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By Prescott Greene

AVAILABLE MACHINES Machines discussed in this section include only rubber tire mounted kerf cutting machines of a self¬propelled electrically powered design. Such machines handle bars up to 4.6 m (15 ft) in length, cutting kerfs of from 115 to 191 mm (4.5 to 7.5 in.). The basic design concept of all machines currently in production is very similar. The chassis features dual driving wheels on the cutter-bar end, fixed directly to the main frame. The steering wheels on the outby end of the frame are articulated in some manner to keep all four wheels on the floor over uneven bottom. Machine power for tramming, and all other functions except powering the cutting chain, is furnished from a pump motor that drives the specific pump or pumps required by a given machine. The cutter chain is driven through a mechanical drive train from a separate electric motor having no duty other than driving the chain. The general arrangement of a cutting machine is shown in Fig. 1; two types of machines, with their specifications are shown in Figs. 2 through 5. A hydraulically powered cable normally is included to eliminate the need for manual cable handling and make this a one-man machine. A bug duster, though optional, is needed for most applications. The bug duster is an hydraulically driven scroll conveyor located directly behind the cutter chain drive sprocket. Its function is to move the cuttings away from the sprocket to prevent them from packing up in this area and consuming a lot of machine power to further pulverize them. Available machines vary from models 610 mm (24 in.) high that can cut horizontally only from 203 mm (8 in.) below ground line to 229 mm (9 in.) above, to machines 1143 mm (45 in.) high that can cut in any plane from 178 mm (7 in.) below the ground line to 3.7 m (12 ft) above it. Most currently manufactured machines fall in the 17 200 to 20 400 kg (38,000 to 45,000 lb) weight range, but can be dis¬assembled for underground installation where weight and size are a problem. Maximum teardown results in all pieces having a weight of 5400 kg (12,000 lb) or less and a size allowing passage through a 1.2 x 2.1-m (4x7-ft) opening. Further reduction in either size or weight of the parts becomes a serious problem. Machines currently being manufactured are avail¬able for use with power supplies of 250 v dc; 500 v dc; 440, 550, or 950 v ac (60 Hz). Also available are machines for use on 415, 500, and 950 v 50 Hz. De¬signs to allow operation on other voltages of either 50 or 60 Hz can be made available without any serious problems. As of September 1977, a typical medium-seam ma¬chine without the extra options needed for unusual conditions, but fully equipped to operate, was selling for about $185,000. CAPABILITIES Materials That Can Be Cut The problem of deciding before a machine is put on the job whether it can work effectively is an old one that has never been completely solved and probably

Jan 1, 1982

Twelve years ago, Jeffrey Mining Machinery Division of Dresser Industries Inc. developed the 120H HELIMINER. This machine was the world's first fixed-drum continuous miner and soon became the standard among manufacturers of continuous miners throughout the mining machinery industry. This paper will first outline a brief history of continuous miner development, then discuss significant parameters which are essential to a successful continuous miner design, and finally describe a number of specific applications of Jeffrey continuous miners in a variety of materials, such as coal, potash, iron ore, and trona, around the world.

Jan 1, 1978

By A. W. Khair

This paper deals with the evaluation of the interaction between rock and the cutting tool, and with methods for determination of workability, and abrasivity of rock. A description of instrumentation is included along with research on the wearing process of bit tips and pick consumption. Analyses of bit rotation, evaluation of cutting, normal forces and energy consumption is presented. Finally influence of the basic water jet parameters and water jet assistance on the cutting process of hard and abrasive sandstone is discussed.

Jan 1, 1995

Cutting strong rock with a drag bit assisted by high-pressure water jets By M. HOOD. B.Sc. Hons. (Min. Eng.). B.Sc. (Mech. Eng.). A.M.I.M.M. (Visitor) Experiments are described that led to the discovery that coherent high-pressure water jets directed immediately ahead of drag bits while they are cutting strong rock reduce the magnitudes of the forces on the bits significantly. Tests were carried out to assess the effects of the pressure of the water jets on bit-cutting performance. The pressure was varied between 10 MPa and 50 MPa, the water flow rate being a constant 30 I/min. Over this pressure range, the force on the bit was reduced to the extent that the depth of cut of the bit was at least doubled with the point of impingement of the jets optimized. Forces on the bit were found to be particularly sensitive to the point of impingement of the water jets relative to the bit. The optimum configuration was found to be with two jets, one directed towards each corner of the bit and impinging on the rock approximately 2 mm ahead of the leading edge of the bit. Experiments in which a drag bit and high-pressure water jets were used to cut strong abrasive quartzite in the underground mining situation have demonstrated a potential increase of up to five times in the average depth of cut due to reduction of the forces on the bit. The results from the underground tests indicate that the life of the bit is improved significantly - by a factor of approximately two - when highpressure water jets are used.

Jan 11, 1976

By David G. Abbott, Frank Coluccio

This paper will discuss the construction of nearly 165 m (540 ft) of 3.5. m (138 in) o.d. reinforced concrete pipe to replace an existing utilidor under the Duwamish River in Seattle, Wash. The project required that two 27.4 m (90 ft) deep shafts be installed for use as jacking and reception shafts during the tunneling operation, and permanent vaults once completed. Soil conditions to be excavated consisted of soft saturated sand and silt with a 21.3 m (70 ft) water head. This required the shafts to be constructed using ground freezing techniques and the tunnel installed by pipe jacking, using a Mechanical Earth Pressure Counter Balance (MEPCB) slurry shield. The original utilidor was constructed between 1924 and 1925, and has since been deliberately flooded because it is considered to be structurally unsound.

Jan 1, 1995

By Robert J. Evans

An in-seam tester, which is a hydraulically activated single-pick instrument to measure and record pick cutting forces, was designed and fabricated to establish criteria necessary for the design and development of a water-jet-assisted rotary drum cutting system using moderate-pressure jets (3,000 to 10,000 psi). Data are presented for cutting trials in a simulated coal block and underground in the Pittsburgh coal seam for water-jet assist and dry cutting. Data analysis indicates that water-jet assist significantly reduces pick forces.

Jan 1, 1984

By A. V. Kozub, D. O. Sharkovsky, R. I. Ismagilov

"Due to complex mineral composition and fine ingrained nature concentration of iron ores deposited in Mikhailovskoye mine field requires application of wet magnetic separation to produce 65–66% Fetotal and 8.2–8.6 %SiO2, concentrate with 90–94% of material being –0.044micron grain size. Higher specific consumption of ROM, increase of production costs with concurrent reduction of output - those are inevitable side effects of desired concentrate grade improvement. Large-scale complex analysis and surveys have been carried out aimed at concentrate grade improvement with concurrent output increase. Classification of feed in hydraulic cyclones (hereinafter referred to as hydrocyclones) has been the bottleneck for improvement of processing throughput and concentrate output. Hydrocyclone classification efficiency is 50-60% and further improvement is practically impossible. Actual circulating load may achieve as much as 500-600% while the optimal rate is 200-250%. Application of wet fine screening has been considered to improve iron ore concentrate grade. Objective of this work is to design processing flow diagram for unoxidized ferruginous quartzites with implementation of wet fine screening. Large-scale tests have been run in Crushing and Concentrating Plant with application of wet fine screening stage. These tests included application of wet fine screening in 2 and 3 stages of classification to separate desired grain sized material; replacement of hydrocyclone classification with fine screening; application of fine screening as additional stages to concentration process and screening of final concentrate. Testing Methods. EXPERIMENTS AS WELL AS THEORETICAL RESEARCH HAVE BEEN APPLIED FOR THE PURPOSES OF THIS WORK; INCLUDING MAGNETIC, GRAIN-SIZE AND CHEMICAL ANALYSIS OF CONCENTRATION PRODUCTS. MODERN ANALYTICAL DATABASE HAS BEEN APPLIED TO STUDY WET FINE SCREENING FEATURES, MINERAL AND PHYSICAL COMPOSITION OF CONCENTRATION PRODUCTS. Work Results: - analysis of wet fine screening application for iron ore concentration. - technological solutions enabling to improve slurry classification of fine ingrained low magnetic iron ore have been developed. - effective process flow diagram including fine screening has been designed based on the feasible and reasonable arrangement solutions."

Jan 1, 2018

By R. J. Beltrame

The Cuyuna range, located in east-central Minnesota, consists of a sequence of argillite, siltstone, iron-formation, graywacke, slate, and quartzite of early Proterozoic age. Manganese-bearing materials occur within the iron-rich strata of the Trommald Formation and the Rabbit Lake Formation. Computer-assisted resource estimates, based on exploration drill hole information, indicate that the Cuyuna range contains a minimum of 176 million metric tons (Mt) of marginally economic manganiferous rock with an average grade of 10.50 weight percent manganese. The calculated 18.5 Mt of manganese on the Cuyuna range could supply this country's needs for this important and strategic metal for 16 years. An additional resource of 6.9 Mt of manganese metal is available in the lower grade deposits. The majority of these calculated resources are extractable by current surface mining techniques.

Jan 1, 1981

By R Linares

For centuries, diamond's superlative properties have earned it a reputation as the 'dream' material for mankind in its search to create advanced applications. Until recently, this dream has been realized only in the use of diamond for gemstones and abrasive applications where several tons of diamonds are now used on an annual basis. The vision of having large, high quality diamond as part of a broad engineering tool-kit for many diverse high tech industries is now becoming a reality however, with the advent of early stage commercial availability of single crystal and poly crystalline CVD diamond.

Jan 1, 2010

By Marco Olper

After two years of extensive research a new and innovative modification to the CX-EW process has been exploited. This process, called CX-EWS, avoids completely all the critical aspects of the previous process which affected the cost of the energy, of the chemicals and of The maintenance of the insoluble anodes. All these benefits reflect a saving of about 30% of The operating costs compared to the present traditional production and allow for a total operating costs of less than 6.5 cts/lb. lead (net of raw material cost). With this new technology it is allowed for the first time the treatment in the same plant facilities of both primary lead sulphide concentrate and spent batteries. The paper describes the technical and economical aspect of the new process with a feasibility study for 150,000 t/y spent battery facility throughput.

Jan 1, 1995

By A. Hussain

PAPER NOT SUBMITTED FOR PUBLICATION

Jan 1, 1987

By Stephen Young

The continuous monitoring of free cyanide levels is an important part of gold recovery operations. Accurate and up to the moment knowledge of the free cyanide concentration can result in substantial cost savings by allowing reduced concentra­tions with lower fluctuations, while maintaining or increasing gold recovery. Reduced free cyanide levels also result in lower detoxification costs at the mill discharge which translates into further savings while meeting environmental requirements. As can be seen from the upper curve in Figure 1 (which is based on in-service measurements), without accurate monitoring and control, cyanide concentration fluctuates during the produc­tion cycle, and is maintained at a high level to err on the side of caution. The lower curve illustrates the improved control permitted by the installation of a CY ANCOR, giving a more consistent concentration over the process cycle, and safely allowing use of a lower concentration.

Jan 1, 1995

By Eric Johnson

"IntroductionHistoricalCyanidation is a leaching process, in world-wide use, to extract gold (and silver) from ores and concentrates. The process has many inherent advantages on account of its adaptability:a. to any scale of operation;b. to a wide range of ore types and mineral associations;c. to a wide range of physical characteristics of the gold particle size, alloy (electrum) or mineral (telluride);d. to relatively simple plant controls and operating procedures;e. to simple marketing procedures and quick cash return.The basic idea for cyanidation was first described and patented by a German chemist, L. Elsner, in 1846. Some forty years later, J.S. McArthur, a metallurgical chemist and R.W. and W. Forrest, medical doctors, all of Glasgow, Scotland, came to realize the import of the discovery and accordingly, registered patents in Great Britain in 1887 and in the United States in 1889. The keystone of the McArthur-Forrest patent registration was the use of weak (0.05o/o) instead of strong (1.0%) solution.The years 1890-1910 saw much progress in equipment design and the advance from batch to continuous processing to increase efficiency and reduce operating costs.In later years, technological progress followed advances in materials of construction and control systems. Current innovations include large-scale equipment, high-capacity thickeners, belt type filters and Steller, candle-type filters for plants using zinc dust precipitation. As well, environmental protection is increasingly a major concern.The technology of gold adsorption from cyanide solution onto activated carbon has made rapid strides in recent years. This has followed the initial efforts of Potter, Salisbury, Zadra and their colleagues of the U.S. Bureau of Mines Research Station in Salt Lake City, Utah, and the field work of Homestake Mining Company personnel, in Lead, South Dakota."

Jan 1, 1989

By P. R. Taylor

The ability to treat refractory gold concentrates that contain appreciable amounts of sulfur and arsenic, in an economic and environmentally safe manner is important to the gold mining industry. Processing alternatives include: autoclave oxidation, bacterial oxidation and roasting. Roasting may be the cheapest of all the alternatives if inexpensive methods can be found to contain the arsenic and sulfur. The research program, being reported here, has been evaluating the ability to use hydrated lime in the roaster to capture both the arsenic and the sulfur. Lime roasting is not a new idea, it was proposed for copper ores by Bartlett in the early 1970's (Bartlett and Haung 1973) and for cobaltite concentrates by Taylor in the early 1980's (Taylor et al., 1981). In addition, ores have been roasted that contained limestone and it was shown that partial capture of the sulfur was possible. Lime -sulfur containment has been proposed for the coal fired electricity industry, as well.

Jan 1, 1992

By J. Châteauneuf, R. Dupéré, D. Mrabet

"In gold processing plants, it is common to start gold cyanidation in the grinding circuit by simple cyanide addition or as a result of recycling residual cyanide. In such cases, advantages such as a decrease in gold lockup and reduced leach time have been noticed. The prevailing conditions in grinding circuits such as intense mixing, particle breakage and friction or high temperature are quite different from those found in tanks and so is the resulting cyanidation behaviour. To gain a better understanding of the cyanidation behaviour in mills and of the pertinence of cyanide addition in grinding circuits, lab tests were conducted using an industrial ore from Canadian Malartic mine. In this study, the effects of different parameters on cyanidation in grinding circuits were examined; parameters such as such as temperature, dissolved oxygen, cyanide concentration and pH. The results showed that the kinetic benefits of high temperature in the mill can overcome the low dissolved oxygen concentration thus leading to an overall gold dissolution kinetics improvement for temperatures up to 50°C. However, gold leach in the studied grinding circuit at lab scale caused an increase in cyanide consumption with a higher generation of iron cyanide and SCN-. These results were confirmed by tests in the Canadian Malartic plant where the cyanide addition was moved from the SAG mill to the leaching tanks resulting in a 20% savings in cyanide consumption.IntroductionCyanidation in grinding circuits can benefit gold processing by decreasing gold lockup and by reducing leach time. However, other aspects regarding gold and cyanicide dissolution come into play in the conditions prevailing in grinding circuits. Indeed, high turbulence, high temperature, recycling load, friction and particle breakage make cyanidation behaviour in grinding circuits different from in-tank cyanidation (Marsden and House, 2006). In several cases, cyanide in grinding is limited to a very low level or completely avoided such as in circuits with gravimetric separation, for ores requiring oxidative pretreatment or for preg-robbing ores. In other cases, water management imposes a certain recycling of residual cyanide. This problem is generally addressed by a case-by-case approach. However, the chemistry of cyanidation in mill circuits is worth investigating in order to assess the advantages and disadvantages."

Jan 1, 2016

By J. A. King, D. A. Knight

"The Porgera orebody is located in mountainous terrain in Enga Province, Papua New Guinea. An underground mine has been developed which produces up to 2000 t/d of ore grading over 2 ozs Au/t. Some 79% of the gold in the ore is free, with the balance in a highly refractory form as sub-microscopic gold evenly disseminated within a pyrite matrix.This paper describes the metallurgical plant that uses flotation and cyanidation circuits to effectively recover the free gold in the ore feed, allowing for wide variation in the gold head grade. The refractory gold component in the ore is stored as leached pyrite flotation concentrate and this concentrate will be later treated by autoclaving techniques to recover the contained gold.The ProiectThe property is located in the Porgera Valley 600 Km North West of Port Moresby. The remote location is 2500 m above sea level. The mine area has 3600 mm of annual rainfall and a temperate climate with temperatures ranging from 10° c to 22° c throughout the year.Alluvial gold was reported in the Porgera area in 1938 and has been an important source of revenue for the area for many years. Intermittent exploration was carried out until the 1960 1 s when Placer (PNG) Pty. Ltd. with Mt. Isa Mines commenced an extensive exploration program. The property was brought to production in 1990 by the Porgera Joint Venture group consisting of Mount Isa Mines Ltd, Rennison Goldfield Consolidated Ltd. and Placer Dome Inc, each with a 30% ownership and the Government of Papua New Guinea with a 10% share. Placer Dome Inc. is the manager of the property with construction under the direction of the Placer Dome Technical Services group."

Jan 1, 1992

By D. A. Knight

The property is located in the Porgera Valley 600 Km North West of Port Moresby. The remote location is 2500 m above sea level. The mine area has 3,600 mm of annual rainfall and a temperate climate with temperatures ranging from 10" C to 22° C throughout the year. Alluvial gold was reported in the Porgera area in 1938 and has been an important source of revenue for the area for many years. Intermittent exploration was carried out until the 1960's when Placer (PNG) Pty. Ltd. with Mt. Isa Mines commenced an extensive exploration program. The property was brought to production in 1990 by the Porgera Joint Venture group consisting of Mount Isa Mines Ltd, Rennison Goldfield Consolidated Ltd. and Placer Dome Inc, each with a 30% ownership and the Government of Papua New Guinea with a 10% share. Placer Dome Inc. is the manager of the property with construction under the direction of the Placer Dome Technical Services group.

Jan 1, 1992

By Edmund Leaver

IT is generally recognized that the .addition of limited small amounts of various lead salts may aid the extracting power of the mill cyanide solution in the dissolution of silver from ores and in some cases may aid in the treatment of gold ores. Excess soluble lead compounds retard the dissolution of precious metals by the usual mill cyanide solution. Another phase of cyanidation is the use of the zinc-lead couple as an aid to better precipitation of gold and silver from solution containing a low percentage of cyanide. The chemistry of the use of lead salts in cyanidation has been dis-cussed by Clennell;1 the addition of lead salts in various cyanide mills is recorded by von Bernewitz;2 and the reasons for the use of lead salts in cyanidation have been explained by Clevenger.3 This paper deals with the adaptation of cyanidation to a different condition, in which the presence of lead minerals in a gold ore that is refractory to direct cyanidation complicates the treatment. If free gold is roasted in the presence of sulfur and lead salts, or if pyritic gold ores containing even a small percentage of lead minerals are roasted to free the gold from the pyrite, lead compounds coat the gold particles enough to make them almost insoluble in the usual mill cyanide solution contain-ing lime for protective alkalinity. Also, the lead compounds remaining in the calcine are slightly soluble in the mill solutions and such dissolved lead may retard the dissolution of the gold by the removal of oxygen or

Jan 1, 1933

By L. Rademan

The kinetic leaching behaviour of a low-grade surface gold ore and a high-grade reef ore were evaluated to determine the achievable gold recovery from these ores and particularly mixtures of these ores. The reef ore material has a head grade of 13.40 g/t with a relative standard deviation of 3%, and the unprocessed surface ore material a head grade of 0.43 g/t with a relative standard deviation of 15.6%. It is concluded that the kinetic leaching behaviour of these free milling gold ores during cyanidation, is not influenced by mixing of reef and surface ore material. No statistically significant relationship exists between the achievable recovery by direct cyanidation and the head grade of the material fed. No ideal ratio of surface ore to reef ore could be established. It is recommended that these materials should be processed simultaneously to minimize the costs, security risks, and losses incurred in transportation.

Jan 1, 2012

By Robert Linton

THE Sierra Consolidated Mines Co., organized in 1909, owns, together with other holdings, practically all of the productive mineral area in the Ocampo district. Lying within this area are 15 mines, large and small, that had previously been worked and appear to have yielded, since the discovery of the camp, about 100 years ago, bullion of a total value of over $50,000,000. The deepest mine, the Santa Juliana, had been worked to 1,100 ft. below the outcrop. The reopening of the mines involved, first, extensive and thorough development to open up the known ore-shoots at greater depth and explore the ledges for additional shoots, and, second, a revision of existing equipment and methods, so as to increase output and reduce cost of production. This paper will give some account of the metallurgical treatment and a description of the new mill to be built at El Salto.

Jan 2, 1914