Search Documents

By G. R. J. Cooper

In recent years attempts have been made to develop software packages for shallow seismic refraction data analysis. In most cases, mainframe computers were used which were generally non-interactive, did not support graphics and were unfriendly to operate. With these facts in mind, a user-friendly interactive processing package written in PASCAL has been developed for the IBM PC. The package allows the following operations to be performed. (1) data tying, equalisation of reciprocal and common shot times; (2) overburden velocity analysis; (3) refraction leg identification on time-distance plots; (4) elevation correction of refractor data; (5) forward and backward phantoming; refraction leg extrapolation; (6) 'bedrock' velocity analysis; (7) 'time-depth' plot computation; (8) depth calculation. Numbers (6) - (8) above involve Palmer's generalised reciprocal technique of refraction data interpretation. The program is extremely flexible and makes much use of interactive high resolution graphics and 'popup' onscreen menus. The velocity analysis sections have statistical routines built in to provide error estimation. The programs allow data interpretation to take place in the field with a portable microcomputer while the data are still being collected; this is obviously not possible with any cumbersome mainframe-based software. Hence it becomes possible to see the effects of varying the data collection parameters (such as geophone spacing) upon the resulting interpretation and so enable adjustments to be made where necessary. Hard copies of the data may be obtained at all stages of the interpretation process using a small (A3) plotter, or the graphics may be dumped to a dot- matrix printer if a suitable plotter is not available.

Jan 1, 1987

Mixed integer programming (MIP) has been used for optimizing production schedules of mines since the 1960s. The major problem in the long-term production scheduling for an entire orebody is that the number of integer variables needed to formulate an MIP model is too large to solve the formulation. This number may reach well over one hundred thousand. To overcome this difficulty, this paper presents two new algorithms to reduce the size of the problem. These algorithms assign an earliest and latest possible start date for each machine placement, eliminating the integer variables that correspond to machine placement before its early start date and after its late start date. A case study based on Kiruna Mine, the second largest underground mine in the world, is summarized in the paper. It shows substantial improvement in the solution time required using the new algorithms. This increased efficiency in the solution time of the MIP model allows it to be applied to Kiruna Mine, with the potential to increase substantially the net present value (NPV) of the project.

Jan 1, 2008

The Proceedings of the above Symposium have been edited and published by the Symposium Committee. The Symposium was sponsored by the Australian Coal Association, the Joint Coal Board, and the United Nations Economic Commission for Europe. The Symposium was very well attended, with presentations from fourteen countries, including all the major coal-producing countries of the world. The Proceedings are presented in two parts: the Symposium Part and the Workshop Part. The Symposium Part deals basically with the theoretical aspects of outbursts and high-gas emissions in mines, while the Workshop Part is more practically oriented and describes case studies, and the management systems, and drilling technologies used in underground mines.

Jan 1, 1996

"Investment in diamond exploration has been declining over the past decade, in spite of positive long-term industry fundamentals and a growing interest in diamonds as an investment category. The lack of new significant discoveries in recent years has eroded investor confidence, yet no new discoveries are possible without investment in exploration. Junior ‘mine finders’ have been the hardest hit. Their agility, tenacity, and appetite for risk are not sufficient to attract the funding required, even at the greenfield stage. Developing new discoveries into mineral resources can be crippling without solid financial support. Junior incubators could play a crucial role, especially at the project evaluation stage – but where are they? Alternatives to traditional funding mechanisms have become available, many still untested in the junior diamond exploration space. Valuable lessons can be drawn from the past and used to inform emerging new strategies. IntroductionDiamonds are the ultimate expression of love. Their ancient and timeless allure continues to influence consumer emotions and behaviours across continents, cultures and age groups. Analysts are predicting a sustained supplydemand shortfall in the years ahead which will trend diamond prices generally upwards. With positive long-term industry fundamentals, one cannot help but wonder why funding for diamond exploration and development projects is so scarce.Investment in exploration across commodities – including diamonds – has been declining for a number of years, reaching a historic eleven-year low early in 2017. The lack of major diamond discoveries in recent years has done little to strengthen the case for investing in diamond projects, yet no new discoveries can be made without investment in exploration.Global estimates of known carats in the ground stand currently at 2.5 billion carats, which equates to around 18 years of production at current levels of 140 million carats (mct) per annum. Sustainable replenishment of depleting diamond resources is possible only through the development of new discoveries. This is what junior explorers are best at – but they need investors to fund their evaluation activities from early in the project development continuum."

Feb 1, 2019

By X. J. Lyu, Q. Liu, M. J. Lian, X. Q. Cao, X. F. You, B. O. Erdenekhuyag, H. Y. Zang

The slag-tailings based artificial reef concrete (ARC) is made of CaO-CaSO4 activated granulated blast furnace slag (GBFS) as cementitious material and deslimed gold ore tailings as aggregate. In order to investigate the potential application of the material as ARC, the strength development, hydration characteristics and application performance were investigated under different preparation conditions. Results indicated that using seawater as the mixing water can effectively promote the hydration of slag and generate a large amount of hydration products such as ettringite, CSH gel, hydrotalcite and Friedel ’s salt in the early curing period and so render the material with good early compressive strength. Seawater curing can also accelerate the hydration reaction in the early stage of hydration. The hydration reaction of slag and the compressive strength of ARC can be effectively promoted by increasing the specific surface area of slag. The 28-day compressive strength of the slag-tailings based ARC prepared with 30-50% CaO-CaSO4 activated slag and 50-70% tailings can reach to 19.88-42.87 MPa. Also, the material has a low surface pH value, good resistance to chloride ion penetration, and sulfate corrosion. Keywords: Artificial reef concrete, granulated blast furnace slag, deslimed gold ore tailings, compressive strength, hydration characteristics

Jan 1, 2020

The 101 st Annual General Meeting of The South African Institute of Mining and Metallurgy was held in the Gold Room, Transvaal Automobile Club, 60 5th Street, Lower Houghton, Johannesburg on Wednesday, 12th August, 1998. Obituaries The President announced the death, during the year, of the following members: Honorary Life Fellows and Past Presidents H.E. Cross, D.G. Malan, P.W.J. van Rensburg Life Fellows J.B. Rolfes, W.C. Walmsley Fellows H.F. Boshoff, M.L.A. Fitzgerald, J. Humphriss Retired Fellows H.S. Botha, E.Collier, J.L. Curtis, A.H.H. Davison, D.I. Legge, B.D. McNeice, J.A. Northcott, D. de V. Oxford, S.S.K. Penney, P.C. Pirow, J. Pope, A.J. Rossouw, A.N. Shand, E.P. Smit, H.V. Solomon, S.G. Taussig

Jan 1, 1998

By X. H. Li, Q. Zhang, X. Fei

Bauxite residue known as red mud (RM) is a by-product produced in massive quantities during alumina production by the Bayer process with a utilisation rate of less than 5%. A large amount of RM accumulated and produced continuously has had a seriously adverse impact on the surrounding ecological environment. The application of RM in building materials is considered to be the most effective and thorough way to make RM harmless and recycle resources for the reason that adding RM to concrete as a mineral admixture could not only consume a lot of RM, but also save cement and other energy-consuming industrial products. In this paper, the adaptability to cement and aggregate of RM was studied. The results showed that the compressive strength and flexural strength of concrete using ordinary Portland cement, slag Portland cement or fly ash Portland cement as cementing material showed different trends with the increase of the amount of RM. The influence rules of RM on the compressive strength of Portland cement, slag Portland cement and fly ash Portland cement concrete were similar, whether for silicate aggregate or carbonate aggregate. RM has a negative correlation to the flexural strength of silicate aggregate-ordinary Portland cement concrete, but a positive correlation to silicate aggregate-slag Portland cement, silicate aggregate-fly ash Portland Cement. RM promoted the formation of calcium carbonate crystals and inhibited the formation of ettringite and calcium hydroxide crystals in the matrix while ordinary Portland cement, Portland cement and fly ash Portland cement were used as cementing materials. This study provided support for the use of RM in concrete, the reduction of solid waste storage, and the saving of high energy consumption cement as well. Keywords: Red mud, cement, aggregate, adaptability, mechanical properties, mineral composition

Jan 1, 2020

By D. F. Malan, P. M. Couto

We propose a layout design for the UG2 Reef where weak geological alteration layers are present. The collapse of the Everest platinum mine in South Africa indicated that these layers substantially weaken the pillars. The popular Hedley and Grant pillar strength formula cannot be used where these alteration layers are present. Underground investigations at Everest mine and numerical modelling of the layout were conducted using the TEXAN code and a limit equilibrium model. Simulations of a collapsed area and an intact area allowed for a preliminary calibration of the model. This was subsequently used to explore modified layouts for these ground conditions. An alternative is to compartmentalize the blocks of ore using barrier pillars. The numerical modelling predicted that the barrier pillars appear to remain stable even in the case of large-scale collapses, provided their width exceeds 25 m. Main access routes into the mine can be protected by a double row of pillars at least 15 m wide to provide a safe travelling way. As a cautionary note, these conclusions are based on the model calibration and this needs to be refined in future. Calibration of the limit equilibrium model remains a challenge owing to the large number of parameters involved.

May 3, 2023

By M. Rossouw

The paper sets out the strategic importance of South Africa?s mining and minerals sector to the national economy. It relates how inexorable and accelerating urbanization and industrialization in emerging markets, especially in China and India, will translate into sustained demand for the minerals that South and southern Africa have in abundance. It warns that while countries buying raw materials from South Africa use these inputs as the basis on which to build value-added, employment-creating industries, South Africa is failing to exploit the economic benefits inherent in its mineral wealth, exacerbating its shortage of skills.

Jan 1, 2011

By K. Moxham, A. Smit, R. Pickering

Since the early 1970s research has been ongoing to develop a cost-effective way of continuously mining the narrow reef, hard rock, typical of South African gold and platinum mines. In the late1980s it was shown that impact ripping was a practical solution for the deep gold mines. In March2001 Lonmin and Sandvik agreed to co-operate in an endeavour to design and manufacture a prototype narrow reef mining machine with the ultimate aim of producing such a machine on a commercial basis that would enable Lonmin to create a safer and more productive environment within its mines and for Sandvik to enhance its leading position as a supplier of a new generation hard rock cutting machine. This paper describes the developed technology, the current progress of the delivery of the required objectives and the optimum mining layout for the roll-out of the mining method.

Jan 1, 2006

By Ron Tluczek

[Power Point Presentation]

Jan 1, 2006

By T van Zyl

Some standards are being used by the corrosion industry on a daily basis. This talk will cover how a standard comes into existence, the different types of standards and the voluntary/ compulsory nature of different standards. The maintenance of standards is discussed This talk also looks at how standards should be referenced, what reference to the mark scheme can be made and which national and international standards might be of value in the corrosion industry.

Jan 1, 2006

By P. W. J. Delport, E. Du Toit

Investing in a mining venture can be risky and stakeholders need transparent, unbiased reports to understand the Mineral Resources and Mineral Reserves a mining company holds. Readability and textual choice can be used consciously to manipulate perceptions, or it can be done unconsciously. This exploratory study investigates the readability and textual choice of supplementary Mineral Resources and Mineral Reserves Reports of companies listed on the Johannesburg Stock Exchange. The results indicate that narrative manipulation occurs in these reports through word choices that make the reports difficult to read, as well as specific narrative selections. This reduces the informational value of the reports. The results of the study will be useful to various stakeholders, such as mining company management, investors, investment specialists, financial analysts, and even employees and the general community, who all use these reports to make important decisions. It is also useful for the preparers of the Mineral Resources and Mineral Reserves Reports, Competent Persons, and other technical specialists to be aware of readability and that certain textual choices can affect the interpretation of these reports. It is recommended that bodies such as the JSE and the SAMREC and SAMVAL Code committees consider adding a plain language requirement to regulations, guidelines, and codes to ensure transparent, unbiased, and objective reports.

Mar 1, 2021

The visit which took place on the 18th February, 1972 was a departure in that the places visited had no direct connection with the work in which members of the Institute are normally engaged. It was refreshing and stimulating to see important and involved operations normally outside ones own trend of life and to have experts to speak about technical, financial and matters of general interest concerning their work, not forgetting their troubles and problems and how they overcame them. Carlton Centre The members of the Institute were received by Mr D. Appleton, Public Relations Officer of the Carlton Centre Limited, who introduced Mr L. R. M. Fee of W. Rhodes Harrison, Architect in charge of the project; Mr W. C. E. Skilton of Murray and Roberts, the Engineer in charge of the construction of the complex and Mr A. Home the Senior Operating Engineer of Carlton Centre Limited. Each of these gentlemen addressed the members giving short rundowns on the project with special reference to their particular sphere of the undertaking. A variety of particularly interesting statistics relating to the planning construction and the ultimate operation and maintenance of the complex was given. Mining engineers present had an opportunity to compare the problems encountered by them associated with depth to problems encountered by the civil engineer in the construction of a building rising to such an enormous height. To some of the members a sense of similarity of the labour problems encountered must have been recognised. After tea the visitors were divided into groups, each under the guidance of an official, and then visited the highest floor accessible and thereafter the 19th floor where the internal arrangements for airconditioning, lighting, plumbing, power supply and communication arrangements were explained. Thereafter a visit to one of the seven basements which houses all machinery required to serve this enormous complex enabled the visitors to see the standby power arrangements as well as the refrigeration plant. The visit finished in time to proceed to the Crest Hotel in Hillbrow for lunch. To our hosts for the visit to the Carlton Complex a special vote of thanks is recorded. Strydom Tower In the afternoon the party proceeded to the Strydom Tower where Mr Knight from the Public Works Department who was the Engineer in charge of the construction of the tower gave details on the construction and the extraordinary methods which had to be adopted to achieve the desired objectives and to overcome known as well as unforeseen difficulties. The comparatively short time taken to complete the project and the good safety record appeared to impress the visitors. The final phase of the visit was taken care of by Mr Bothma of Telecommunications Department of the Post Office, who gave an extremely interesting explanation of the telecommunication organization of the Post Office with particular reference to the part the Hillbrow Tower plays in the South African telecommunication system. Both gentlemen answered many questions willingly and interestingly. Following the explanatory talks the visitors were shown the technical equipment housed in the two top levels of the tower. Short explanatory talks gave members an insight into the workings of one of the most important aspects of modern life. Even to the amateur photographer opportunities existed to view and photograph the city from the highest available observation point. We are indebted to Mr Gouws, the Regional Director of the Post Office for granting permission to visit sections of the tower normally not accessible to the general public and to our hosts for the manner in which we were received and entertained on the explanation of the many interesting features of this important installation. In conclusion, the programme for the day can be classified as interesting, of exceptional educational value, and an opportunity to see something of the engineering skills put into two vast and ambitious undertakings and the results achieved.

By John W. Harbaugh, Alfredo Prelate

The goal of the study described here is to develop objective. quantitative methods for estimating the outcome probabilities of exploratory oil wells. The study employs the 're-experience' approach, in which historical data are used in a manner which attempts to recreate the past. Our past experience, of course, is the principal guide to the future. To appraise present-day oil prospects, however, we must analyze prospects that have been drilled in terms of how these former prospects were interpreted before they were drilled. An analysis of how they are interpreted after they were drilled is an inadequate guide to the future because our hindsight knowledge is superior to our foresight knowledge. Objective calculation of future outcome probabilities, then, requires that we attempt to treat past information in a manner analogous to that in which we must treat present information in forecasting future outcomes.

Jan 1, 2014

On 8th August, 1973, 57 members of the Institute visited Prieska Copper Mine at Copperton in the North Western Cape. After tea, the group was welcomed by the Management of the Mine, and Mr Grobler, the General Manager, gave an introductory talk. After they had been taken on a bus tour of the property, the members split up into groups and proceeded underground or to the concentrator. Of special interest to the mining members were the rock-handling methods in use at the mine. The stoping method that has been adopted is the continuous, long-hole sub-level open stoping system. The broken ore is moved with rubbertyred front-end loaders from the stope drawpoints to the ore passes. On the main tramming levels, the ore is collected by electric locomotives and discharged into the main shaft system at the bottom. At the shaft ore-pass system, a gyratory crusher that can accept rocks up to 1 m in diameter has been installed. The crushed product (minus 150 mm in diameter) will then be hoisted by a Koepe winder, which has a rated capacity of 900 tons per hour. The mine is also served by a declined roadway from surface, which facilitates the movement of heavy equipment. The most striking aspect is the productivity that can be achieved by the use of a trackless-mining system. For the production of 230 000 tons per month, it is estimated that 6 stopers and 7 developers will be required. The total labour force will be approximately 2500-2000 Bantu, 200 Coloured, and 300 Europeans. Training of maintenance and operating personnel is of the utmost importance, and it was interesting to note the extent to which non-White labour is being used in these occupations. Lunch was served at the single quarters, after which the group proceeded to the airfield for the return trip to Johannesburg. On behalf of the visitors, Professor de V. Lambrechts thanked Mr Grobler and his staff for the most interesting morning and for their hospitality,

Jan 10, 1973

By H. S. Sichel

"The valuation of diamond ferous deposits depends on (i) the density distribution, (ii) the size distribution of stones and (iii) the selling price structure prevailing at a particular time.In the density distribution the stochastic variable is defined as the Dumber of individual stones found per sample unit irrespective of the stone size. The density distribution is discrete and allows for barren sample units.As diamonds often occur in clusters, a Poisson mixture distribution is derived which is entirely new, as existing discrete distributions cannot represent the stone number frequencies found in nature.For the sizes of diamonds, which are measured by weight, a new compound logarithmic normal distribution is developed.Combination of (i), (H) and (iii) leads to a meaningful appraisal of diamond ferous ground expressed in monetary value per production unit of mining.Finally, confidence limits are calculated which allow for inference from sampling to recovery."

Jan 1, 2014

On behalf of the Council and staff of The South African Institute of Mining and Metallurgy, it is my privilege to wish all members and subscribers a very Happy Christmas and a Prosperous New Year.

Jan 1, 1988

By Willem Le Roux

The common law requires an employer to take reasonable steps for the safety of employees. In general, the duty of care means that the employer, acting personally or through its employees or agents, must take reasonable care for the safety of its employees (Van Deventer v Workmen?s Compensation Commissioner; 1962 (4) SA 28 T; Oosthuizen v Homegas (Pty) Ltd 1992 (3) SA 463 T).The duty of care includes the provision of safe premises, safe machinery and tools and a safe system of work. The obligation is not an absolute one, but is restricted by the concept of reasonableness. The common law duty may, in certain cases, include the assessment of hazards and risks. 2 International law Great emphasis has been placed in the Western world on the prevention of occupational diseases and injuries. Detailed statutes and regulations govern specific industries in many countries. See, e.g. the Control of Substances Hazardous to Health Regulations of the United Kingdom and various regulations applicable to the use of asbestos and lead, fire protection, mines and quarries, petroleum, etc. Risk management is an important part of managing health and safety. In the United Kingdom, the Management of Health and Safety at Work Regulations, 1999, require every employer to make a ?suitable and sufficient assessment of the risks to health and safety of his employees to which they are exposed whilst they are at work?. The particularity of the assessment is determined by the risk in question.

Jan 1, 2011

By A. Tosun

Muckpile fragmentation formed by blasting depends on the specific charge factor, the discontinuities in the rock mass, and the rock strength. Determination of the discontinuity characteristics and rock strength is a long and difficult process. These two parameters are directly associated with the rock drilling speed. Therefore, it is the drilling speed of the machine used for the blast-hole, rather than the blasthole discontinuity characteristics and rock strength parameters, that is used in the prediction of muckpile fragmentation before blasting. Primarily, it has been suggested that the muckpile fragmentation values can be correctly determined by establishing correlations between the efficiency of the loader and muck pile fragmentation, since fragmentation is directly correlated with the former parameter. Subsequently, a correlation predicting the drilling speed of the drill machine was developed according to the discontinuity characteristics of the blasting surface and the rock strength. Finally, a correlation was developed predicting muckpile fragmentation according to the specific charge factor and the drilling speed of the drill machine The data was obtained by conducting blasting tests in two different limestone quarries.

Nov 30, 2022