURE2.1 Setting material propertiesWith reference to a past study1), the material properties were adopted on the basis of material properties in the standard worst rock classification case called “DII”2) for standard support pattern of weak ground in Japan. The typical material properties for “DII” are listed in Table 1. In addition, Fig.1 shows the distribution of the representative weak ground according to cohesion and internal friction angle. When the internal friction angle is relatively high and the cohesion is weak, the ground is categorized as sandy ground. Furthermore, when the internal friction angle is low and the cohesion is strong, the ground is categorized as clayey ground."

Jan 1, 2016

By C. R. Pelley

This paper is intended to describe the utilization of Western subbituminous coal as used in a utility-sized steam generator. It compares this coal's characteristics with those of a typical Midwestern and Eastern coal as a base and reviews the various design considerations when blends of these coals are used. The effects of blending various low-sulfur Western coals with Midwestern or Eastern coals to achieve a predetermined sulfur dioxide emission and the resulting alteration in the coal characteristics as they apply to utilization are also reviewed. The blending of coals as one means of complying with sulfur dioxide regulations will take on increasing importance as the various deadlines for compliance with new and existing regulations approach. We must first consider the availability of these low-sulfur coals; and insofar as the Eastern low-sulfur coals have been mined for many years, we have focused our attention on the availability of the coal reserves west of the Mississippi River in the United States, as this is the area to which many people are turning in order to meet this requirement.

Jan 1, 1976

By S. A. Sass

The design and construction of Solvay Minerals (formerly Tenneco Minerals) Soda Ash Expansion Project, which is the world's most modern natural soda ash facility, is detailed. Along with a discussion of design considerations, the international joint venture ownership and teaming arrangement for design and construction companies is examined.

Jan 1, 1994