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By Whiten W. J

Data from ball mills of a wide range of sizes are analysed using detailed mathematical models and non-linear least squares fitting techniques. In this way model parameters are obtained describing the behaviour of ball mills over a wide range of mill sizes and operating conditions. These parameters define the flow and breakage of each size fraction of ore in the mill. Flow of coarse particles through the mill is found to depend on the proportion of coarse particles present. The breakage rates of coarse particles are found to decrease markedly with mill diameter for mills over 3 m in diameter.Simulation of grinding circuit throughput at constant productsizing for different mill diameters shows that throughput is proportional to theoretical mill power consumption for mills up to about 3 m in diameter. Thereafter the throughput gradually falls below that indicated by power consumption, the decrease becoming quite significant for large diameter mills. Simple qualitative physical arguments are presented to explain this behaviour. The models developed have applications to ball mill scale up. Work on their further development is continuing.

Jan 1, 1982

By Jifan X, Yongyu W, Liangjing L

Shallow interception of groundwater is a special dewa- tering form in the specific geological and hydrogeological conditions. It has an economic and technical effect. The roof of the Fankou Lead-zinc deposit is the Hutianqun aquifer made up of the limestone of the upper Carboniferous system. - A "water-bearing basin" is surrounded by the aquifuge and the aquitard below ¦0 m level at the Shiling Hill section in the Hutianqun aquifer. Based on the natural conditions, an interception gallery is excavated at -40 m level out of "the water- bearing basin", the other gallery excavated at ¦0 m level in the poor water-bearing zone of the Jinxing Hill. During 20 years of experience, the better interception effects have been gained.

Jan 1, 1988

The Cleveland Mine has an annual ore production of 400,000 tonnes at a grade of 0.79 per cent tin and 0.30 per cent copper. It is achieved by an open stoping method, mechanised overhead sub-level benching. The operation is trackless with a ramp access from all working places to the surf- ace. Broken material is loaded from the stope and development headings into diesel trucks and hauled to the surface crushing plant.

Jan 1, 1977

By G L. Simmons, K M. LeVier, R Kappes

The low potential hydrophobic state of pyrite in amyl xanthate (PAX) flotation with nitrogen is of particular interest with regard to the N2TEC flotation technology currently being used for the recovery of auriferous pyrite at NewmontÆs Lone Tree Plant in Nevada. Initially, the N2TEC system had been found to operate satisfactorily, but cyanide in the flotation mill water appeared to be responsible for a loss in pyrite recovery. This supposition was confirmed with laboratory experiments, and a program was initiated to study flotation chemistry variables by electrochemically controlled contact angle measurements. Experimental results show that activation of pyrite in such cyanide solutions can be achieved more effectively with lead than with copper. Subsequently, based on these fundamental studies, significant improvement at the Lone Tree Plant was achieved by lead activation, in which case the recovery increased to expected levels. The effect of activator is particularly significant not only with respect to pyrite depression by residual cyanide, but also with respect to collector (PAX) consumption and the initial state of the pyrite surface. Experimental results show the importance of the pyrite surface state and the rather interesting features of the activation process.

Jan 1, 2005

By Gutsche O, Kapur PC

Experimental data on the production of fines as a function of specific grinding energy consumption show that in general the energy utilisation in a choke fed high-pressure roll mill is higher than in a ball mill, but lower than in the single-particle mode of comminution under slow compressive loading. There is some evidence to suggest that the presence of water in feeds improves the energy efficiency of pressurised roll milling somewhat. Within a wide range of energy input, the size distributions of the ground product are self-similar, the logarithmic median size decreases linearly with the amount of fines produced and the inverse of the median size increases linearly with the energy spent. The production of fines as a function of energy expended follows essentially the same pattern as the one frequently encountered in media mills. The kinetics of grinding in the high-pressure roll mill can be simulated satisfactorily by modifying the standard particle population balance equation in order to account for energy dissipation in the tightly compressed bed. Common characteristics and important differences in grinding by the media mill and the high-pressure roll mill are highlighted.

Jan 1, 1993

In this paper is given a general description of the Black Star copper orebody, its relation to the lead orebodies and the controlling factors in the mineralisation.Copper ore, in the form of chalcopyrite, was first noted at Mount Isa in 1930 during the surface drilling campaign to prove the downward continuation of the silver-Iead-zinc orebodies.Details of the occurrence are set out in table 1.Other sub-commercial widths were also disclosed and examination of these occurrences showed that commercial mineralisation could not be expected within 800 ft. of the surface. It was therefore decided that further exploration was not warranted until underground workings had advanced to this horizon.Detailed surface mapping showed two small outcrops of the host rock of the copper orebody. One occurrence, 50 ft. x 75 ft., was of quartz, with leaching suggesting former dolomite. Another outcrop, further north and west of silicified shale, with low grade oxidised copper, has recently been found. Both occurrences were above the hangingwall of the main copper orebody.When the workings in the silver-Iead-zinc orebody reached No. 7 level (875 ft. below the surface) further...

Jan 1, 1953

Chief Geologist, Groundwater and Engineering Geology Branch South Australian Department of Mines and Energy The six papers submitted for consideration during this session include two dealing with techniques for measing rock mass behaviour, including permeability, in boreholes, one describing the use of surface geophysical methods to delineate pollution plumes in groundwater together with analytical modelling of the plume, and one presenting a biological tracer technique applied to the determination of the origin of water entering underground mine workings. A paper describing dewatering at a base metal mine in Queensland includes an account of the investigation techniques employed to establish a conceptual model as a basis for the evaluation of various dewatering strategies. Of considerable interest is the use of a field gravity survey to delineate a zone of highly weathered rock which forms the major aquifer at the site.

Jan 1, 1988

By Reid JG, Cutfield S

Considerable quantities of dissolved nickel are lost in the waste liquors from the QNPL nickel treatment plant. Cementation, precipitation and ion exchange techniques were investigated to reduce this loss. Ion exchange was the most successful of the procedures studied and a process for recovering nickel from stripped ammoniacal process liquors was developed in the laboratory and scaled up to plant flow volumes. The system developed uses a carboxylic ion exchange resin operated in a completely ammoniacal cycle. The regenerant is itself regenerable using existing plant, thus the only loss is the stoichiometric value of NH4+ required to displace the exchanged cations from the resin. Existing plant sand/anthracite filter beds have been adapted for use as resin columns containing 3 cubic metres of resin capable of treating effluent at a flow rate of 6000 litres/min.

Jan 1, 1978

In another paper the author described the electrolytic preparation of highly-purified lead. One of the most difficult parts, yet perhaps the most essential part, of that research was to ensure, firstly, that the purification process should be effective; secondly, that it should remain effective; thirdly, that the lead should not be contaminated during the tests that were done on it. All this necessitated periodic analyses of the lead.The purpose of this paper is to describe the work done by the author to check the accuracy of some known rapid methods for the estimation of impurities in highly-purified lead, with the intention of applying them to the control of the electrolytic process above-mentioned.METHODS ALREADY IN USEThe literature sets out accurate methods for the estimation of impurities in lead, but these methods are both lengthy and expensive. For example, the method described by Hemingway is used in the Port Pirie laboratory of the Broken Hill Associated Smelters Pty. Ltd., but it requires a sample as large as 1000 grm., and the time required to analyse a sample extends over days, and is too long to allow of quick control over a running process. This method was used by the Associated Smelters to obtain the analyses quoted in another paper by the author.

Jan 1, 1932

By D M. Weedon

This paper introduces a novel roll crusher design, which incorporates non-cylindrical crushing rolls. The use of non-cylindrical rolls enables the crusher to achieve a greater reduction ratio than is possible with conventional roll crushers. Referred to as the NCRC (non-cylindrical roll crusher), the new crusher incorporates two rolls comprised of an alternating arrangement of plane and convex or concave surfaces. The two rolls are complementary and arranged so that when they rotate the convex and concave surfaces of each roll are substantially opposed. With the rolls rotating in opposite directions at the same speed, this arrangement produces a gap between the rolls that remains approximately constant. Discontinuities on the roll surfaces provide improved angles of nip, which increase the probability of larger particles being drawn into the crusher. Initial tests on a scale prototype of the NCRC have indicated that reduction ratios exceeding 10:1 are achievable.

Jan 1, 2000

By Taylor RN

A simple apparatus for delivering pulverized coal as fuel to a SIROSMELT lance is described, and its performance in smelting tests is evaluated. Using the pulverized coal as fuel, the SIROSMELT furnace performed well in both oxidative copper smelting and reductive smelting (zinc fuming). In both cases the evidence suggests that part of the combustion occurred by indirect oxidation of coal particles entrained in the bath. Oxygen potential measurements made during the zinc fuming tests confirmed the general features of the the non-equilibrium mechanism for zinc fuming proposed by Richards and Brimacombe. The zinc level in the slag during continuous fuming was lower than was predicted using an equilibrium model.

Jan 1, 1987

The introduction of legal certification of mine managers is a matter of history. It was introduced as part of legislation for mine safety. It has been said that such legislat- ion was written in blood. Like all legislation this legislation is divided into three sections; commands, obligations and sanctions. While legislation in all States on this subject is similar, the differences are great enough to have prompted the preparation of a Uniform Code by the Annual Conference of Chief Inspectors of Mines. This Uniform Code has not been adopted fully by any State to date. Legal certification of mine managers has made managers more aware of the requirements of the legislation covering their industry, legislation that reads as a summary on past accidents and methods of preventing them. While budding managers spend considerable' time in their early years in the preparation for certification, history has shown that the industry has benefited from their efforts. A better knowledge of the safety acts by the managers has produced safer operations, and a higher standard of management has raised the technical standards of mining operations to a stage where Australia can be proud.

Jan 1, 1980

By Geoff Baldwin

The use of monitors to assess equipment performance is carried out on a routine basis in many industries. The benefits gained through process control in knowing exactly how the equipment is working far outweigh the initial capital costs of the monitor. In the mining industry several dragline monitors have been developed and installed on equipment through out the world, but to date none has been fully accepted by the industry. This paper describes the use of a sophisticated monitoring system which incorporates an onboard processor to assess both dragline and blast performance. The results of a case study are presented and an indication of the potential of the monitoring system to optimise mine production is given.

Jan 1, 1990

The value of water is defined by its marginal utility. Challenges arise where the marginal utility is difficult to estimate. Therefore, when two or more interested parties wish to access water and they cannot use commensurate units for marginal utility; other means of value comparison must be sought. It is asserted here that sustainability principles can be used to guide this valuation if this is supported by a transparent decision framework. This paper proposes that the ICMM sustainable development principles provide appropriate guidance. In addition, a generic framework for decision making is suggested as a complement. Indicators of water management are recognised widely as an integral part of the accountability of minerals companies towards meeting sustainability goals. Less widely recognised are the ways in which sustainability principles can be used to guide decisions on water management which demonstrate growing awareness of its value. This paper illustrates the use of this logic in water issues associated with global sustainability challenges. It then goes on to demonstrate, using examples, that these links exist at all levels of the minerals industry and that indicators of this type are potentially as powerful as those currently being used. The reason for this is that the path from cause to effect is transparent and direct.

Jan 1, 2006

By Whitworth NR, Fox MJ, Henley RG

The coal mass flow monitor was developed to measure the instantaneous mass flow rate of pulverised coal to the copper reverberatory furnace at Mount Isa. The instrument was calibrated with an isokinetic coal sampler which was installed immediately downstream from the coal mass flow monitor. Readings from the coal mass flow monitor were used to control the feedrate of coal to the furnace and this helped to stabilise the furnace operation.Coal samples obtained from the isokinetic coal sampler were also sized using a Leeds and Northrup Microtrac analyser. The coal size was critical to reverberatory furnace performance. These developments significantly improved the overall combustion control of the furnace and gains of ten percent were made in the furnace thermal efficiency. Testwork on an auxiliary arch coal burner is also reported.

Jan 1, 1985

By Nettle W. H V

THE past few years have seen a considerable expansion of the roasting of blende in Australia. The bulk of this blende is Zinciferous concentrate from Broken Hill and now forms a very considerable source of sulphur for the acid manufacture. It will bereadily conceded that Australian sentiment is in favour of utilising all known potential wealth, especially that won from below ground, as this once disposed of is gone forever. If Australia does not make sulphuric acid from her sulphide ores we may be sure that the purchaser of these ores will do so if in any way possible. It must not be assumed, then, that the difficulties met are mentioned with the idea of undue criticism, but rather to show that, although most of the intial troubles have been overcome, there are still a few to be encountered; and with the hope that comment brought forth will aid in the solution of the problems facing an industry at present little more than in its childhood as far as Australia is concerned.Blende roasting is done in mechanical furnaces of various makes, and mostly without the aid of other fuel than the sulphur in the ore. It will be our aim to touch on the various difficulties in the order in which they occur in the train from furnace to acid plant.

Jan 1, 1926

By Nash B. G W

In June 1976 a 600'tonne/day manganese ore sinter machine, with on-strand cooling, was commissioned at the plant of Tasmanian Electro Metallurgical Company Pty. Ltd. at Bell Bay, Tasmania. This machine was installed in order to utilize manganese lump ore screenings generated in the preparation of raw materials prior to charging to the electric smelting furnaces at Bell Bay. Since commissioning, trial sintering of a number of different grades of manganese ore fines from Groote Eylandt Mining Company Pty. Ltd, has been conducted and suitable sinter has been produced from these different grades. The sinter produced is used as part of the furnace burden in both ferro manganese production and silico manganese production. The inclusion of sinter as part of the charge in the production of ferro manganese has considerably improved furnace operating conditions and performance.

Jan 1, 1977

The mmmg operations carried out by North Broken Hill Limited, necessitate the use of four shafts for the haulage of ore, men, and supplies. These are:-1. Blackwood's Shaft.-British Section, which has 100 feet intervals between levels to the bottom 800 feet level plat;2. Thompson's Shaft.-British Section, which has 100 feet intervals between levels to the bottom 1400 feet level plat;3. No. 1 Shaft.-With intervals between levels:(a) 100 feet to the 800 feet level,(b) 150 feet from 800 feet level to the 1700 feet level;4. No. {2 Shaft.-2770 feet from collar to bottom plat, with intervals between levels: (a) 100 feet to 800 feet level, (b) 150 feet from 800 feet level to the 2600 feet level. (c) 170 feet from 2600 feet level to the 2770 feet level.All shafts have two cage compartments, and the No. 2 Shaft a skip installation in addition.For the control of hoisting operations an electric signalling system is installed on each shaft, and is supplemented by a counterbalanced rope pull ("Knocker line") operating a surface gong. The latter system is shown diagrammatically in Fig. 1.Two sets of electrical equipment are used per shaft. The first, shown in Fig. 2, is that operated by the braceman or...

Jan 1, 1940

Australia's gold mining industry has seen a resurgence in the past seven years - a resurgence the likes of which has been seen in very few, if any of this nation's other mineral industries. Industry experts are predicting that Australia could become one of the world's largest gold producers as the future of the South African gold industry looks increasingly tenuous under the present political crisis in that country. Therefore, it is utterly ludicrous for the Federal Government to introduce a tax which will see the Australian gold industry "wither on the vine."The Queensland State Government is utterly opposed to a tax on gold. Anyone in their right mind, who has seen the statistics could only agree with our stance. In 1984/85, activity in the gold mining industry is estimated to have accounted for over $750 million in national income, over$1,200 million in national output, and tax revenue of at least $115 million as well as providing more than 16,000 jobs. Chartered accountants Coopers and Lybrand's survey on the gold industry last year showed an increase in exploration expenditure by gold producers and explorers by up to 36% in 1986 from 1985 levels. That level is expected to be maintained in real terms for most of the remainder of the decade under the present tax arrangements. This is in contrast with the mining sector as a whole, where a recent Australian Mining Industry Council survey forecasted a 14% FALL in production.

Jan 1, 1986

The Rotary Kiln at TeKumi was commissioned in February 2002. The process involves burning limestone at 1000 - 11 000¦C to produce a burnt lime (CaO) product. This paper describes the design and installation of a trifoil system to improve the energy efficiency of the kiln. An energy balance showed that 32 per cent of the energy was being lost through the flue gases, compared to 5.8 per cent in shell losses and 2.5 per cent lost as heat in the product. The trifoil proved to be the best way to tap the energy from the flue gases. Drying tests showed that a trifoil improved the drying time of limestone by 37.5 per cent, compared to only 25 per cent for a lifter system. The trifoil system increases the surface area for heat transfer in a Rotary Kiln by 180 per cent. The overal energy efficiency of the Rotary Kiln was improved by 15 per cent, resulting in a 15 per cent increase in production and an 80¦C reduction in flue gas temperature. This has reduced dust build up in the ducting while reducing maintenance costs through a reduced fan speed. The trifoil hub was designed with tooths at the centre to prevent shifting. Each trifoil leg has an anchor block on the down side to prevent downward movement of the trefoil legs.

Jan 1, 2003