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By de Lassar de Pressigny Y

IRSID has in its laboratories two experi mental counter-current reduction furnaces allo- wing the simulation of the physico-chemical conditions of reduction in any gas-solid coun- ter-current process, including the blast furnace and direct-reduction shaft-furnaces. The counter current is realized by an electric furnace mo- ving along a laboratory tube filled with the material to be tested. The reducing gas stream in the tube travels in the same direction as the furnace After reduction, twenty samples, with dif- ferent degrees of reduction and which can be related to different levels of an industrial furnace, are taken from the tube and subjected to various quality tests. Experiments were realized to determine the behaviour of various types of industrial pellets when reduced under either blast furnace or shaft furnace conditions. The results show the large influence of the reducing conditions on any pa- rameter characteristic of the quality of the pellets : reduction efficiency, swelling, cru- shing strength and disintegration.

Jan 1, 1974

FOR some time past keen interest has been shown in both America and South Africa in the mining drill-steel problem. This interest has extended to Australian mining fields, and Australian drill users, ever desirous of increasing efficiency, are vigorously attacking the problem. The writer has recently been engaged in the investigation of the problem on two of ,the biggest mining fields in Australia, and has formed very definite conclusions concerning the causes of many drill-steel casualties. He puts these views forward in the hope that they may be of interest to, both drill manufacturers and drill users. The subject is here dealt with mainly from the aspect of the properties of the steel and the modifications of these properties whensubjected to various manipulations. It is generally admitted that the drilling machine has greatly increased in power and efficiency during recent years, and the consequence is that the machine is demanding better service from the steel. This is being impressed on the drill users by an increase in steel casualties. This fact has led many mining people to the view that the machine has developed so rapidly that the steel maker has not been able to keep pace, and that consequently the steel isfailing by fatigue 0:1; so-called crystallization. This view is rather depressing. The writer, on the other hand, is inclined to discountenance fatigue as a serious factor under good normal working conditions where the steel is carefully manufactured and supplied to the user under suitable structural and sound conditions, and has subsequently received kind treatment at the hands of the drill sharpener and the drill user.It is not reasonable to attribute failures to fatigue until it has definitely been proved that the steel is fundamentally sound and is in the best structural condition to resist the stresses it is called upon to withstand, and, this being so, that all fundamental principles of...

Jan 1, 1923

By Costello MC

An alternative process for desorbing and recovering metals from activated carbon has been developed, and is the subject of several patent applications by Micron Research (W.A.) The system uses the principle of conditioning the carbon in a strong alkaline cyanide solution followed by distillation desorption in a fractionating column, using the carbon as the column packing and methanol as the desorbing agent. The system offers the following advantages : (a) The processes of desorption, methanol recovery and reactivation are all carried out in a single column with the carbon itself acting as the column packing. No other desorption plant items or fractional distillation equipment are required. (b) The metal values are concentrated into the water content of the carbon and no other water is used except as condenser coolant. This produces very high grade gold silver solutions which give high current efficiencies in the electrowinning step. These high gold concentrations allow almost complete separation of gold and silver from copper in the electrolytic cell. (c) The process is completed to a tailing assay of less than 200g Au/tonne carbon in 15 - 20 hours allowing turn around of carbon batches on a daily Basis.

Jan 1, 1982

By Paine GG

The in-situ retorting of shallow oil shale deposits is an attractive alternative to the material handling problems of conventional open pit mining techniques, which involve removing overburden, fragmenting and transporting the shale to a fixed retort, and finally disposing of the hot spent shale.For in-situ retorting to be successful, the oil shale has to be fractured and the fragmented rock expanded into a void, to allow controlled propagation of a flame front through the in-situ retort. The principles of cratering with explosives have been used to develop a process for the in-situ fracturing of a thin oil shale deposit overlain by a formation of porous rock. The overlying porous rock formation is first compressed by explosive charges to create voids in the porous rock. The oil shale is then fragmented and pushed in to the voids with separate explosive charges. This paper discusses methods of creating voids in porous rocks with minimal surface disturbance, and then methods of obtaining the most uniform fragmentation of the shale. The whole process can be completed, in practice, in one blast. The results of an experimental blast are presented, and possible modifications are then discussed.

Jan 1, 1985

By Townsend IJ

The Upper Triassic Leigh Creek Coal Measures which include a number of seams of sub-bituminous black coal are preserved in four small intramontane basins. The largest is Telford Basin, 1,000 m in thickness. The coals, of variable thickness and quality, are mined by open cast mining methods and utilised for generation of electricity at Port Augusta. The combined proven and indicated reserves are about 100 million tonnes.

Jan 1, 1975

Answers to many questions arising in the different phases of exploration, estimation and production of a mineral deposit, can be found in the geostatistical theory of G. Matheron. It is shown that all these questions regarding sample size, number of samples, shape of drilling pattern can be answered as soon as the continuity of the mineralization is quantitatively characterized by means of a variogram. Next a formula which gives the variance of the error associated to any estimation procedure (i.e., any method and any sampling pattern) is given. Applications to the computation of the standard error of the'mean for various sampling patterns are shown, as well as how to use the formula to simulate several possible sampling strategies and choose the best one. Altogether it is shown how to answer the often heard question, "what happens if such and such sampling procedure is used?", rather than giving an hypothetical "optimal" solution.

Jan 1, 1976

By Soma T

Pyrite and Cu-concentrate were roasted in vertically suspended state in an externally heated tube. Tubes of three different lengths of reaction zone were used for three different reaction times. Roasted ores were submitted to chemical analysis and the extent of roasting reactions was determined. In case of pyrite, extent of roasting reactions was not affected much by reactor length and heating temperature (above 500¦C), but was considerably by ore/air ratio. Micro- scopic and XMA examinations led to the conclus- ion that pyrite particles decomposed to pyrrho- tite and then pyrrhotite was oxidized to give Fe-S-0 melt, magnetite and hematite. The extent of reaction was not uniform in all particles but had a wide distribution from unreacted pyrite to completely oxidized particles. Combustion of Cu-concentrate from Kuroko complex sulfide ore ) was unstable under a uniform wall temperature of 450¦C, but proceed- ed rapidly at temperatures above 500¦C. Sticking of roasted ores to the wall of the reaction tube induced choking of the tube, caused by melting of roasted ores, at tempera- tures above 950¦C. Enrichment of oxygen exterted less influence on reaction rate than heating temperature of the tube. Particle size of ore had a big effect on reaction rate.

Jan 1, 1980

Carbonate-hosted massive sulfide ores of the American cordillera compose a distinctive genetic class. Discordant fea-tures of occurrence together with measured high-temperatures of formation indicate their essential epigenetic character and close spatial association with centers of thermal activity during evolution of the cordillera. Their metallogenic character is complex from region to region: Cu-Zn-Pb-Ag, Pb-Zn-Ag, and Cu-Zn-Ag-Au represent extremes of composition and each may be identified with specific terranes of occurrence, notwithstand-ing an inferred common process of formation. Beyond the presence of a thermal center, other controls that may be identi-fied include apparent but obscure properties of primary perme-ability or chemistry of hosting strata, and secondary controls are imposed by stratigraphic differences in which permeability is strongly contrasted. Structures that act as channelways may be identified in some instances. Notwithstanding their intrinsic value, search for these ores is difficult and requires the solution of complex geochemical and three-dimensional geometric problems.

Jan 1, 1990

By D K. Miller, L W. Armstrong

In April 2006, Orica Quarry Services undertook an investigation to determine the likely vibration and frequency response of three water storage tanks to quarry blasting, immediately adjacent to the tanks. Of the three tanks that were studied, two are relatively tall with a æwineglassÆ shape; one is constructed of steel (4 ML storage capacity) while the other is constructed of concrete (2 ML storage capacity). The third is a ground-embedded concrete tank that is relatively squat and broad in shape (38 ML storage capacity). A vibration limit of 25 mm/s and an acceleration limit of 0.16 g were imposed on the tanks. However, this report shows that this acceleration limit, whilst having relevance to low frequency earthquake motions, is quite inappropriate for the high frequency blast vibrations that are typical in a quarry blasting environment. The investigation involved firing 11 single blastholes of known charge weights and distances from the tanks, and measuring the tank vibration response using blast monitors placed on and around each tank. Analysis of the data collected from the cement tanks showed resonant responses over a broad range of frequencies, with dominant and lesser responses in vertical and lateral motion recorded at 9.8 Hz, 12 Hz, 16.8 Hz, 17 Hz, 31.3 Hz and 38.1 Hz. Unfortunately, most of the data collected on the steel tank was corrupted by noise due to electrical sources and/or mechanical sources such as the water agitator inside the tank. Advanced Monte Carlo vibration models were then constructed using the single blasthole information. Knowing the resonant frequencies enabled the modelling of electronic delay sequences for the reduction of resonant vibrations. Ultimately programmable and accurate electronic delay detonators were deemed essential to allow blasting in relatively close proximity to the tanks while avoiding resonant frequencies. Three blast designs were modelled, ranging in maximum instantaneous charge (MIC) from 4 kg to 22 kg, and 60 holes to 160 holes. The modelling showed that two of the designs (using small charge weights) could be used no closer than 71 m from the storage tanks. This is based on a 90 per cent confidence level of achieving vibration levels within the 0.16 g acceleration limit, even though the velocity levels predicted to be generated at this distance were significantly less than the 25 mm/s limit. The third design incorporated larger charge weights and could be used for blasting at distances no closer than 220 m from the tanks. The present work, conducted in an operating quarry, demonstrates the usefulness of Monte Carlo waveform superposition techniques for the control and reduction of ground vibration (either velocity or acceleration) under restrictive environmental constraints. However, a discussion is also presented to demonstrate that it is somewhat restrictive to impose an acceleration limit based on the motion produced by low frequency earthquakes rather than the motion produced by high frequency blast vibrations.

Jan 1, 2007

The overall systems approach to blast furnace aerodynamics is explored including the time and spatial inter-relationships that exist between the furnace lines, tuyeres, burden characteristics, distributor capabilities and furnace operating practice. Attention is called to the time dependent, three dimensional aspects of blast furnace aerodynamics and to the existence of several zones within a furnace where the flow characteristics are different. Changes in furnace operating practice to take further advantage of fully beneficiated burdens including formed coke are discussed from a practical viewpoint. Lessons learned in a variety of shaft furnaces used for other purposes are discussed insofar as they have a bearing on aerodynamics in an iron blast furnace. Questions are raised about the penetration of hot blast in large furnaces. Operating practices and.proposed solutions are evaluated where tuyeres over iron and slag notches are restricted or plugged. Opportunities are presented for using on-line hierarchical computer systems with adaptive tuning algorithms to provide non-linear control of changing process conditions in real time. This will make it possible for the blast furnace operator to optimise a variety of interrelated paramaters, each with different response times. Potential increases in productivity, fuel savings and improved quality control are believed to be within reach.

Jan 1, 1975

By Andersen AK

As part of a research program sponsored by Continental Copper and Steel Industries, Inc. (cos), investigations have been conducted by the Colorado School of Mines Research Foundation, Inc. to study the effect of high current densities on electrolytic processes. The importance of high current densities has long been recognized, particularly in the deposition of copper, and the results of considerable research on the subject have been reported in recent years (19 29 39). This is not surprising because, besides plant capacity, current density is the other major factor which will determine the process economics. In the production of electrolytic copper, current efficiency, steam consumption, number of cells, building area, metal inventory, cathode purity, and power consumption are all affected by current density. The ability to maintain a high current efficiency and satisfactory cathode purity while increasing the current density to twice or three times that commonly practiced could result in considerable saving of capital investment and reduce the operating cost per ton of metal produced. The optimum current density i.e., that current density of which production cost would be at a minimum, can be established from an analysis of the various inter- relating factors (49 59). A review of.all operating electrolytic plants (electrowinning and electrorefining) will indicate that most of these plants are operating at 50% or less of the optimum current density (6). One of the reasons for not using the optimum current density may be attributed to the fact that conventional electrolytic tank- house equipment does not perform satisfactorily at high current density operations. Various investigators (19 79 8) have attempted to overcome this limitation by modifying the design of the electrolytic cell, virtually unchanged since it was first introduced in the late 1800's. Previously, these attempts have not resulted in,a cell design suitable for commercial application. However, recently, a cell has been designed which performs efficiently under such conditions. This is a CCS development (patents applied for).

Jan 1, 1969

Comminution Kinetics equations are developed to take into account difference of grindability of mineral components. The equations describing both batch and closed circuit grinding or crushing processes are given. These equations are applied to industrial data to derive comminution kinetic and classification characteristics of the component minerals in a multi-mineral ore. Control strategy based on these concepts is presented.

Jan 1, 1985

In reviewing recent developments in the process mineralogy of gold it is convenient to distinguish between visible (>0.1 pm) and invisible gold (1 - 2 pm in size in polished section; these can scan the surface of a polished section, identifying the gold minerals, recording co-ordinates of the grains for subsequent examination, and making measurements of areas and sizes of the grains. However, problems of sample reliresentivity in polished section mean that such data may not give good quantification of gold mineral proportions and liberation/locking characteristics and other methods are required for this (amalgamation, cyanidation, ultra-fine milling and cyanidation). Characterisation of invisible gold in bulk material (eg a sulphide concentrate) can be done by mineral separation, ultra-fine milling and cyanidation or by quantitative point analyses of a large number of mineral grains. Analytical methods include electron microprobe analysis (detection limit normally -200 ppm but -10 ppm by using special techniques), ion microprobe analysis (secondary ion mass spectrometry - SIMS; detection limit -0.2 ppm) or proton microprobe analysis (PIXE; detection limit

Jan 1, 1992

By Mousset-Jones P, McPherson M. J

Underground airways are characterized by irregular shape and uneven surfaces including large-scale natural roughness, fractures, and a super-imposed sand roughness. Swirls in the grooves of the wall and separation because of the periodic variation of the open cross sec- tion, due to the blasting patterns, make it almost impossible to calculate average con- vective heat transfer computationally on the bases of the geometrical description of the surface. However, dimensionless friction factors can be used to characterize the surface effect of an airway and an analogy between heat and momentum transfer can be applied to calcu- late an average convective heat transfer Coefficient.

Jan 1, 1988

There is no other effective way for study ing firedamp and coaldust explosions than to produce controlled explosions in a pre-monitor- ed environment - either mine openings kept for the purpose, or special surface galleries. Such explosion testing facilities have been employed historically at Buxton in U.K., with lesser known installations at Bruceton, U.S.A., Tremonia, West Germany, Katowice-Mikolow, Poland and elsewhere. Both firedamp and coal dust explosions are studied. Normally coal dust explosions are initiated by somewhat standardised methane air mixtures, by explosives, or purely by coal dust. Various structures and suppression installations are installed in roadways and galleries prior to explosion to simulate destruction and suppression, and the results of such tests form the basis of suppression installations, especially stone dust barriers and water barriers. Other data collected from these experiments include rev- ersals of explosion waves, pressures and temperatures and duration of explosion waves, analyses of aftergases etc. Other uses of explosion testing galleries include testing of explosives, electrical equipment and frictional . sparking.

Jan 1, 1981

By Takiuchi T, Kurita M, Owada S

This paper describes the possibility of the application of flotation to the separation of monazite from xenotime and of columbite from ferberite, which have been said to be difficult with generally used physical beneficiation methods. For Malaysian monazite and xenotime samples, a great difference is observed between the flotation recoveries at pH 7.5 using 1.0 x 10-4mol/1 dodecylammonium chloride (DAC). The grade and recovery of columbite in the binary flotation with both minerals result in 85 per cent and 67 per cent in the cleaning froth and 91 per cent and 51 per cent in the re-cleaning froth, without adding any scavenging stages. For monazite samples from various localities, the flotability is dominated by the electrostatic interaction between mineral surface and collector ion using DAC as collector, but the singular decrease of flotation is observed in the sample of which the crystallinity is low and the surface structure is rugged and complex. Otherwise, ferric ion in the flotation system probably dissolved from mineral is found to activate the flotation using sodium dodecylsulfate as collector. For columbite and ferberite, the separation is judged possible at pH 3.0 using 1.0 x 10'3mo1/l sodium oleate (NaOl) from the single flotation results of each mineral. In the binary flotation, however, columbite recovery in the froth is greatly diminished below that expected. This would be because NaOl is prevented from adsorbing on the columbite surface of which the charge is transformed more negative side by the specific adsorption of the tungstate ion dissolved from ferberite.

Jan 1, 1993

By Ruschitzka C

The productivity and economic success of a German hard coal mine is attributed to the high productivity of a small number of operation points; however high rates of production are associated with increased gas emission at the working sites. Therefore modem high technology is required in order to reach the planned production rate, since high methane concentrations often cause unplanned breakdowns in operation. The optimised simulation of gas emission is a fundamental planning tool for mine design as well as for determining the potential of a coal deposit and has increased in significance over the last years. Methane-INFO enables the three-dimensional, graphical simulation of a working site taking account of different aspects such as the mine design, ventilation, production rate, geology, seam quality, gas exhaustion, etc. The following paper gives a short overview over the benefits of the discussed system.

Jan 1, 1995

Diamonds have been known in Australia for many years, especially in association with alluvial gold and tin occurrences. Exploration for primary sources in the Kimberely area of Western Australia has been carried out since 1968, culminating in the discovery, in 1979, of the Argyle Kimberlite No 1 (AK1) kimberlite pipe. Various techniques have been used in the search for diamonds such as geologic interpretation, aerial photography and Landsat, soil geochenical techniques, geophysics, and stream sediment sampling. Stream sediment sampling, a method developed in South Africa, using the detection of indicator minerals derived from kimberlites in gravel samples, has had wide application and success in Australia. Nevertheless, although Australian diamond bearing kimberlite and lamproite rocks contain some of the classic indicator minerals, their concentrations are generally much lower than in South Africa and Russia. Despite this paucity of indicators, stream sediment sampling is still the best known and most commonly used method of diamond prospecting in Australia. Small samples are treated by hand but larger samples require the use of diamond pans, jigs or heavy media separation plants. Each of these methods has advantages and disadvantages. The final concentrate is passed over a grease table or subjected to x-ray sorting.

Jan 1, 1984

By Horrocks KRS, Smitham JB, Ellison JF

This paper describes the development and installation of equipment for continuously measuring separating density in the dense medium cyclone circuits of the four million tpa Port Kembla B/C plant coal washeries. Monitoring equipment consisting of magnetic coils and differential pressure cells were installed in U-tubes taking the full flow of magnetite from the drain sections of the product drain and rinse screens. The monitoring equipment measures overflow magnetics concentration and overflow density continuously and has operated since 1989. From these measurements and calibration trials, the separating density of operating cyclone modules can be inferred reliably. Variographic analyses of the data show that medium density control to +/- 0.002 RD units and separation density control to +/- 0.007 RD units are achievable. Either method for measuring separation density can be used with approximately the same accuracy, although the overflow density measurement technique suffers from the need to have regular flushing of the Dp cells which complicates the signal analysis. Data from the plant shows that separation density can be controlled by regulating medium density, but the assumption of a constant offset between medium density and separation density is erroneous.

Jan 1, 1993

By Stewart R. D, Lawrence W, Youl M. J

The trend towards contracting by major coal mining companies such as BHP Coal and MIM Ltd is examined. Reasons why this trend is occurring are discussed and the concept of partnering is examined. Two case studies are given: the Mt Owen Mine in the Hunter Valley, NSW and the South Walker Creek Mine in the Bowen Basin, Queensland.

Jan 1, 1997