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By Segnit ER, Jensen G

The decoppering of soft and hard leads was investigated by stirring in an open pot, using sulfur or sulfur plus pyrites, or sulfur plus pyrrhotite, as reagents. Lead samples taken during the process were analysed for copper. Dross samples were examined by optical micro- scope, SEM and XRD. Soft lead containing silver can be decoppered satisfactorily by stirring with 0.1% S at low temperatures - close to 330¦C. Soft lead, whether containing silver or not, can be decoppered satisfactorily at higher temperatures by stirring with 0.1% S plus 0.4% pyrites. Then CuFeS2, Cu5FeS4 and PbS are formed, instead of Cu2S, CuS and PbS when using S alone. Hard lead containing tin can be decoppered satisfactorily by stirring with 0.1% S at temperatures from 320-400¦C. When stirring with 0.1% S plus 0.4% pyrites, reversion of copper from dross to lead on prolonged stirring does not occur. Hard lead without tin can be decoppered with S plus pyrites better than with S alone, but the presence of antimony hinders the decoppering, which is less effective on lead with 5.5% Sb than with 2.3% Sb.

Jan 1, 1980

Coal is of tremendous importance for the Czechoslovak econ- omy. The current annual primary energy demand being about 109 million tons of standard fuel (1 ton of standard fuel - 7,000 coal = 29,308 GJ), coal satisfies almost two thirds of our fuel consumption. If compared with the distribution of resources in the world's fuel and energy pattern, the situation in Czechos- lovakia is significantly different, as shown in Fig. I. One of the causes behind the difference is that the Czechoslo- vak oil and natural gas reserves and, hence, their production are insignificant, so that it is necessary to import them. Brown coal will continue to play an important role as a prin- cipal domestic source of primary energy even in the future. While the share of nuclear power is increasing, brown coal represents strategic reserves in the fuel and energy balance.

Jan 1, 1989

The æProfit Driver ModelÆ is a tool which builds costs from first principles and integrates revenue, costs and physical mining parameters and, hence, can quantify the impact and leverage on profit. In this paper an æexample mineÆ has been created to represent a typical Australian Open Cut Coal Mine. This has then been input into the Profit Driver Model to allow different variables to be tested. A series of variables were tested to determine which ones had the highest impact on profit and results are useful to management as a guide to the areas in which they can focus effort to achieve better profitability. Whilst the highest profit drivers are those external to the control of management and include selling price and exchange rate, the next most sensitive are those variables related to the geology of the mine and the mining method. These included coal quality, yield and strip ratio. Site management has some control of these. For example, the ability to vary the sequence of mining or improve the yield by a more efficient coal washing process. The efficiency of the workforce and management has similar impact to the mining variables. Finally, there are the supply variables, such as fuel, labour and explosives which are the least sensitive although, cumulatively, still significant. Each mine is different and the results of the example mine will not apply to all mines. However, the approach taken is universal and the tool illustrates a simple method to quantify the profit impact when changing variables. The benefit of the approach is the short time taken to get a set of results. This allows the more detailed and time consuming work to be more focused. The results illustrate that management has a significant influence on profitability.

Jan 1, 2000

Basicity(aO2−) has been known to affect the physicochemical properties of molten slags in the metallurgical processes. However, because of the impossibility of direct measurement of single-ion activity, various indirect measures such as capacity, redox equilibrium of transition metal ions, activity of basic oxides, and (theoretical) optical basicity have been proposed; but these basicity measures have been restricted within slag systems and the interaction between measuring elements and slag components has affected the quantitative estimation of slag basicity. Recently, since it was reported that solubility of noble metals in molten slags could be an indirect measure of basicity, the influence of slag basicity on the solubility of platinum and silver has been reported. The reaction mechanism of platinum dissolution into basic slags has been reported, whilst that in acidic slags has not (Nakamura and Sano, 1997; Sano and Nakamura, 1997; Nakamura et al, 1998). Richardson reported that the solubility of metals such as cupper, gold, silver, and lead in the CaO-SiO2-Al2O3 slag was presumably dependent on the atomic radius and the accommodation ability of the silicate network (Richardson, 1974). Swinbourne and You measured silver solubility in the Na2O-SiO2 slag over a wide range of oxygen partial pressure and suggested that silver would be present as both Ago and Ag0.5 in the slags (Swinbourne and You, 1999). For brevity, these previous works discussed the dissolution mechanism of silver into the slags based on the existence of silver as a neutral or molecular species. However, because the almost chemical reactions occurring in the slag are affected by the basicity, the reaction formula with O2- ion is required based on the ionic characteristics of the slag such as desulphurisation and dephosphorisation reactions as given in Equations 1 and 2, respectively.

Jan 1, 2000

By Ju Hao L, Jian L

A joint project between the Fan Kou Mine, the Guangzhou Research Institute of Non-ferrous Metals, the Julius Kruttschnitt Mineral Research Centre, and the Changsha Design and Research Institute of Non-ferrous Metals has implemented grinding control on a circuit consisting of two primary mills and a single secondary mill at the Fan Kou mine in northern Guangdong province, PR China. This paper describes the initial design of the control system and the changes made during its implementation. The initial design was to obtain maximum throughput at a constant product size. This was changed so that the control provided a constant product density at a set feed rate. The set feed rate is reduced when necessary to prevent overloading of critical components in the circuit. The reasons for the changes in the control strategy are discussed.

Jan 1, 1993

By Rozycki J

The results of shaft lining monitoring gave rise to an investigation of cracks observed in the structure. An hypothesis was made that the cracks might be due to stresses caused by energy wave propagation, triggered during blasting or by the rock falls. However, it could not be excluded that the cracks had their origin in the rheologic changes taking place in the concrete. To prove the hypothesis, an investigation of the scale of the increase of stress due to the energy triggered was undertaken. At the same time it was decided to attempt to determine the "damage threshold" for such material in the danger zone. In the paper the investigation and its results are presented, as conducted in one of the shafts. In conclusion, certain generaliza- tions are proposed to give a starting point in the consideration of similar problems elsewhere.

Jan 1, 1987

By Pirvics AI, Whitworth NR, Tuppurainen JMI

Process control applications to the unit operations in both the Lead and Copper Smelters are reviewed. The basic aim of this control is to smooth plant inputs to produce an output of consistent quality in terms of chemical composition, temperature and physical properties. Most effort has been put into the process bottlenecks, namely in the process baghouse of the Lead Smelter and in the Copper Smelter reverberatory furnaces. The method of approach is discussed, firstly extensive plant measurement and data logging plus identification of factors which most affect the unit operation and secondly control of these factors to smooth out variations. This has been possible due to the development in-house of on-line instruments to measure the critical variables and the external use of computers for plant control. Some of these instrument developments are also briefly discussed.

Jan 1, 1984

By Hughes A

Nchanga Division of ZCCM has installed and operated a trolley assist system on part of their truck fleet for some three years. This paper examines how the system came to be chosen and how the many features of construction and operation were dealt with. The economics and productivity of the system are presented as are the personnel aspects of acceptance and training. Zambia Consolidated Copper Mines is a state controlled copper mining company formed by the amalgamation of the former Nchanga Consolidated Copper Mines and Roan Copper Mines. The company operates seven copper mines the largest producer being the Nchanga division, which is scheduled to produce some forty-two percent of Zambia's copper production. The division operates four open pits and an underground mine which produce annually some 192 000 and 96 000 tonnes respectively of copper contained in ore.

Jan 1, 1986

Since its beginning, with the works of D. Krige and later, G. Matheron, geostatistics has been analyzing in detail the essential factors at play in ore reserves estimation problems, with the ever-present aim of an optimal use of the available information. Not only do the reserves depend on the geological in situ resources, they also require a correct appraisal of many technical and economical parameters. The objective of the present paper is to show how the method of technical parameterization of reserves, which is at the heart of the geostatistical approach, provides an extremely powerful and versatile tool for characterizing a mining project. After a review of the main properties of the technique, its use in the economic optimization of a project will be examined. Two examples from copper and gold deposits will be given.

Jan 1, 1987

By Mishra S. N, Mishra R, Sen P. K

Control of silicon in produced through the submerged-arc furnace can result in reduced power and coke consumption in addition to improving the quality of the hot metal. A thermo-chemical analysis of the production of ferro-chromium was carried out to devise strategies to control the recovery of silicon during the manufacture of ferro-chromium. The presence of three thermochemical zones in the furnace with respect to the reduction of silica was recognised from this analysis. Any strategy for the control of silicon recovery has to take cognizance of these thermochemical zones. The effect of various strategies on the silicon level in the hot metal have been evaluated. Possible strategies, such as the reduction of coke level in the charge; the replacement of quartz; pre-reduction of the ore and the control of the temperature profile are discussed in this paper.

Jan 1, 1999

By S Williams

The primary objective of most mining projects is to maximise the value delivered to the companyÆs shareholders. Achieving best practice performance and maintaining competitive advantage through low-cost production and high productivity is essential to achieving this aim. Benchmarking is an essential tool for the identification and implementation of best practice performance, and to realise continuous improvement by ensuring best practice becomes common practice. But to be successful, that is to deliver long-term value creation, benchmarking must be holistic and align operational performance with strategic intent. This paper outlines a rigorous and structured approach on how to conduct a successful benchmarking program that aligns operational performance with the businessÆs goals. Further it investigates the benefits that benchmarking can provide throughout the project life cycle and provides some key learnings from some of the worldÆs leading miners.

Jan 1, 2009

By Baynes F. J, Bermingham A. G

The 6000m long King Headrace Tunnel will be driven through hard Owen Conglomerate in the Eastern third and feldspar porphyry in the Western two thirds, with the anticipated hardness up to 350MPa unconfined compressive strength. Since the Commission had not driven a long, large diameter tunnel for some twenty years, major research was undertaken to assess the current tunnelling trends. Tunnel boring machines were compared with drill and fire equipment. Rail equipment was compared with rubber tyred equipment. Tenders were called with tenderers invited to submit alternatives if desired. Commissioning and production excavation using the equipment is discussed with the final conclusion being that the individual items of equipment purchased combined to make an efficient hard rock drill and blast system capable of progressing through all rock conditions likely to be encountered on the King and Anthony Schemes.

Jan 1, 1987

A large scale distributed process con-trol system has been successfully applied to the automatic control of aluminium reduction cells at Boyne Smelters. A three stage hierarchy of minicomputers and microcomputers is used to continuously monitor and control conditions in each cell and to manage the data generated during the process.The automation hardware was purchased on the basis of low cost, high reliability, prior use in the aluminium industry and a high level of backup under failure conditions. The hardware has met performance criteria to date.The process control strategies have continually been updated to minimise the energy and raw material consumptions in each cell. A major change to systems software has recently been made to decrease the development time for-future changes. Various low energy potline retrofit alterations are currently being investigated requiring significant changes to the process control strategies.

Jan 1, 1985

By Lewis J. W

The mineral sand orebodies of the east coast of Australia occupy approximately three per cent of the dune-heath-wetland coastal environment. They are associated with coastal plant communities ranging from Holocene high dunes carrying mature Eucalypt forests to low- lying heaths on Pleistocene deposits. Commonly, 0.25 to 1.5 per cent of the sand volume mined is removed from the site. Therefore, the volume change is insignificant. The equipment and techniques in use are flexible and the land can be returned in a manner suited to its subsequent use for grazing, subdivision or recreation. Landforms similar to the pre-existing are created in two case studies given. Sophisticated revegetation techniques are practised and are discussed in two case studies. Pre-mining vegetation surveys and post-mining monitoring are used to guide the management of the ecosystem.

Jan 1, 1976

By B Cope, N Hastings, D Webb

A Feasibility Study was completed in late 2002 to ascertain the risk and reward profile from the proposed deepening of operations at Perseverance Nickel Mine in Western Australia. The system and approach adopted to this brownfields extension work is outlined and the main components of the study are overviewed. In particular, emphasis is given to the integration of mine design and scheduling tools through to financial evaluation. Detailed comment is given on the ability of the system used to provide a robust project schedule complete with 3D animation. The level of importance in eliminating scheduling errors is demonstrated in relation to the reported bottom line viability of the project. It is suggested that this is an area where brownfields Feasibility Studies have lacked clarity and authenticity, leading to the creation of an unrealistic benchmark for project implementation.

Jan 1, 2003

By Anderson KG

Multi-seam mining under the western portion of Lake Macquarie NSW commenced in 1982. Up to three seams separated by partings ranging from 10 to 30 metres are mined simultaneously by Newcom Collieries. A feature of these workings is the minimal bedrock cover, which ranges from 130 metres down to only 40 metres. "Surface" subsidence control has an over-riding influence on the design of the workings. Subsidence considerations govern both the selection of the mining method and the dimensioning of the workings. To date, workings have been designed in accordance with the "Wardell Guidelines for Mining Under Tidal Waters". These guidelines are tabulated and evaluated in the light of advances in rock mechanics knowledge and local subsidence data collected since the Guidelines were formulated in 1974. The local and regional stability of shallow workings designed according to the Guidelines is evaluated.

Jan 1, 1986

By Nagai K, Moriyama K

Toyo smelter has been making s veral efforts to reduce and diversify energy for dealing successfully with such :n:;rgy problems as the first and second oil crises. ::,specially it is one of th:; most important subjects to substitute oil by alternative: energy source, because oil is expensive and unstable with respect to its supply. t _'hercfore i was decided to propel tnC ezhstitution of coal *jr oil. in the first place, the supple- mental fuel oil in the reaction shaft was replaced by oil to coal in 1981, and then th, fuel substitution of pulverized coal was achieved in the steam superheater in 1984. 3y these fuel substitutions about 7u,' of the total fuel energy at 2oyo smelter has been replaced by coal. in this paper the fuel substitu- tions at loyo smelter are described in detail.

Jan 1, 1987

The Shamrock Gold Mine has been brought from exploration to production within three years. Mining of the openpit is scheduled for June 1990 with commissioning in April of the 180 000 TPA carbon-in-pulp mill on old tailings and rock dumps. The development of a small openpit containing 344 000 tonnes at 3.6 g/t Au in a complex sulphide ore has required extensive metallurgical testwork to optimise recovery, and ensure profitability. The project has been undertaken in a changing economic climate, with increasing restrictive legislation. The decision to mine was further complicated by the escalating cost of installing a heap leach operation in South East Queensland. Decreasing costs of consumables, in particular sodium cyanide, and the opportunity to purchase a suitable transportable mill at a reasonable price made the project robustly viable as a CIP operation.

Jan 1, 1990

In-situ leaching of gold deposits has not become an option largely as a result the lack of suitability of cyanide as a lixiviant due to sluggish kinetics and high dependence on the availability of oxygen. A second problem area is the excessive cost of drilling the required number of injection and production wells needed to service a wellfield capable of maintaining any significant throughput or providing and acceptable level of gold production. Well spacing in in-situ leaching operations is limited by solution life, dissolution rate, and the need for solution control. With cyanide the life of an active solution capable of dissolving significant gold is severely limited by the availability of oxygen which cannot be readily replaced while the solution remains underground. The extremely slow gold dissolution rate also necessitates excessive contact periods in order to dissolve coarse gold.

Jan 1, 1991

By Daziel M, Corke P

Unit cycles in mining have not changed for many years. Productivity increases over the past three decades have mainly been achieved by using larger and heavier machines. This investment in size has probably reached the point of diminishing returns and increased productivity in the future will have to be generated by other means. One way of achieving this is through automation of selected unit operations, eg dragline overburden removal, truck haulage, ground support installation and secondary breakage. Although, in the past few years, there has been significant progress in this direction, we are still a long way away from even partial automation - especially in hard rock mines. This paper addresses the technical obstacles facing mining automation; suggests ways by which these obstacles may be overcome and identifies the role of industry groups and research providers in this process.

Jan 1, 1997