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By R. K. Clifford

The formation of elemental sulfur on the surface of sphalerite in aqueous systems was investigated. Hallimond tube flotation tests showed that unoxidized sphalerite did not float well without a collector. Flotation recoveries of greater than 95 percent were obtained without the use of a collector or frother after the sphalerite had been reacted with oxygen under pressure and water at pH 2.8 at room temperature. High flotation recoveries also resulted when sphalerite was reacted in acidic solutions in the presence of platinum sponge, titanium sponge, 316 stainless steel, copper turnings, or [10-5M++]. Conditions which produced high flotation recoveries of sphalerite yielded contact angles of 37° to 40° and also produced elemental sulfur. The increase in elemental sulfur on the surface of sphalerite was detected by elemental sulfur extraction with petroleum ether, electron spectroscopy for chemical analysis (ESCA), and the electron beam microprobe. The quantity of elemental sulfur formed was insufficient to be detected by infrared or Raman spectroscopy, or by the optical microscope or by the scanning electron microscope. An electrochemical type reaction for the production of elemental sulfur in acidic solutions was proposed. The cathodic reduction of oxygen was the slow step which needed to be catalyzed. A chemical type reaction which produced H2S rather than elemental sulfur was evident in non-oxidizing conditions.

Jan 1, 1974

By James B. Cathcart

Marine phosphorite deposits occur in Brazil, in the Bambui Group of late Precambrian or Early Cambrian age. The phosphorite is laminated, isoclinally folded, and is composed of black, elongated apatite pellets and quartz grains cemented by quartz and muscovite. Abundant, narrow quartz veinlets cut through the rock at right angles to the elongation direction of the pellets. The phosphorite is 0 to 80 meters thick and contains 5 to 30 percent P205. The deposit is elongate towards the northeast, and the central, thickest, and richest part is bounded by faults. Measured reserves are about 250 million tonnes that average about 13 percent P205. Preliminary testing indicates that grinding, scrubbing, and desliming will produce a material usable for fertilizer manufacture at a cost competitive with imported phosphate fertilizers.

Jan 1, 1977

A comparison of gold, platinum and sulfide ion selective electrodes was made in this investigation for determination of Eh in solutions containing sulfide ions as a model system. The comparison was made in terms of the accuracy of the measured response, response time, pH dependence, and reproducibility of measurement. In addition, the sensitivity of each electrode towards changes in sulfide ion concentration was measured in terms of the change in measured Eh per decade change in concentration of sulfide ions. On the basis of a detailed investigation of the electrode processes occurring at the surface of gold and platinum electrodes, it was postulated that within the pH range investigated these electrodes respond to changes in the hydrosulfide ion, HS-, concentration in solution. In comparison, the sulfide ion selective electrode is known to respond to changes in the sulfide ion, S-, activity in solution. Although the potentials measured with gold and platinum electrodes were mixed potentials, pretreatment procedures can be used to obtain a signal suitable for process control. For control of sulfide ions in flotation pulps, the use of a gold electrode pretreated at 1.0 V with respect to a standard hydrogen electrode is recommended.

Jan 1, 1990

By P. Dhar, H. R. Kota, M. Thornhill

A very high-grade calcite deposit located in northern Norway consists of CaCO3 ore with minor silicate and sulphide impurities. Cationic (Tallow-1,3-diaminopropane, Duomeen T) collector has been used in the purification of calcite by flotation with an aim of achieving calcite concentrate for its use in value-added products in a variety of industries. The feasibility of sulphide flotation from calcite by this cationic collector has been initially judged from Hallimond flotation and zeta potential on pure mineral systems and the results illustrate the removal of sulphide from calcite ore at neutral pH region. The adsorption mechanism of diamine on both the sulphide minerals was found to be the same by zeta potential studies. The variations in zeta potential are in good agreement with the adsorption of diamine molecular and ionic species as a function of pH. FTIR studies also showed the adsorption of diamine species in agreement with the zeta potential and Hallimond flotation results. Furthermore, the removal of sulphide impurities with selective flotation by diamine collector was performed in bench-scale flotation with the calcite ore and the results indeed showed that the calcite concentrate could meet the quality requirements for its use in the paper industry for coating and filler purposes.

By C. RAMADINI, F. NURJAMAN, A. SHOFI, B. SUHARNO

In this work, the selective reduction of lateritic nickel ore was carried out using sodium sulfate, sodium carbonate, and sodium chloride as additives. The 5 wt% of anthracite coal, which contains 60.35% of fixed carbon and 1.9% of sulfur, was used as a reductant. All raw materials were mixed homogenously prior to the pelletization process into 10–15 mm of diameter. The reduction process was carried out to 50 g of pellets at 950 °C, 1050 °C, and 1150 °C for 60 min in a muffle furnace at atmospheric pressure. It continued with a wet magnetic separation process to separate ferronickel (concentrates) and impurities (tailings). Iron and nickel grade analysis was performed using XRF, while phase transformation and microstructure were analyzed with XRD and SEM–EDS. The results showed that the sodium sulfate was superior, resulting in the highest nickel grade in concentrate, i.e., 15.06%. The sulfidation mechanism, which could inhibit the metallization of iron, effectively increased the nickel grade in concentrate than decomposition of carbonate and chloridization process. The sulfur content in the reductant also influenced the selective reduction process. It promotes more sulfidation of iron, thus increasing the nickel grade in concentrate.

Jul 7, 2021

By H. R. Coles

Test work conducted in the 6.4 and 10.52 m Aerofall Mills at the Iron Ore Company of Canada Carol Project showed that the conventionally used ?deflector?-type liners which form the basic principle of Aerofall Mill grinding did not necessarily provide the best grinding performance. A new design, using low profile liners incorporating radial ribs of a proper height, actually improved the mill throughput in the order of 9 to 20% without sacrificing grinding efficiency. In addition, the new design reduced liner weight and scrap losses, which resulted in a reduction of liner consumption by 25%. It provided better protection to the mill shell and reduced the overall maintenance cost for the mill

Jan 1, 1980

The Functional Performance Equation for ball milling circuits provides plant staff with a new means to improve circuit performance. However, successful execution of a plant project, with verifiable circuit processing performance improvements, requires a significant number of accompanying steps beyond the equation alone. In order to identify and articulate all these steps, a study with plant staff from two milling operations and a grinding media supplier was undertaken. ?Task analysis? of improving plant grinding performance was carried out. This analysis called for the development of a number of system components, and ultimately yielded a ?Plant Grinding Circuit Processing Performance Management/Improvement System.?

Feb 23, 2014

By E. Steel

The asbestifom habit is most commonly developed in certain amphiboles and chrysotile, but other minerals may also crystallize with this unususual habit, The habit may be characterized by 1) a fibril structure, single or twinned crystals of very small widths (generally less than 0.5 inn) which have gram with a common fiber axis direction but which are disoriented in the other crystallographic directions, 2) anomalous optical properties, primarily parallel extinction, 3) unusual tensile strength, 4) high aspect ratio, and 5) flexibility. In addition, there is evidence to indicate that some amphibole asbestos may have unusual surface properties.

Jan 1, 1979

By John E. Litz

Coca Mines Inc. is a medium sized company exploring for and developing precious metal properties in the Western United States. They own interests in a number of properties which contain reserves of gold and silver. The Hog Heaven property presently is under development for a combination of open pit and underground mining, followed by recovery of the silver and gold by cyanidation. Property Location The properties included within the Hog Heaven Project are located in Flathead County, northwestern Montana. The property is readily accessible by road from either Polson or Kalispell, Montana, Figure 1. [ ]

Jan 1, 1984

By Nik Sokol, Eric Sekulski, Leo Weiman-Benitez, Jon Hurt, Shrinidhi Vijayakumar, Phaidra Campbell

The Silicon Valley Clean Water (SVCW) Gravity Pipeline (GP) is the first Progressive Design Build (PDB) tunnel completed in North America. As part of the Regional Environmental Sewer Conveyance Upgrade (RESCU) Program, the tunnel is a key component to replacing and rehabilitating components of the existing conveyance system in San Mateo County, California. The GP consists of a large diameter Fiberglass Reinforced Polymer Mortar (FRPM) pipe installed inside a 4.1 m (13.5 ft) inside diameter, 5.3 km (3.3 mile) long precast concrete segmentally lined tunnel. The tunnel was constructed using a 4.6 m (15.2 ft) diameter Earth Pressure Balance (EPB) Tunnel Boring Machine (TBM) through heterogenous silts, clays and sands. Construction included two separate TBMlaunches from a centrally located access shaft, and a tunnel alignment below but in close proximity to very soft Young Bay Mud. Settlement criteria and mitigation strategies focused on protection of an existing 1.42 m (56 inch) diameter force main and adjoining structures along the alignment. This paper discusses the results of the theoretical settlement analysis versus the actual observed ground movements, while also presenting mitigation measures and adjustments made during tunneling to reduce the risks of adverse settlement.

Jun 13, 2023

By H. C. Harrell

The Tennessee Valley Authority began employing geophysical well logging for foundation investigations in October 1973. Since that time more than 3,000 holes have been evaluated for engineering purposes. The Tennessee Valley Authority has not actively used geo-physical well logging for exploration of construction materials, but we feel that much of the information derived from geophysical logs for foundation exploration is applicable to the construction materials industry. This paper will then discuss geophysical logging as applied to foundation engineering and, by implication, the feasibility of use in construction materials exploration. The use of geophysical logging and percussion drilling instead of coring has greatly expanded TVA's data acquisition capabilities and has also resulted in substantial savings in time and money. Economical boreholes are obtained through the use of large percussion track drills (Figure 1). This equipment is capable of drilling through the overburden, setting steel casing on the top of rock, and drilling the rock beneath the casing. Holes as deep as 400 feet (121.9 m) have been drilled by this method.

Jan 1, 1977

By R. A. Ynchausti

In January 1993, Pyramid Resources began implementation of a supervisory expert control system at a U.S Cu concentrator. The objective of this control system was to improve plant profitability through unit operation optimization and integration. This paper documents the key aspects of the project, including: economic and associated benefits, system architecture, concepts of implementation, process control strategies, practical aspects of implementation and conclusions. The implementation of expert control at this concentrator has resulted in an estimated benefit of $50,500 per day. This is a net result of improved tonnage, reduced reagent consumption, improved concentrate grade and reduced energy per ton produced.

Jan 1, 1995

By N. Duru, C. Nesbitt

During the cyanide leaching process, gold and silver ores that come from the transition zones, which typically contains low levels of sulfide, may produce one or more of the following reduced sulfur species: sulfide ( HS−), polysulfides ( Sn 2−), thiocyanate ( SCN−), thiosulfate ( S2O3 2−), trithionate ( S3O6 2−), tetrathionate ( S4O6 2−), pentathionate ( S5O6 2−), hexathionate ( S6O6 2−). The actual speciation of the reduced sulfur species in the circuits will primarily depend on the redox potential, pH, cyanide levels, and existing sulfur species in recycled process water, as well as the presence of other reactive metal species. The development of an accurate analytical method for sulfur species in cyanide leaching units of gold ores where sulfur speciation occurs has an important role in explaining the metal recovery deviations. This study presents the speciation of sulfur species and the development of ion chromatography method to analyze reduced sulfur species thiocyanate ( SCN−), thiosulfate ( S2O3 2−), trithionate ( S3O6 2−), tetrathionate ( S4O6 2−) in cyanide leaching circuits for gold ores. The method developed has resulted in precise quantification of target sulfur species in leach solutions. Method development and validation results were illustrated on analytical graphs containing each species’ peak number, retention time (min), type, width (min), area (mAU*s), height (mAU), and area distribution (%) of the peak.

Mar 2, 2024

By H. Huang, Y. Takasaki, R. N. Gow

"The presence of enargite (Cu3AsS4) is problematic in gold processing not only because it is environmentally hazardous due to its arsenic content but also because it is refractory, causing both cyanide and oxygen consumption to increase. Selective leaching and treatment of the arsenic would prove advantageous prior to applying conventional gold leaching methods. The reactivity of enargite samples from Butte in Montana and Quiruvilca in Peru were spectroelectrochemically studied under alkaline conditions – pH range of 8-13 – using Raman spectroscopy and cyclic voltammetry. Raman spectra of the surface were collected during and after potentially cycled voltammograms in order to determine and compare surface species against theoretical EH-pH diagrams constructed from mass-balanced thermodynamic calculations using STABCAL software. Under slightly oxidizing conditions, covellite (CuS) peaks were found in a short matter of time, above ~100mV vs. SHE for pH 9-13, suggesting arsenic leaching specifically occurred. At longer conditioning times, elemental sulfur was observed and tended to passivate the surface. The presence of elemental sulfur suggests that copper was eventually leached from the surface. By operating above pH 12, under slightly reducing conditions near -300mV vs. SHE, arsenic can be selectively leached as thioarsenate (AsS4 3-) or thiosulfate (AsO4 3-) without sulfur formation.IntroductionEnvironmental limitations on the pyrometallurgical processing of ores and concentrates bearing arsenic and other hazardous elements often outweigh those in hydrometallurgical processing, particularly when minerals like enargite (Cu3AsS4) are present. The hydrometallurgical processing of enargite-bearing materials can be broken down into two categories: the co-dissolution of arsenic and copper under acidic conditions, and the selective leaching of arsenic under alkaline conditions. The selective leaching of arsenic would preferably leave behind copperrich sulfide phases, typically chalcocite (Cu2S) and covellite (CuS), which then become more amenable to conventional copper (and gold) processing. Furthermore, selective leaching often employs sulfide (S2-), bisulfide (HS-) or polysulfides (Sx 2-) to first extract the arsenic as AsS4 3- and AsS3 3- (Delfini et al., 2003; Anderson and Twidwell, 2008; Tongamp et al., 2010a,b). However, hypochlorite leaching (Viñals et al., 2003; Curreli et al., 2005; Mihajlovic et al., 2007), ammoniacal leaching (Gajam and Raghavan, 1983), and finegrinding to mechanically activate the enargite surface (Balaz and Achimovicova, 2006) have been investigated to increase the normally slow reaction kinetics. Because gold ores are becoming more refractory due to increasing arsenic contents as a result of enargite, these methods are being examined more closely by the gold-mining industry."

Jan 1, 2015

By E. K. Albert

Computer oriented simulation techniques can be effective in the design and analysis of complex mining systems. In fact, a number of computer software products are available for mine systems simulation. While providing a useful tool for the investigation of mine planning problems, the availability of graphic output was limited or non-existent. Computer graphics is a natural extension of mine simulation methods and provides a more dramatic level of understanding and interface with an engineer. With today's high cost of venture development, the need for an easy to use but complete systems model which includes the major elements of mine planning with an interactive graphics interface has never been more apparent. In this paper, the underlying philosophy of design of an interactive interface to a complete surface mining simulation model is described. The basic structures of the surface mining system and the simulation model are discussed. The methods and algorithms used to implement the various subsystems are presented. Practical considerations of the design of displays and user interaction are illustrated, especially as they apply to the application of the package by a mining engineer. A simple example is provided to demonstrate the concepts embodied in the model and to show how a simulation is built from mine data.

Jan 1, 1984

By Sara Swiokla Korsikas, Toren Olson, Amado Guzman, Yuri O. Zepeda P

Ore agglomeration has been used as part of the heap leaching process for the last 40 years. However, industrial experience shows that the lack of a universal agglomeration standard has limited the benefits of this, otherwise, valuable unit process. The more complex the ore, in terms of the nature and relative abundance of fines (<74 μm), the more important that the agglomeration product satisfies some minimal requirements. This paper presents an agglomeration scale that identifies the quality standards for agglomerates and documents the resulting mechanical, physical, and hydraulic (hydrodynamic) behavior associated with each level on the agglomeration scale. The hydrodynamic properties of an agglomeration product are critical for the proper design of a leaching operation and, as shown in this paper, can be used to select the optimal pretreatment method for a given ore sample. Agglomeration as a unit process not only allows better conditioning of the hydrodynamic behavior of the ore but also creates an opportunity for optimized delivery of reagents to kick-start the leaching process which may ultimately improve the economic performance of leaching. Industrial case data is used to demonstrate the shortfalls associated with low-quality agglomeration and the benefits of improved agglomeration which range from enhanced porous structure (better percolation and drainage characteristics) to better metallurgical response (faster kinetics and higher metal recovery). Proper agglomeration has been used to render otherwise untreatable ores into valuable leaching resources.

Feb 9, 2024

By M. Duane Lackey

Electric drives hire done outstanding job in many-fields that are related to the mining industry. The equipment that is offered for electric-trucks was developed from the traction equipment which is used on the diesel electric locomotive. Rotating equipment available for use on electric trucks is identical in principle to that which is used on these locomotives. In as far as it is practical, similar controls are used. Another descendent of the diesel electric locomotive can be found in the oil well drilling industry, Here, locomotive traction motors and. electric controls have been modified to fit the particular requirements of the drilling industry, One 2400 H.P. diesel electric drilling rig drilled a 24,000 Ft. well in West Texas with an electrical maintenance cost in the order of 7¢ per hour This was a new rig and the costs are less than the average maintenance costs will be for the life of the equipment, Even soy since it took one (1) year to drill this well, this 7¢ per hour has real significance. Electric shovels use a similar type of electrical equipment; they too have shown real savings over the equipment they replaced. Since electric drives have done so well, in other fields, they warrant consideration for use in high horsepower, large capacity trucks.

Jan 1, 1961

By Dr. Jagdish C. Agarwal

Kennecott Copper Corporation has developed a new hydrometallurgical process for extracting nickel, copper, cobalt and molybdenum from maganese nodules. This process (KCC Cuprion Process) utilizes a reduction leach operating at atmospheric pressure in the temperature range of 45 C to 50 C and has been successfully demonstrated in a continuous pilot plant processing 800 lbs of nodule ore per day. The chemistry, basic flow sheet and operating characteristics are presented and discussed.

Jan 1, 1978

By Ritika Kundu, Moussa Wone, Amanda M. Morgan, Tatiana K. Proctor

The Piney Branch CSO 049 Storage Tunnel (PBST) will be the last major project for the DC Clean Rivers Program. The project includes construction of a 2,200-foot-long, 18-foot-internal-diameter storage tunnel; two connections to combined sewer infrastructure; and two shafts. Major challenges include excavation underneath an existing live outfall that must remain in service; excavation of the tunnel through several areas of low rock cover and mixed-face conditions; and negotiations with a variety of federal, regional, and local stakeholders to address project impacts. This paper describes the overall project scope; geotechnical conditions along the alignment; design and construction challenges; and construction procurement.

Jun 23, 2024

By P. J. M. van Heteren

The flotation system is usually distinguished from other physical chemical systems by the importance of interactions at the solid-liquid and solid-gas interfaces. In recent years, numerous quantitative studies have been made of the distribution of common collectors between the solid and aqueous solution phase. Although in flotation the main emphasis is placed on the adsorption process, chemical reactions will also take place in the bulk solution phase, These side reactions are often undesirable and will contribute towards the complex behavior of many a flotation system In sulfide flotation, the precipitation of insoluble base metal xanthates is a well-known phenomenon although the conditions under which the precipitation reaction will proceed and the magnitude of the solubility products are not known with accuracy. A knowledge of the solubility of these xanthate salts will not only be of value in flotation research, but the mill operator might be interested in knowing whether precipitation of metal xanthate can be controlled or completely prevented in the flotation circuit thereby reducing reagent consumption, For these various reasons the solubility of lead, copper, zinc, and silver ethyl xanthate was determined. The experimental techniques and results will be discussed in this paper.

Jan 1, 1958