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By E. Shekarchi

A year after the Soviet Union invaded Afghanistan and replaced President Amin with their choice, President Karmal, Afghanistan remained in turmoil. In some respects, the political and economic situation in Afghanistan was no better by the end of 1980 than it was preceding the December 1979 invasion. The Government faced widespread and growing alienation and resistance, virulent factionalism within the ruling party, and an acute shortage of material. The mining sector of the country did not fare better either; the only raw material produced in a significant amount was natural gas, which was exported mainly to the Soviet Union. No statistics on production of other minerals and materials were available by yearend. Most of Afghanistan's gas production was from the Hodja-Gugerdag Field, southeast of Shibarghan. The gas flow from this field had been about 300 million cubic feet per day since 1961. An estimated 230 to 250 million cubic feet per day of Hodja-Gugerdag's production was moved by pipeline across the Amu-Darya River into the Soviet Union. Most of the remainder was transmitted eastward to a 105,000-ton-per-year fertilizer plant and an electric power station built near Mazar-i-Sharif with Soviet assistance. After the Soviet invasion, the second gasfield, Djar-Kuduk, in the Shibarghan area, was brought under production. This field, which will produce about 200 million cubic feet per day, consists of four gas zones in the Jurassic and lower Cretaceous zones between 3,000 and 8.500 feet deep. The gas has a high hydrogen sulfide content, with considerable carbon dioxide, A new treatment plant was built at Djar-Kuduk by Soviet technicians under a turnkey contract at the end of 1980. It is believed that most of the Djar-Kuduk's initial flow will be sent to the Soviet Union.

Jan 1, 1982

By McLennan T, Howells E, Zastawny H, Watt J. S

Nuclear techniques have been used to determine the solids weight fraction (W) and ash content of (fine) coal in slurries independent of voidage variations. The method is based on the correlation between W and the hydrogen concentration Hsl (wt/wt) of the slurry. Hsl is determined by combining measurements of neutron moderation and ?-ray transmission. Both Wand ash content are determined by combining the above measurements with the ash-sensitive measurement of X-ray backscatter compensated by a measurement of iron K X-ray intensity.The nuclear analysis system, called the SIRO coal slurry gauge, has been proved in a six-week plant trial at the BHP Steelworks washery at Newcastle, NSW. Several probes, each containing a radioisotope source and scintillation detector, were immersed directly into the coal slurry in the feed box upstream from the bank of flotation cells. For 140 samples W, ash and voidage varied in the ranges of 0 to 13 wt percent, 26 to 41 wt per cent and 0 to 4 vol. per cent, respectively. The r.m.s. difference in solids weight fraction, determined by probe measurements and conventional assay, was 0·52 wt per cent. Ash was determined with an r.m.s. difference of 2·0 wt percent in the coal. Better sampling techniques were used in the last half of the plant trial, and r.m.s. differences were 0.35 wt per cent solids and 1·5 wt per cent ash.

Jan 1, 1986

By P. I. Page

In mineral exploration the place that yields the first significant result is marked and two questions are posed immediately. Where should the next sample be drawn and how big should it be? At present the answers are arbitrary and ad hoc. They depend on personal experience and sentiment?that is hunch. The thought processes involved in reaching the decisions are unsatisfactory and unsatisfying for professionals. This paper proposes guidance on choosing sample spacing and sample size. The guidance is obtained from the grades of the samples. The grades also imply the extent of influence of each sample assay. Thus sampling and assay are integrated. The integration is achieved by changing the unit of value in which assays and grades are expressed and by exposing meanings and functions of grade beyond that of measuring rock value. The proposals are extended to guide comminution of particle size in sample size reduction and to deal with the problem of erratic high assays. Also, elucidation becomes possible of the computation of a reliable figure for average grade as a statistical weighted mean.

Jan 1, 2005

By R. Altindag

In rock cutting mechanics, the effects of the rock and coal brittleness on the efficiency of cutting bits are examined by many researchers. There is no universally accepted brittleness concept as a measure of cutting efficiency. The effect of the brittleness on rock cutting has not been completely explained. The aim of this study is to correlate the relationships between Specific Energy (SE) and brittleness concepts. The applicability of various brittleness measurement methods for rock cutting efficiency has been investigated. In this study, the raw data derived from previous experimental studies were used, and the relationships between SE and brittleness concepts were investigated. The two previously used brittleness concepts, which are named as B1 (the ratio of compressive strength to tensile strength) and B2 (the ratio of compressive strength minus tensile strength to compressive strength plus tensile strength), and a new introduced brittleness concept named B3 (the area under line in relation to compressive strength and tensile strength) were evaluated in this study. The relations among these brittleness concepts for rock cutting efficiency were established using regression analysis. There is no correlation found between the SE values and the brittleness of B1and B2values. But, the SE is strongly correlated with the brittleness of B3. It was seen that the suggested brittleness of B3concept could be used as an indicator in rock cutting efficiency analysis.

Jan 1, 2003

In the late 1970's and early 1980's a considerable number of large scale open pit mines were developed in N.S.W. and Queensland. At the time these mines were planned, the industry was characterised by rising coal prices, rising fuel prices, and a host of other labour and government constraints different to the situation today. Yet some mines have clearly been able to cope with this change much better than others. While one mine may now be expanding and profitable, its neighbour may still be labouring under painful adjustment processes. This paper examines the major reasons for this difference. It suggests more robust criteria for assessment of future projects to reduce their sensitivity to changes outside management control.

Jan 1, 1990

By Robert S. Shank

Introduction The Pinto Valley open-pit copper mine is located in southern Arizona, 11 km (7 miles) west of Miami. Production at Pinto Valley began in 1974. About 350 Mt (386 million st) of ore and waste was removed by the end of June 1982. At that time, the mine was using more than 90 major equipment items with a total mobile fleet numbering 320. Some of the major equipment consisted of four Marion M4 rotary drills; six P&H 15, 11.5- and 19.1-m3 (15- and 25-cu yd) shovels; and 24,136- and 154-t (150¬and 170-st) Wabco haulage trucks. This equipment was used to move more than 139 kt/d (154,000 stpd) of ore and waste. The mill was processing more than 50 kt/d (55,000 stpd) of mine ore. Shutdown A two-week vacation shutdown began in July 1982. Maintenance jobs were scheduled, and most employees left for the vacation. During the vacation period, copper prices fell below $1.32/kg ($0.60 per lb). Inventories remained at alarmingly high levels. At this point the mine was losing more money operating than it would by being shut down. The vacation shutdown was first extended to five weeks. But, after further evaluation, the mine was shut down indefinitely. In Dec. 1982, Cities Services Co., owner of Miami Operations (which included the Pinto Valley mine and mill), was acquired by the Occidental Petroleum Corp. On March 1, 1983, Occidental sold the operations to Newmont Mining Corp., and Newmont created Pinto Valley Copper Corp., as a wholly owned subsidiary. Copper continued to be produced by the Pinto Valley solvent extraction-electrowinning (SX- EW) plant because of its low cost per pound of production. To ensure proper equipment care during the shutdown, maintenance management was given three goals; • maintain the SX-EW plant; • maintain the environmental and pollution control systems such as domestic water pumps and mine dewatering; and

Jan 4, 1985

By A. M. Elmahdy

An amphoteric collector was tested for dolomite removal from phosphate ore. The effects of some operating parameters and their significance on the flotation of dolomite were studied using statistically designed experiments. The parameters studied were impeller speed, pH and collector dosage. Analysis of the results showed that pH is the most significant parameter. Moreover, a concentrate containing 0.53% MgO and ~31.1% P2O5 with a recovery of ~ 90% can be achieved at optimum values of studied parameters, i.e., a pH of 12, an impeller speed of 1,000 rpm and a collector dosage of 2.5 kg/t.

Jan 1, 2007

By J E. Nethery

At the Red Dome and Mungana deposits in north Queensland, Australia, it is proposed that mineralisation and alteration developed as a 'telescoped' overprinting continuum, ranging in style from hypothermal to epithermal, reflecting the major changes that developed in the regional setting over the period circa 325 - 290 Ma. Regional assessment suggests that this also applies to many other precious and base metal deposits within a 40 km length of the host Siluro-Devonian Chillagoe Formation.   A ten stage paragenetic sequence of structural preparation, multi phase intrusion and associated mineralisation, alteration and brecciation is postulated for the Chillagoe district.

Jan 1, 1995

Although auriferous beach and fore-dune sands at Five Mile Beach south of Okarito township had been intensively mined by hand and primative mechanical methods drilling of the sandspit by the Gold Development Corporation in 1929 indicated that the grade and quantity of undisturbed black and grey sand below the water table was sufficient to support a mining operation. Worked sand above the water table also contained fair prospects. The Okarito Five Mile Beach Gold Dredging Co Ltd, was formed and an hydraulically powered, bucket ladder, sluice box dredge built. In 13 years of operation (1931 - 1943) the dredge returned 556.39 kg (17 890 oz) of gold at a recovered grade of 225.4 mg/m3. A total of ú42 000 was distributed as dividends on the ú30 000 capital investment. Recent drill and bulk sampling at the northern end of the beach has confirmed that reworking of the historic tailings by a modern gravity recovery plant would not be economic.

Jan 1, 1993

By Jack Parker

Critical width Before we go further into pillar design, we should look into the matter of "critical width," because of its effect on pillar behavior. Critical width refers to the greatest width that the rocks above the mine can span before failure or, if there are pillars, the width to which we must mine before the pillars accept the full weight of the overlying materials. There are theories to help calculate that probable width, and they usually boil down to one-quarter or one-third of the depth of cover; but they don't always fit, and it would be better for us to understand the factors that control local conditions. Critical width may be controlled by the thickness or strength of one or more of the strata above the mining horizon. In a gold mine, we might have a thick granite or basalt above us, perhaps capable of bridging across most or even all of a small ore body. In that case, pillars might have to support nothing, or perhaps just the weaker or damaged rock below the strong main roof. Obviously it would be wrong to design for tributary load on pillars based on some lab-determined rock strength. In some coal mining districts in Utah, huge steps can be seen in the mountain sides, with slopes on weathered shales and vertical cliffs 100 or 200 ft high in thick, hard sandstones. The sandstones are capable of bridging across hundreds of feet, often making mining deceptively easy at first, but it becomes more difficult as greater areas are opened. Sometimes such a mining sequence leads to violent bumps and bursts as the wide spans of sandstone sag and bear down on the working faces, like giant nutcrackers, or as bridges eventually fail, releasing much pent-up energy.

Jan 1, 1993

By T. Banerjee, D. Felsher, G. Leavoy

"Lake Shore Gold is engaged in commercial gold production at both the Timmins West and Bell Creek mines, located in Timmins, Ontario. Run of mine ore is processed at the Bell Creek mill which consists of a conventional gold mill flow sheet involving crushing, grinding, gravity concentration and carbon-in-leach (CIL) for gold recovery. Since 2009, the operating capacity of the mill has been upgraded from 2000 tpd tonnes per day (tpd) to over 3,000 tpd. The most recent expansion involved the installation of a low aspect ratio SAG mill to replace the secondary crusher. Without operational data on the low aspect mill, combined with a site team that was new to SAG milling, there were many challenges in achieving the target throughput from the circuit. Through the implementation of AwaRE advanced controllers, running in closed loop with PRC fragmentation cameras as well as embedded PARC modules within the Allen Bradley PLC, the site was able to rapidly develop a best operating practise and has been successful in creating a stable and consistent operational environment. The process, lessons learned and eventual solution will be reviewed in this paper.INTRODUCTIONLake Shore Gold is engaged in commercial gold production at both the Timmins West and Bell Creek mines, located in Timmins, Ontario. Run of mine ore is processed at the Bell Creek mill which consists of a conventional gold mill flow sheet involving crushing, grinding, gravity concentration and carbon-in-leach (CIL) for gold recovery. Since 2009, the operating capacity of the mill has been upgraded from 2,000 tpd tonnes per day (tpd) to 3,150 tpd. The most recent expansion involved the installation of a low aspect ratio SAG mill to replace the secondary crusher. This endeavor was split into two phases: the expansion of the back-end (Phase 1) and the front-end (Phase 2) of the mill. Phase 1 of the expansion was completed at the end of 2012 and involved enhancements and capacity addition to the leaching and adsorption circuits, which increased the mill’s capacity to 2,500 tpd. Phase 2 of the expansion commenced at the end of July 2013 and involved the expansion of the crushing and grinding circuits. The expanded front-end of the mill now has a capacity of 5,500 tpd, and processes ore from both Bell Creek and Timmins West mines. The updated flow-sheet, as shown in Figure 1, illustrates the replacement of the two-stage crushing and ball milling circuit with a single stage crusher and a low aspect ratio SAG mill."

Jan 1, 2015

Recent and on-going studies on the leaching of gold, the properties and activity of carbon, developments in the elution of gold from carbon, and methods of recovering gold from solution are reviewed. Emphasis is placed on Australian contributions, and their impact on gold metallurgy. Consideration is given to the future development of selective solvent extractants, ion exchange resins or alternative reagents for cyanide.

Jan 1, 1987

By J Merrells

Fluor, together with our clients, has yielded significant reductions in the total cost of mining projects by employing a systematic and methodical process of cost reduction. This paper outlines this structured approach to reducing the total cost of projects through the gathering of information, the evaluation of the zero base design, and the development of the execution strategy for the project in the study phase.Over the recent iron ore boom the cost of growth projects escalated rapidly due to a variety of factors including the engineering cost of re-designing facilities, construction in remote areas and an increase in the ‘perceived’ capital requirements for maintainable and operable facilities.Fluor has made strategic steps towards safely reducing the capital intensity of projects, by working with clients to develop zero base designs which utilise the minimum technical requirements in order to meet the function of the plant and then add cost for safety, maintenance and operability only where clearly justified.This paper has set forth a structured three phased approach to focus the team on reducing capital cost while maintaining a low increase in engineering effort.The initial ‘gather’ phase focuses the team on acquiring information and identifying decisions that will need to be made so that the team can prioritise and focus the attention on areas that will provide the greatest benefit. Within this phase the identification of zero base design requirements, review of lessons learnt and analysis of capital cost levers, allows the team to identify the key decisions on the project that will affect the capital cost.In the subsequent ‘evaluation’ phase the team established the zero base design, using the hierarchy of cost reduction as a guide to focusing the team’s attention on high yielding cost saving opportunities.In the final phase the team develops the execution strategy which will yield the least cost using strategies and tools such as modularisation, standardisation, replication, strategic sourcing and 3D design.CITATION:Merrells, J, 2017. Reducing total project cost in the study phase using zero base design, in Proceedings Iron Ore 2017, pp 621–626 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By Manuel Pérez-Tello, María M. Salazar-Campoy, Óscar Rodríguez-Hoyos

A common problem during the operation of the Kaldo furnace is the formation of accretions and blockage of the injection lance due to splashing. This typically occurs during the processing of anodic slimes for the production of doré. In this work, a 1:7 scale model of the Kaldo furnace currently in operation at Metalúrgica de Cobre, Mexico, was built in transparent acrylic plastic. Water and colored oil were used to represent the doré and slag, respectively. The model was used to determine the maximum penetration distance of the injection lance under a variety of experimental conditions at room temperature. Input variables included two types of oil, rotation speed, inclination angle, and the fraction of the vessel volume occupied by the liquids (φ). A mathematical correlation for the dimensionless maximum penetration distance of the injection lance d ∗ as a function of φ, the Froude number of the liquids in the vessel (Fr), the Reynolds number of the gas jet (Re), and the oil-to-water kinematic viscosity ratio (η)was developed. Reasonable agreement between the calculated and experimental values was obtained. Digital images showed that splashing was caused by the turbulent gas jet impinging upon the free surface of the liquids, whereas the cascade effect was negligible. The results of this work have been useful to improve the operation of an industrial Kaldo reactor.

By Ramón Alanís, Filiberto Orrante, Andrea Festa, Baldomero Gutiérrez, Fernando Cornejo

"SGS implemented two rules-based fuzzy logic expert applications on two grinding circuits operated by Peñoles Group in Mexico. Both expert systems are based on control strategies that push against process constraints to improve throughput. Based on proven methodologies, the projects also required some new approaches that led to permanent changes to the mill control strategy.This paper provides descriptions of the implementation, operation and performance of both expert systems. It also reviews how improved production rates were achieved through the use of a common set of expert technology tools. An overview of the resulting control strategies implemented on the two circuits is presented. The paper also discusses the identification of the process constraints within each circuit and how these constraints are used within the expert systems.INTRODUCTIONMexico-based mining company Peñoles Group and the Advanced Systems group at SGS, formally known as MinnovEX Technologies Inc., collaborated on the implementation of two expert systems in two grinding plants, both located in Northern Mexico.The primary objective of the expert systems was to increase throughput whilst still maintaining the cyclone overflow product size within an acceptable range. The secondary objective was to achieve a high level of utilisation of the expert technology.In order to achieve these objectives, SGS proposed a proven methodology which leveraged the existing operating and technical expertise at site through the client’s involvement in the design and implementation stages. The in-house operating and technical expertise of SGS was also brought to the project and implemented with the client’s approval at all stages. At both sites the final acceptance was defined upon meeting both process and utilization parameters.The development and deployment of rules-based fuzzy logic applications has matured as a technology and consequently, clear definition of process states and their place in the logic structure to control a given circuit are now transferable. The key to the robustness of the control logic depends on selection and tuning rules for maintaining stability and optimizing a given circuit. Application integrators need to have a standardized approach for timely integration and deployment; a critical component to avoid the common critiques that expert applications are idiosyncratic and difficult to maintain."

Jan 1, 2009

By Forrest T. Moyer

INJURY experience and employment data are presented in this chapter for metal and nonmetal mines, stone quarries, sand and gravel pits, iron blast-furnace slag plants, and metallurgical plants (including ore-dressing and nonferrous reduction plants and refineries) in the United States. Employment and injury experience data for all mineral industries are given in volume II. The 1962 figures are preliminary summations which are subject to revision. They were compiled from all reports from producers received by the Bureau of Mines through April 15, 1963. The data for metal, nonmetal (except well and brine operations), stone, and sand and gravel operations were collected by a mandatory reporting system under the provisions of the act of September 26, 1961, Public Law 87-300 (75 Stat. 649). The act authorized the Secretary of the Interior to study the various aspects of safety in metal and nonmetal mines (excluding coal mines) and report the findings 2 years sub-sequent to the enactment of the law. Data on nonmetal well and brine plants and nonferrous reduction plants and refineries were reported voluntarily by the operators. METAL MINES Preliminary data for the metal mining industry comprise reports on 1,871 mines and pits. The combined fatal and nonfatal injury-frequency rate was 31.95 per million manhours in 1962, a decrease of 8 percent from the similar rate of 34.54 in 1961. Metal operations reported a total of 61 fatal and 3,201 nonfatal injuries.

Jan 1, 1963

Recent data contributions to New Zealand Mesozoic terrane geology confirm the consensus interpretation thatNew Zealand grew by the progressive addition of material by plutonic and accretionary processes along the Gondwana margin. The data also: 1. emphasise the discontinuous but inter-related nature of these processes of continental growth, 2. better establish a direct Gondwana correlation of the Western Province and probable Gondwana provenance of at least some of the Eastern Province, 3. suggest specific times and places when passive or strike-slip rather than subduction regimes are recorded along the south Gondwana margin, and 4. potentially lead to interpretations emphasising parautochthonous rather than far travelled relationships between many New Zealand terranes.  

Jan 1, 1995

By Freeman C, Dingley W

Addition of sodium nitrite-borax, sodium hydroxide, sodIUm carbonate, lime, or sodium silicate reduced wear of forged steel balls and cast iron slugs in wet grinding a complex zinc-lead-copper sulphide ore in laboratory ball mills. Maximum wear reductions were 27 per cent (forged steel balls) and 33 per cent (cast iron slugs) with sodium hydroxide and nitrite-borax additives respectively.Potential measurements of balls and slugs during grinding, and analysis of the data in terms of corrosion theory demonstrated that corrosive wear had been reduced or prevented by these additives. Actual per cent wear reductions were not equated to the rate of corrosive wear because of the undefined interdependence between abrasion and corrosion in wear processes. The investigation verifies that in laboratory ball mills corrosion is significant in the wear of grinding media and wear can be reduced by corrosion inhibition and pH adjustment.

Jan 1, 1978

By Carl Henrich

I have read with particular interest that portion of the discussion by Anton Eilers referring to the high-lime (and also high-alumina) slags made by August Raht in 1881, while smelting the Horn Silver ores at Franklin, Utah. The two analyses of such slags, furnished by Mr. Raht to Mr. Eilers are: (a) Not determined in this analysis. (b) Not given in Mr. Eilers' paper. Oxygen ratio, A1 as base. I. 0 in acid: O in base:: 18.1:18.9:: 0.96:1 11. 0 in acid :O in base:: 18.7:17.5::1.06:1 Average: 18.4:18.15=1.01:l Oxygen ratio, AI as acid. I. O in acid: O in base: :23.2:13.8:: 1.68:1 11. O in acid: O in base::23.1:13.5:: 1.76:1 Average: 23.15:13.4 = 1.73:l By assigning to alumina the the of a base, Mr. Eilers deduces the formula 3Feo.-2SiOa + 4Cao.2SiO². The nearest approach to a simple formula expressing the average composition of these slags, which I can figure, is 9RO.Al2O3.6SiO2. Allowing a ratio of 4Feo : 5Cao, we have for this formula:

Jan 1, 1917

By Manuel Pérez-Tello, María M. Salazar-Campoy, Óscar Rodríguez-Hoyos

A common problem during the operation of the Kaldo furnace is the formation of accretions and blockage of the injection lance due to splashing. This typically occurs during the processing of anodic slimes for the production of doré. In this work, a 1:7 scale model of the Kaldo furnace currently in operation at Metalúrgica de Cobre, Mexico, was built in transparent acrylic plastic. Water and colored oil were used to represent the doré and slag, respectively. The model was used to determine the maximum penetration distance of the injection lance under a variety of experimental conditions at room temperature. Input variables included two types of oil, rotation speed, inclination angle, and the fraction of the vessel volume occupied by the liquids (φ). A mathematical correlation for the dimensionless maximum penetration distance of the injection lance d ∗ as a function of φ, the Froude number of the liquids in the vessel (Fr), the Reynolds number of the gas jet (Re), and the oil-to-water kinematic viscosity ratio (η)was developed. Reasonable agreement between the calculated and experimental values was obtained. Digital images showed that splashing was caused by the turbulent gas jet impinging upon the free surface of the liquids, whereas the cascade effect was negligible. The results of this work have been useful to improve the operation of an industrial Kaldo reactor.