Search Documents

By M. Klapwijk

Ancient Metallurgy - In addition to the preceding three papers, the following three contributions were received for publication 1. An analysis of Bantu-made iron implements from the Letaba district M. KLAPWIJK INTRODUCTION It has often been stated that it is hardly possible in South Africa to classify Bantumade iron hoes according to their places of origin and manufacture. It is well known that these hoes were used for barter, and as currency in the purchase of livestock or the payment of lobolo, although reports of the value of the hoes differ widely. The difficulty in their classification has arisen from their distribution over a very wide area.

Jan 1, 1974

1. Book review Assay and analytical practice in the South African mining industry, byW.C. Lenahan and R. de L. Muray- Smith. Johannesburg, The South African Institute of Mining and Metalurgy, 1986. RlOO (R80 to Members). Reviewer: N.G. Randolph 2. Canadian publications A market profile for industrial minerals in Canadian manufacturing sectors, by M. Prud'homme and D. Francis. 1987. Micromedia Limited (144 Front Street, Toronto, M5J 1G2, Canada).The following three publications are available from the Centre for Resource Studies, Queen's University, Kingston, Ontario, Canada K7L 3N6. An analysis of Japanese coking coal procurement policies: The Canadian and Australian experience, by D.L. Anderson. Feb. 1987. $25. Technology policies in the Canadian mineral industry, edited by M.J. Wojciechowski. Sep. 1986. $20.Value-added taxation: Issues and impact for Canadian mines, by B.l. Dyack. Nov. 1986. $7.3. Mintek reports Report M295 A mineralogical investigation of refractory gold ores and their beneficiation, by P.M. Swash. Report M296 The determination, by distilation-spectrophotometry, of chlorine in apatite-type materials containing fluorine, by M. Solomons. Report M297 The interference of zirconium in atomic-emission spectroscopy using inductively coupled plasma, by P.l. Wright.

Jan 1, 1987

By A. J. Lynch, N. W. Johnson, D. J. McKee, G. C. Thorne

The behaviour of minerals in sulphide flotation processes, with reference to simulation and control. by A. J. LYNCH, Ph.D., N. W. JOHNSON, Ph.D., D. J. McKEE, Ph.D., and G. C. THORNE, B.Sc. (Hons.) (Visitors) In sulphide flotation processes, there are two mechanisms by which particles are transferred from the flotation pulp to the concentrate: adhesion to air bubbles and natural flotation, and entrainment in the froth. The entrainment mechanism is particularly important for particles of non-sulphide gangue, which do not absorb collector. The importance of controlling the recovery rate of water was illustrated in plant testwork in which selectivity between valuable sulphides and sulphide gangue, and between valuable sulphides and non-sulphide gangue, was altered by manipulation of variables affecting the water recovery rate. The two mechanisms should be recognized in the development of a control system. Most of the control schemes in operating plants have concentrated on reagent additions, which affect the natural flotation mechanism. Although control of the chemical environment is clearly of paramount importance in flotation, plant tests have shown that control of the variables affecting the entrainment mechanism is also important.

Jan 4, 1974

By D. Mark, S. R. Hunneyball

The ongoing revision of the Respirable Dust Regulations (RDR) by the UK coal mining industry includes the introduction of personal exposure monitoring for underground mines, rather than the fixed point sampling of workplaces. The initial choice CIP10 personal respirable sampler, failed during the underground trials because of the transfer of large non-respirable particles to the respirable dust deposit under vibration from man-riding belts, and of adverse effects of high winds and high dust loading on the flowrate through the sampler. These effects were validated in laboratory simulations of these conditions. A cyclone-based personal sampler is showing promise as an alternative.

Jan 1, 2003

By N. Thorp, S. J. Bluhm

It has long been recognized that the provision of an acceptable thermal environment minimizes the danger and the adverse effect of heat stress, which is directly linked to decreased productivity, increased accident rates, and excessive physiological strain in workmen. Refrigeration in one form or another helps to provide this acceptable thermal environment. This paper outlines the problems encountered in a working area, and the steps taken to alleviate environmental conditions in some stopes with the introduction of selective cooling employing small water-chilling units in conjunction with specially designed stope coolers. Performance figures are given for plant and stope coolers, and the effectiveness of the system is assessed from an evaluation of the improvement achieved in the environmental conditions.

Jan 1, 1986

By A. J. S. Spearingt

The hydraulic transportation of relatively dense slurries for backfill purposes is typically carried through vertical and horizontal pipelines under gravity. Wear in backfill pipelines has become such a major problem that it is now one of the main reasons for the relatively slow build-up of placed backfill in spite of encouraging performance results in the gold-mining industry. This paper describes tests on pipeline wear that were carried out on classified tailings from the backfill plant at Vaal Reefs East. The testwork was carried out under various conditions of slurry relative density, slurry velocity, and pipeline diameter. Empirical relationships are presented for each transportation and pipeline parameter evaluated and, finally, overall relationships between pipeline conditions and transportation parameters are proposed.

Jan 1, 1992

By R. I. Klintworth

The multi-reef area of Cooke 3 Shaft provides a unique mining challenge on account of the very thin middlings between the pay bands and the marginal values of the reef. It is uneconomic or impractical, because of the excessive heights, to mine the middlings using conventional stoping methods. The development of suitable mining methods is discussed with particular emphasis on the control of water inflow and the policy of not jeopardizing or sterilizing other reef horizons by the mining method implemented. No definite solution is currently available, but with the aid of instrumentation, computer analyses and mechanized mining equipment, the mine continues to attempt to maximize extraction and profits.

Jan 1, 1988

By M. Ndabeni, J. H. van Vreden, M. Le Roux, Q. P. Campbell

It is not uncommon for gold slurry ponds or screen oversize dumps to contain several different types of carbon-rich contaminants. These contaminants act as robbers of dissolved gold which has a detrimental effect during the downstream carbon-in-leach (CIL) or carbon-in-pulp (CIP) processes. With a renewed interest in the reprocessing of contaminated gold waste ponds and dumps, preconcentration of the feed to either the CIL or CIP process becomes important to maximise profits from these resources. An added advantage in removing these resources, which were once thought of as being uneconomical, is the availability of land that can further be rehabilitated for community development projects. For gravity separation, an example of suitable technology is the Reflux Classifier (RC), which can be used for the separation of materials of different densities and can be used as a pre-concentration step. In this project, a laboratory-scale Reflux Classifier was used to pre-concentrate a gold-bearing sample obtained from a waste dump situated to the east of Johannesburg, South Africa. The material had an average gold grade of 1.9 g/ton and a carbon content of 10%. This material was first fed to a semi-batch Reflux Classifier that was used to fractionate it into several different density intervals by varying the fluidisation water feed rate, followed by continuous runs at fixed water flow rates. The results showed that a cumulative gold recovery of 60%, carbon recovery of 85%, and mass pull of 41% was possible for a fluidisation water feed rate of 15 L/min, while a rate of 20 L/min resulted in a gold recovery, carbon recovery and mass pull of 83%, 92% and 79% respectively, which translated into a concentrate gold grade above the set target of 3 g/ton. Continuous operation at 20 L/min yielded an underflow stream with 84% gold recovery at a grade of 5.4 g/ton. Keywords: Reflux Classification, gold recovery

Jan 1, 2020

By G. R. Addie, A. S. Roudnev

The Hydraulic Institute has completed the task of developing a new ANSI/HI standard 12.1-12.6 (2005) for rotodynamic (centrifugal) slurry pumps covering nomenclature, definitions, applications, and operation. The standard provides examples of the different slurry pump types and contains an extensive section on pump and slurry definitions. The effect of slurry on pump performance is covered along with the pumping of froth. Reference is also made to ANSI/HI standard 9.6.7 (2004), which contains anew method for pump performance correction when handling viscous fluids. Classification of slurry services is established and then is used to determine limitations on velocities and total head per pump in order to obtain acceptable wear performance. The new service class, head per stage and other limits are directly related to capital and other cost considerations that will affect solids transport system economics. The writers review the contents of the new standard, highlight the main points, and discuss the reason for the slurry classification, corresponding limits and expected implications, particularly with respect to operating costs of the pumps in solids transport systems.

Jan 1, 2007

Mixtures of MnO and graphite were reacted under argon at temperatures ranging from 1200 to 1425°C, and the loss in mass of the mixture was recorded continuously. The results showed that the rate of reduction of MnO increased as the temperature increased and the ratio of MnO to C decreased. The effect of the particle size of MnO and of graphite on the rate of reduction at I350°C was very small in the range 63 to 250 µm for MnO and 45 to 355 µm for graphite. The rate of reduction at I350°C was increased markedly by the addition of Na2CO2 and K2CO3, was slightly increased by the addition of Fe2O3, was unaffected by the addition of CaO, MgO, and AI2O., and was decreased by the addition of SiO2. Some CO2 was always present in the effluent gas, and this was taken as evidence that the reduction of MnO occurred by way of CO2 as an intermediate product. The activation energy of the ratecontrolling step was 57,5 kcal, and this was similar to the measured activation energy for the gasification of graphite by CO., namely, 61,S kcal per mole of graphite. A simple kinetic model was derived on the assumption that the gasification of graphite was the ratecontrolling step, and the results over the temperature range 1200 to I425°C, when plotted in the appropriate form, yielded straight lines as predicted by the model.

Jan 1, 1980

By K. Kabezya

A study on slag dispersion in a model of bottom-blown bath smelting converter was undertaken at room temperature. The aim was to investigate the behaviour of the dispersed slag phase at various operating conditions with very high gas flow rates in low slag volume (10%) systems. For simulation purposes water, paraffin-oil, and air were used to represent the bulk steel, molten slag, and gases respectively in a one-fifth cold model of the commercial 100 t Creusot-Loire-Uddeholm (CLU) converter used in the manufacture of stainless steel in South Africa. Dimensional analysis was done to correlate mathematically the dispersed phase holdup with the operating conditions and the modified Froude number. The overall expression of the holdup revealed that the dispersed slag phase decreased with the vertical distance from the original interface between the liquid phases. The dispersed phase also decreased with the radial distance in the water plume zone toward the sidewall. The holdup was apparently much higher on the side of the reactor where there were no tuyeres. The modified Froude number ensured the correlation between the model and the prototype.

Jan 1, 2014

By T. Ono, B. Altansukh, S. Kawamura, K. Haga, A. Shibayama, Y. Takasaki

In recent years, the grade of silica in zinc concentrate has increased due to the degradation of zinc content and the increase in impurity content in natural ores. It implies that the development of silica removal technology from zinc concentrate is necessary to solve problems in the smelting process caused by the high content of silica in zinc concentrate. In this paper, the authors investigated the silica removal processes from silica-rich zinc concentrate by mineral processing approaches such as re-grinding and flotation. This study focused on the pulverisation process as a pretreatment for the investigation of individual minerals' liberation from the silica-rich zinc concentrates using different kinds of pulverisers. Flotation experiments were performed to separate silica and zinc concentrate from the pulverizsd feed sample using a pH regulator (NaOH), activator (CuSO4), collecting agent (PAX), and foaming agent (DOW froth 250). Results showed that the liberation rate of silica (SiO2) was reached 75% from 13% by pulverisation in an attritor with a 2 mm ball in diameter, while silica accumulated in a fraction over 20 mm in size. Flotation experiments indicated that silica removal efficiency was achieved by 44% from + 20 mm fraction obtained from pulverisation whereas the grade of silica in froth reached 1.85 mass% from 4.5 mass%. Results indicate that silica could selectively separate from silica-rich zinc concentrate, and 99.8 % zinc recovery is achieved under the studied conditions. Keywords: Zinc concentrate, silica, pulverisation, liberation, sieving, flotation

Jan 1, 2020

By A. de Souza

On Thursday, 6th February, 1992, D. Jan Visser, the Executive Director, NPI (National Productivity Institute), addressed the Productivity Breakfast of the SAIMM-Vaal Triangle Branch in Vanderbijlpark. The Breakfast was held at the Riverside Holiday Inn, and was attended by 50 senior and middle managers in organizations in and around the Vaal Triangle, as well as by Richard Beck, the President of the South African Institute of Mining and Metallurgy.

Jan 1, 1992

By O. G. Pauw

The relationships between mill power and pebble load, bulk density of the load, and circulating load were investigated on the pebble mills in the grinding circuit at Buffelsfontein Gold Mine. This paper describes the most significant relationships among the operating and control variables on the plant, and illustrates these by reference to experimental data gathered from the plant during operation. The results were used for the development of very successful multivariable peak-seeking controllers for the pebble load and bulk density of the load on these pebble mills. The peak-seeking control algorithms are described in detail. The control system has operated successfully at Buffelsfontein for more than 18 months and is still in operation.

Jan 1, 1985

By I. M. MacGregor

This paper discusses the possible use of petrological data and proximate analyses in the prediction of cutting forces for coal. It is restricted to the development of univariate predictors based on data from thirteen collieries in five major Transvaal and Orange Free State coalfields and three coal provinces. The aim of the work was the identification and development of the best predictors of mean peak cutting force and Hardgrove grindability index from among the independent variables evaluated. The data, which were obtained by use of the penetrometer developed by the Chamber of Mines Research Organization, were processed according to the SPSS computer package. The analysis revealed reasonable correlations between the Hardgrove grindability index and (1) the volatiles and vitrinite content in the Vereeniging-Sasolburg and South Rand Coalfields, (2) the contents of vitrinite, vitrinite plus exinite, and minerals plus inertinite in the Eastern Transvaal Coalfield.

Jan 1, 1985

DECEMBER, 1971 The Wanders Club, Johannesburg Sunday, 9th April, to Friday, 14th April, 1972 The Tenth Symposium which is the first ever held outside the North American continent is being organised by the South African Institute of Mining and Metallurgy (with the South African Council for Scientific and Industrial Research and the South African Council for Automation and Computation), in collaboration with the previous co-sponsors. '" The programme includes over 60 papers from thirteen different countries. Attendance promises to be good and interested parties who have not yet registered are earnestly requested to do so without delay. The closure date for registration application is 31st January, 1972. The objective of this symposium is to pool experience and knowledge and to discuss new and potential developments for the planning and control of mineral projects. The papers which are to be presented will indicate the progress which has been made in this direction through the successful application of operations research, mathematical, statistical and computer methods. The intention is to bring together those persons responsible for managing various operations in the mineral industry with those engaged in the development of such mathematical and computer techniques as could assist this management. All interested parties are welcome. PRE-REGISTRATION (please return enclosed form as soon as possible). Applications for registration close on January 31, 1972. The fee payable on application will be R70. Late applications may, subject to vacancies being available,

By А. Klemyatov, T. Vologdina, U. Gordeeva, S. Zbinets, А. Kalugin, N. Rozhdestvenskiy

The plants integrated in the PhosAgro group of companies perform processes from scientific research to the project, from ore mining to shipment of fertilisers and feed additives to consumers. An extensive process chain maintains smooth interaction at all stages from research to production. As an example, the paper shows the revamp of two beneficiation plants (ANOF-2 and ANOF-3), requiring a comprehensive approach to task solving. The intention of the revamp was to increase the total yield of apatite and nepheline concentrate, taking into account the gradual decline in the quality of ore being processed and ensuring the yield stability of final products during re-equipment of the plants. At ANOF-3, the crushing and grinding cycle was modernised, the production of nepheline concentrate was implemented, and the capacity of apatite flotation, dehydration, and drying was increased. At ANOF-2 a new process chain was implemented for the production of apatite concentrate in workshops previously used for the production of nepheline concentrate. The main building was withdrawn from operation, where ore grinding, apatite flotation and apatite concentrate thickening had been carried out. The total increase in apatite concentrate yield at two beneficiation plants was 1.3 times. A further increase in concentrate production is planned. Keywords: Apatite, nepheline, fertilisers, beneficiation, flotation, column flotation machines, revamp, fine screening

Jan 1, 2020

By P. Sebola, S. Rasmeni, K. Seripe, D. Chetty

"South Africa’s Northern Cape Province hosts semi-precious and gemstone occurrences that are sporadically mined on a small scale by local communities. Tiger’s eye, a gemstone known for its chatoyancy properties, is found in important deposits located near the town of Prieska, where is it intermittently mined. Challenges faced by small-scale and informal mining include mining without proper permits, risky mining practice in dangerous terrain, and illegal export of raw material without concerted effort at domestic beneficiation. As part of a study aimed at job creation and social upliftment in the region, tiger’s eye deposits in the Prieska area were assessed to assist small-scale miners to understand tiger’s eye grades and their distribution. This will allow not only more efficient and safer mining of these deposits, but also beneficiation of the raw product into tumbled stones, cabochons, jewellery, and other small artefacts for sale. A hub established in Prieska by Mintek trains locals in the beneficiation of tiger’s eye. Supply to the hub must make use of a consistent grading system, which is discussed in this paper. Together with proper mine licensing, such an approach will develop mining and beneficiation skills, and create and sustain employment for the local community. IntroductionTiger’s eye is a semi-precious stone known for its chatoyancy property, which is caused by parallel, silicified asbestos fibres that impart a silky lustre to specimens. Deposits of tiger’s eye in the surrounds of the town of Prieska, Northern Cape Province, formed the focus of a study aimed at small-scale mining and beneficiation of this commodity. The Prieska tiger’s eye deposits are located along the N10 route to Upington (Figure 1). Tiger’s eye is unevenly distributed and occurs as lenses of various sizes, interbedded in gently folded metasedimentary rocks of mostly banded iron formation (BIF). The tiger’s eye occurrence in the Northern Cape Province, especially in the Prieska area, has not been extensively researched. There is thus limited information available in the public domain. The lack of knowledge on tiger’s eye distribution has resulted in local small-scale miners adopting a trial-and-error method of mining. Basic geological mapping and field evaluation of the deposit, coupled with professional judgement, are important aspects of any small-scale mining operation and can contribute significantly to the formulation of various acceptable and equally viable mining methods and practices."

Jan 1, 2016

By Z-B. Cheng, X-J. Liu

"Intensive mining of shallow coal seams tends to result in severe subsidence of the ground surface. Surface subsidence is a complex dynamic spatiotemporal process that constantly changes as mining advances. With Liangshuijing coal mine as a case study, 3DEC numerical software was used to simulate the development of the moving subsidence field from open-off cut to full subsidence on the working face. The results demonstrate that the formation of a subsidence field is directly related to the coal seam depth H and the extent of the mine workings. Taking the advance distance of the working face as the unit of scale, the process of surface subsidence can be divided into four stages: micro-change (H/ p), the development of surface subsidence (2H/ p), the formation of a movement subsidence field (3H/ p), and dynamic balance (4H/ p). The changing movement of a subsidence field can be fully described by the characteristics of surface subsidence value, curve slope, and the inflection position. The results provide important technical support for predicting surface subsidence and the temporal–spatial evolution features of mining subsidence. IntroductionChina’s coal output was about 3.52 Gt in 2017 (China National Coal Association, 2018), making it the largest coal producer in the world, accounting for almost half of total world coal production. Coal production and distribution play a vital role in the energy industry of China. However, entire overlying strata, from coal seam to surface, are disturbed as a result of long-term, high-intensity and large-scale mining, causing surface subsidence. This results in groundwater loss, surface desertification, vegetation loss, and mud-rock flows. These issues have become topics of common concern throughout society. According to related research results (Liu 2008), the area of surface subsidence caused by coal mining in China has reached about 600 000 ha, some 0.2 ha (and up to 0.42 ha) of surface subsidence for every 10 000 t of coal produced. Surface subsidence disasters not only damage buildings, water conservancy, transportation infrastructure, and farmland, but also cause adverse effects on individual and community lifestyles, environmental hygiene, and economic development. Deterioration of the ecological environment in mining areas has a long history and is very harmful (Lu, 2015)."

Feb 1, 2019

By HORNICKA OSTRAVA

The Czechoslovak Scientific-Technical Institute has arranged the international conference 'Hornicka Ostrava' for four or five days at the end of October, 1969, as part of the preparation for the international 'Miners' Congress' on deep coalextraction in 1970. The keynote of the conference is 'New Techniques in coal mining,' and will be covered by five groups dealing mainly with: 1. New trends in the opening of mines, optimal parameters, projections, equipment, utilization of computers for economic analyses, etc. 2. Increase in efficiency of coal extraction in deep mines, technology, concentration, pressure control, optimization of material and coal transport. 3. Modernization of devices for increased safety and working conditions, new trends in explosives, new techniques for reducing environmental diseases. 4. Innovations in deep level coal extraction, mechanization, rationalization, automation, etc. 5. Other topics about modern techniques in mining. Address your enquiries to: Ing. Karel Kalas (Secretary of the Conference), Dum Techniky Cs YTS, Ostrava 1, Jesenkiho 7-9, Czechoslovakia.