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By L. W. Beckstead

In a conventional zinc refinery plant, zinc concentrates were roasted at 950°C. The calcine was ground and leached in a series of leaching vessels using sulfuric acid. The pH in the first leaching vessel was maintained at 2.5, while the pH of the solution exiting the last vessel was about 5.4. The leached residue typically contained (in percent) 0.1 Ag, 0.2 As, 0.7 Cd, 2 Cu, 15 Fe, 10 Pb, and 15 Zn, and it was classified as hazardous material according to the EP-toxicity test. In order to make the residue non-hazardous, and to recover most of the metal values from the residue, a brine leach process was developed. The process consisted of leaching the zinc leach residue in CaCI, brine solution at pH 2 for 1 hour at 90°C. Silver extraction was about 95 percent, while lead, copper, cadmium, zinc, and iron extractions were about 80, 50, 50, 30, and less than 0.5 percent, respectively. More extreme conditions of acidity could have been used in the leaching stage to increase zinc dissolution, but iron dissolution would have significantly increased which would have complicated subsequent recovery steps. The leached and washed residue passed the EP-toxicity leach test and could be disposed as non-hazardous. Silver, copper, and lead in the leach solution were recovered by zinc cementation, while zinc and cadmium were recovered by sulfide precipitation. The resulting solution can be recycled in the process after magnesium precipitation.

Jan 1, 1993

By Richard Minnitt, Philippe Renard, Christina Dohm, Winfred Assibey-Bonsu, Matthew Aboagye, Julien Straubhaar, Mahlomola I. Mabala

The application of multiple point statistics (MPS) in oil studies has gained traction over the years; however, the use of MPS in mineral resource estimation and classification is still limited. This is despite MPS’ ability to deal with complex and heterogeneous geology better than the commonly applied two-point based methods. The availability and choice of a representative training image (TI) are often cited as the main challenge holding back MPS’ application in mining geostatistical studies. On the other hand, the general approach used in mining whereby early focus is on higher grade areas and lower grades are planned to be mined later presents a massive opportunity for the development of representative TIs. Mined-out areas provide large amounts of historical data that can be used to develop training images or training datasets that can be used to estimate in mining extension areas (often lower in grade), provided low grade areas are underpinned by similar geology analogue. This approach will enable more robust estimates in mine/pit extension areas for both high- and low-grade extensions than with traditional two-point geostatistical methods.

Jun 25, 2023

By M. B. M. Monte, M. L. Torem, E. R. Pecanha, A. G. Merma

The recent literature has unveiled the potential use of microbial strains in mineral bioprocessing. This study presents the use of a Gram-positive bacterium (Bacillus subtilis) as bioreagent for hematite flotation. The bacterium presents the ability to modify the properties of mineral surface (electrophoretic mobility and hydrophobicity). It was studied the electrokinetic behavior of hematite particles, before and after the interaction with the bacterial cells. The results revealed a shift of the isoelectric point (IEP) of the hematite after interaction with bacterial cells, suggesting a chemical adsorption mechanism. Moreover, after bacterial conditioning, the zeta potential curve of hematite presented high values in the alkaline pH range. The hematite and the bacterial surfaces presented contact angle values around 27.4° and 41.0°, respectively. According to the results, the B. subtilis strain was capable of modifying the hematite surface, and after interaction the hematite surface presented a contact angle value around 46.0°. The flotation tests were carried out in a modified Hallimond tube. The experiments revealed a significant increase in hematite flotability using the Gram-positive strain as bioreagent. The tests pointed out a maximum recovery of hematite in the presence of 600 mg/L and pH 5. Therefore, the results from this study showed the potential use of the B. subtilis strain as a biocollector for hematite flotation, and its possible application in the mineral flotation industry.

Jan 1, 2016

By John R. Goode

The fist part of this paper comprises a general discussion on refractory gold ores and their mineralogy. Processing methods now in use are reviewed and test procedures for the important methods are discussed. Factors determining the selection of a process are outlined. The paper includes a survey of production plants using pressure oxidation, roasting and biological oxidation to process refractory ore. The status of processes under development is briefly reviewed.

Jan 1, 1993

By V. Sheikhzadeh, S. M. H. Haddad, M. Saghaeian, N. Esmaeili, R. Hejazi

One of the most significant features of iron ore concentrate (pelletising feed) is the specific surface area (SSA) that affects the achievement of desirable pellet properties. There are various methods to determine this parameters and currently, the most common is the Blaine air permeability method. However, due to the simplified assumptions including spherical and identical particles and 50% bed porosity, the Blain test does not provide accurate results. In fact, these two suppositions are far from reality. In this research, comparison of SSA measurement ways are investigated, containing laser diffraction testing and Blaine air permeability, on samples with different SSA, obtained from Ball mill and high pressure grinding rolls (HPGR). The output data showed that the calculated amounts of SSA by means of laser analysis were far greater than any other one. Furthermore, in the same results of Blaine air permeability tests on samples comminuted by different grinding methods, it was observed that the SSA figures from the laser diffraction method for HPGR products were almost 800 units greater than Ball mill ones. Keywords: Pelletising feed, specific surface area, Blaine air permeability, laser diffraction testing

Jan 1, 2020

By R. Havens, B. K. Shilber

"INTRODUCTION In the course of the investigation of the occurrence of manganese deposits in the western United States, ore-dressing tests were made on three samples procured by Bureau of Mines engineers from two properties in southeastern Juah County, Utah, each of which is known by the name Black Jack. To avoid confusion, the tests will be described under the names of the owners Kendall-Duvall and the Empire Mines.None of the samples were amenable to ore dressing for the production of high-grade manganese sinter.Ores from the Kendall-Duvall deposit represent an interesting metallurgical phase of low-grade manganese occurrence, as the occurrence of manganese as silicate (braunite) automatically governs the extent to which they can be beneficiated by mechanical methods of treatment. As less than 50 percent of the total manganese was recoverable by complex methods of treatment in a 40- percent-manganese sinter, attempts were made to recover most of the manganese in a low-calcite, intermediate-grade product that might be acceptable for subsequent metallurgical treatment. By selective flotation of calcite and manganese, up to 68 percent recoveries were obtained in plus 20-percent manganese products..No encouragement can be given for successful ore-dressing of Empire ores as represented by samples received for testing, as no products were obtained that would meet minimum marketing specifications. Empire ore contained only 1 percent lime and might be high enough in grade (19 percent manganese) for direct hydrometallurgical treatment."

Nov 1, 1947

By G. Nazari

ERAMET, through its subsidiary COMILOG, have rights to a rich niobium and rare earth deposit inGabon. The Mabounié deposit, is located 50 kmfromthe town of Lambaréné, in a fairly remote location. ERAMET has been developing a process to recover value metals for several years, and approached Hatch Ltd. to design a sizeable Demonstration Plant to help them further optimize the process, and prove the flowsheet is technically viable. The process employs concentration techniques to recover an upgraded Nb/REE feed material for processing in the subsequent leach step. Rare earths and niobium are selectively leached, and subsequently precipitated. Following precipitation, rare earths undergo bulk separation and are purified to produce LRE and mixed MRE/HRE products, which will be further processed by Third Parties. This paper provides a high-level overview of the process, summarizes the motivation for a Demonstration Plant in the vicinity of the deposit, and discusses technical challenges faced during the flowsheet definition and design phase. Key challenges are focused on and summaries of the methodologies used to address each challenge, as well as the solutions to overcome the challenges, are discussed. The paper provides motivation for further process simplification and concludes with a project update.

By D. Harrington

Insofar as prevention of mine explosions is concerned, it is apparent that the coal-mining industry has profited but little from experiences during the past 15 years. The fact that explosions can be prevented if well-known preventive measures are adopted and conscientiously carried out appears to warrant the conclusion that many coal-mining people are indifferent to the hazards that may result in explosions. Although the principal burden of preventing explosions is upon the management, and much of the evident carelessness in failing to place in effect and to enforce suitable precautions, is assessable directly against management, the worker also has a very definite responsibility, and numerous explosions have resulted because of his failure to carry out his part in accepted principles of safety. The record of fatalities from mine explosions during the past 5 fiscal years has been anything but encouraging or about which coal-mining people can take pride; more men were killed by explosions (673) than were killed from the same cause during the preceding eight years combined (577). During each of the fiscal years 1942 and 1943, 152 fatalities resulted from explosions, compared to 163 during the fiscal year 1941, 206 in 1940, and only 16 in 1939.

Jan 1, 1944

By Shoukun Wei, Cong Wang, Lin Cheng, Zhiyu Qiao, Jingkui Liang, Weidong Zhuang

"The subsolidus phase relations in the Sm2O3-CeO2-CuO ternary system sintered at 1000°C in air have been investigated by X-ray powder diffraction. The system can be divided into two ternary phase regions and three binary phase regions. Solid solution Sm2-xCexCuO4-y is the only ternary phase in the system. The maximum solid solubility was confirmed to be x = 0.2. The crystal structure, oxygen content and superconductivity of the solid solution Sm2-xCexCuO4-y have been investigated.I. INTRODUCTIONAfter the first discovery of the superconducting ceramic system La-Ba -Cu-O[l] with Tc = 30 to 40K, other families of cuprate-based ceramics have been synthesized with higher critical temperature. These oxides include the R-Ba-Cu-O (R: rare earth) systems (Tc=90K or so)[2,3], the Pb-Sr-(R,Ca)-Cu-O systems (T c = 50 to 100K), the Bi-Sr-Ca-Cu-O systems (Tc=80 to 105K)[4], the T1-Ba-Ca-Cu-O systems (Tc=85 to 125K)[5], the Hg-Ba-Ca-Cu-O systems (Tc=90 to 150K)[6,7], and some others. The improvement of Tc is very rapid. The measurement of the Hall and Seebeck coefficients shows that they all are p-type superconductors. In 1989, Tokura et al.[8] discovered the superconductors R2_XCexCU04_y(R = Nd, Pr, Sm) with Tc=20 to 24K (onset) and found that the charge carrier is electron in contrast to their hole doped counterparts. This discovery increases the fundamental understanding of the cuprate-based superconductors by comparing their characteristics and mechanisms to those of the p-type superconductors.One of the outstanding features of these n-type superconductors is the difficulty in obtaining samples in good charactors, such as the difficulty in obtaining zero resistivity state in single crystal or bulk samples; the semi-conductivity of bulk samples in ordinary state (opposite to the superconducting state) and a reducing reaction involved before the superconductivity has been found[9]. Therefore, it is necessary to optimize the sample preparation of the n-type superconductors. All the n-type superconductors have been found· considerable solid solubility. The compositional variations play a governing role in the carrier doping of the superconducting phases. Also, it is vital to the ceramic processing of superconductors to identify the compatible phases in the phase diagram. Finally, there is always the possibility of finding additional compounds, both superconducting and non-superconducting, in an unexplored system."

Jan 1, 1996

By Roger J. Morrell

Disk-cutter experiments were performed on five rock types ranging in compressive strength from 9,000 psi to 27,000 psi. A specially constructed testing machine called a linear-cutter apparatus (LCA) was designed to load and traverse a free-rolling disk cutter across a sawed rock surface. The LCA was instrumented to measure the vertical and horizontal forces acting on the cutter during the run.. The ability of disk cutters to fragment rock was determined for both 60--degree and 90-degree cutting-edge angles, and relationships and regression equations were developed to predict cutter performance based on rock physical properties and applied forces,

Jan 1, 1970

By M. Wrobel, J. Hammerschmidt, M. Runkel

Fluid-bed technology is a key pyrometallurgical step for processing a vast number of ores and concentrates. Over the past 50 years, considerable research and development efforts have been made by Metso Outotec to expand the application window of this technology. This paper illustrates different processing routes where fluid-bed technology plays an important role in the production of the copper. The fluid-bed processes utilized are partial, sulfate-producing, and dead roasting. The focus of this paper considers the advantages of the dead-roasting process. This “zero waste” process can provide copper oxides, steam, electrical power, and sulfuric acid for new and existing solvent extraction–electrowinning plants. In a case where an operation is running out of oxidic ores and concentrates, fluid-bed roasting can be applied to close this gap and provide the required copper oxides in a sustainable way.

Jan 1, 2023

By A. Visnapuu

The U.S. Bureau of Mines investigated the oxidation of American Iron and Steel Institute (AISI) Type 304 stainless steel (SS) during annealing in simulated combustion products from several air-CH4 fuel ratios. Atmospheres representing air-CH4 ratios of 14:1 and 18:1 contained free 02, while atmospheres representing 10:1 air-CH, ratio did not. A Cr203 layer formed on SS samples annealed in atmospheres containing free 0, while a Cr-Fe spinel layer formed in atmospheres with no free 02. The Cr203 layer was adherent and presented a protective barrier to metal diffusion, effectively limiting oxidation of the metal substrate. The Cr-Fe spinel was not protective and allowed the diffusion of Fe through the spinel to the gas-oxide interface where it was oxidized to magnetite, which spalled from the surface. This resulted in thick scale layers on samples annealed in atmospheres containing no free 02, as compared to layers formed on samples annealed in atmospheres containing free 02. These results confirmed and explained industrial operators' observations that thick, smoky (fine spalled magnetite) scales form on SS annealed in low free-02 atmospheres, while thin protective oxide layers form on sheets in atmospheres containing free 02.

Jan 1, 2010

By C E. Woolley, H Jebaliya, J Foster

The East wall of the Kalgoorlie Consolidated Gold Mines Fimiston Open Pit (KCGM Superpit) has a history of wall instabilities impacting mining operations; the most significant of which occurred in May 2018, when more than 1 Mt of rock dislodged over six, 30 m high bench stacks and impacted the pit floor. Since 2011 approximately 1.250 Mt of material has fallen from the East wall at Fimiston Pit across three failure events (2011, 2018 and 2020). Each failure has been associated with major structures intersecting the pit walls: the Fiji Fault, the Australia East Secondary Splay Fault and the EWD3 Fault. In each instance the trigger for failure has been transient pore pressure in the pit walls. Northern Star will mine a cut back behind the failure area over a vertical distance of 180 m. Cut back mining will include the extraction of a remaining in situ wedge, which is assessed as kinematically able to fail, and a subvertical failure backscarp in Stage 1. A substantial amount of rill material from the 2018 and 2020 failures will be extracted in Stage 2. This paper presents the methodology in use to mine Stage 1 of the cut back, safely, through this potentially high-risk area, detailing the specific mining methodology employed, the controls put in place and the monitoring required. Day-to-day monitoring will be undertaken using the already installed slope stability radar and will feed into a daily assessment of activities which may be undertaken in the cut back area. Initial activities will focus on eliminating the potentially unstable wedge and vertical backscarp with use of innovative drill and blast techniques/products and the extensive use of remote capable equipment to limit personnel exposure.

Jun 22, 2022

By J. E. Brownhill

This paper does not deal with the typical start-up issues of equipment, production capacity or work force. This is a description of the challenges faced and the changes made by the project team to bring to fruition the reconstruction of Port Inland. Many honored traditions and norms had to be overturned to find the winning combination that provided the productivity, flexibility and cost necessary to survive in today's competitive minerals environment. This paper covers the innovation in terms of machinery, operations, and management philosophy that permitted the renovation and reopening of Port Inland as a commercial limestone producer in the spring of 1992. Port Inland, constructed by Inland Steel in 1930, operated as a captive source of metallurgical grade limestone for the steel industry until its closure in 1989. Located in the Upper Peninsula of Michigan on the north edge of Lake Michigan, the operations consist of a deep water port facility with crushing, screening and stockpile storage for 500,000 tons of finished product at the port. Ninety-nine percent of the stone is shipped via lake boat to ports within the Great Lakes. The operation is unique in that both metallurgical Dolomite and Limestone are produced on site. In 1930, Port Inland was at the fore front of technological advancement. It was the first major mining operation to use roller bearings and other equipment innovations. Over the 60 years of operation, Inland Steel placed emphasis on steel making technology and iron ore mining at the detriment of the limestone operation. By the early 80's, Port Inland was no longer a leading competitor. Inland Steel, unable or unwilling to spend the capital to modernize, closed the facility in the fall of 1989.

Jan 1, 1994

By M. M., Fine

In a laboratory study of grinding and classification' of silica sand, a satisfactory means of producing the medium-fine specification sand desired by producers of flint-glass containers was developed. The best procedure consisted of ball-mill grinding and double classification, which gave a properly sized sand containing less iron than the feed.

Jan 1, 1950

Explosives are used to mine coal. Any blast results in three size categories of products, namely over-, middle-, and under-size. Boulders can still be broken smaller in further operations after blasting. The under-size, for instance coal fines, negatively affects the mining efficiency. Their reduction ensures better returns. The paper concerns investigations aimed at reducing coal fines' generation. Inherent fractures are identified as one of source of fines. The discussion is therefore centered on establishing a relationship between the fracture occurrence, the explosive properties and the blast outputs evaluated in terms of the fines generated.

Jan 1, 1996

By Frederick Laist

I AM APPRECIATIVE of the honor you have done me in electing me to membership in your Society. I value the contacts with men of imagination and ideals which this implies. I am grateful for the recognition of such small contributions as I may have made, or helped to make, to the vast fund of scientific and engineering knowledge. We like to think, as we grow older, that our lives have not been purely parasitical, and that through our efforts some forward step, however small, has been taken toward improving conditions under which we live and do our work. In these days of industrial depression, we hear much criticism of our "machine age." Modern engineering, mass production, the complexity of our lives, all come in for some share of blame. The farmer is said to have been spoiled by the tractor and the gang plow, the factory worker has become a slave of the assembly conveyor, the scientific worker is no longer free but has sacrificed much of his individuality to the research organization of which he is a part. We wonder whether our work as engineers has been worth while and whether our striving after more efficient ways of doing things has been a curse to mankind rather than the boon we thought we were conferring.

Jan 1, 1932

By T. L. Johnston

A review of technical literature of the last quarter century discloses that much experimental work has been carried on in an effort to develop commercial processes for making sponge iron. In addition to the work that has been recorded, other work has been done the results of which have not been published. The degree of success or failure of these investigators does not detract from the fact that the problem has its challenging aspects and practical possibilities that encourage further investigation. The purpose of this report is to record information derived from recent experimental work that .had its 'objective the development and demonstration of one method of producing sponge iron. Work of other investigators was studied and applied wherever possible.

Jan 1, 1948

By Jurgen Weissflog

Why, where and since when using shiftable conveyors? Advantages of this equipment The ever increasing demand for bulk materials such as ore, coal, lignite, oilsand, oilshale and bauxite requires mainly an opencast operation. To exploit these materials huge amounts of overburden and partings must be transportes by means of conveyors, trucks or trains. When analyzing the various opencast mines it can be established that there exist only two basic types of mining systems, i. e., the discontinuous strip mining system as used in the USA (Fig. 1) and the continuous mining system as is commonly applied in Europe. The reason why these two mining methods have been developed parallel to and independently of each other to such a high technical standard results from the varying geological conditions of the mineral deposits.

Jan 1, 1983

By K. P. Chong

Fracture toughness of oil shale is an essential property in fragmentation to optimize particle sizes and permeability distributions in in-situ processes. Fracture mechanics of oil shale has been based on conventional fracture mechanics using notched samples and assuming the material to be isotropic and elastic. Oil shale is a layered material more accurately characterized as transversely isotropic. The senior author proposes to use a semi- circular core specimen with a center crack subjected to three point bending. Singular crack tip elements with isoparametric elements are used. The precracked semi-circular disk is modeled under displacement loading. The effect of crack length on the non-dimensionalized stress intensity factor is investigated by strain energy method, ellipse method, and stress method. Very close agreements are found. The fracture toughness is obtained by compressing the specimen in to failure. Parameters such as oil yield are investigated.

Jan 1, 1984