Search Documents

Coal Mining Land Use on the southern coalfields often preceded other land uses. Over the past century overlying land use has altered significantly, particularly with water supply storage development, road system building, railways, pipelines, electricity reticulation schemes and general urban develop- ment. National Parks were declared over coal bearing lands. Little regard was paid to the coal under the land surface by land developers, Government instrumentalities, central planners and the Metropolitan Water, Sewerage and Drainage Board and others, and little value was placed on this valuable energy source. These bodies derived no benefit from the under- lying mineral. In these circumstances, mine operators and such surface land users were put into adversary roles. Mass sterilisation of coal resources resulted. The loss of reserves continues, although the problem has become better under- stood. An Energy Impact Statement (EIS) submission by all surface land developers has been proposed as a means to justify the impact of the development on the coal reserves Beneath.

Jan 1, 1979

The grinding of ore to a size that is conducive to the extraction of minerals by leaching or flotation is an essential and expensive component of most mineral-processing operations. Overgrinding results in reduced flotability of the minerals, as well as problems in the filtration and thickening processes, while undergrinding leads to a product in which the minerals have not been exposed, and cannot be leached or floated effectively. Furthermore, coarse material causes settling in thickeners and agitator tanks. It is therefore essential, from the perspective of both operational and extraction efficiency, to grind the ore to an optimum size fraction. A well-run milling circuit will yield a product within a narrow size band and at a high throughput. Although the effective operation and control of milling circuits with their many operating parameters is widely acknowledged as a complex as well as a critically important operation, the benefits of such control are difficult to quantify. This is due to the difficulties in relating more stable operation to increased recovery of the valuable components in downstream processes.

Jan 1, 1993

By P B. Hills, R J. Walton

Narrow vein tabular orebodies are prone to mining induced seismicity. The Tasmania Mine is a complex example of a seismically active tabular orebody, where the contrasting material properties of the host strata and of the orebody itself, serve to exacerbate the seismic response. Analysis of a continuous record of seismicity over a period of seven years has provided significant insight into the fundamental mechanics of the rock mass. Understanding seismicity to permit safe extraction of the orebody has been enhanced by instrumentation of rock mass behaviour in response to mining and mining induced seismicity. It is the purpose of this paper to explore that understanding in respect to the adoption of an alternative down-hole Avoca stoping method for use in particular circumstances.Intensive instrumentation of the Tasmania Mine over a period of four years has provided insight into the behaviour of the rock mass in response to extraction of the narrow vein orebody it encompasses. A range of instruments have been installed in clusters or single installations in order to measure changing stress conditions and the impact of those changes on the rock mass and the reinforcement system.Instruments are often installed in very close proximity to active production stoping. While it has been possible to observe the impact of the mining and mining induced seismicity at very close quarters, instruments installed in these locations are vulnerable to damage and consequently, the level of instrumentation is high. Instruments are continuously logged, typically on a six hourly basis coinciding with the end of regular blasting times. The response of the instrumentation to changed rock mass conditions is considered against the background of development and production blasting and against the seismic record to assess the viability of downhole Avoca stoping.CITATION:Hills, P B and Walton, R J, 2012. Continued observations of rock mass behaviour in response to stoping at the Tasmania mine, Beaconsfield, Tasmania, in Proceedings Narrow Vein Mining 2012 , pp 169-178 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 26, 2012

By Coates D. F, Neil T. J, O&apos

A proper economic analysis of pit slope design must reflect the trade-off between the benefits and the increased risks of slope fail- ure inherent in steeper slope angles. However, no formal framework for a proper analysis existed to date. This paper describes the results of the past four years' effort in which a formal eco- nomic analysis framework was developed and tested through a case study. This framework, in essence, consists of the availability of tested procedures and com- puter programs. The procedures as well as the programs are divided into two broad functional categories; (1) the first category related to assessing the economic benefits and costs associated with various pit slope angles and (2) the second category that determines the overall financial impact which the assessed benefits and costs exert to the mine operator's overall economic stature.

Jan 1, 1977

By Hinrichsen H. D, Rathburn D. R, Stieger W

The present situation in the field of iron ore pelletizing is briefly described with particular view of the Lurgi/Dravo travelling grate process. To meet todays pellet quality requirements with regard to physical and metal- lurgical properties it is often necessary to add basic fluxing materials. It has been de- monstrated that for certain ores, basic addi- tives provide a considerable improvement in fired pellet quality. The production of self- fluxing pellets is becoming increasingly attractive. One Lurgi/Dravo plant is now in operation and another is under construction which were designed for the production of self- fluxing pellets. Self-fluxing pellets may be considered as the primary or exclusive blast furnace burden and the installation of a sinter plant is not necessary if the pellet plant-can handle all in-plant fines. Reference is made to the first pellet plant utilizing iron ore concentrate, in-plant fines and basic flux. The use of solid fuel for pellet indura- tion is discussed because of the increasing prices and possible shortages of heavy oil and natural gas. Since there is a strong tendency to increasing plant capacities, the design fea- tures of travelling grate pelletizing plants for productions up to 6 million tonnes are Discussed.

Jan 1, 1974

By Irving R. C

THE objective of the iron smelter is naturally the production of high quality iron at the lowest practicable cost. To enable this, large tonnages are put through the blast furnace, and, at the same time, the quality of the iron must be under definite control.The modern blast furnace enables these objectives to be attained. The description whieh follows sets out the general details of construction of such furnaces, and the operation at thc Broken Hill Proprietary Company's blast furnaces at Newcastle, New South Wales.The occurence of iron in many forms is so well known as to need no description. Modern civilisation may be said to be built on a foundation of iron, and, today, the production of iron and steel has beeome one of the world's industries.A short historical introduction will serve to show the evolution of the processes and apparatus since iron production assumed importance.There is no definite date fixed as to when iron was first made, or by what means it was first discovered. Perhaps prehistoric man threw iron bearing stone on to his fire, and these became reduced, Ieaving a soft metal behind, or more probably the first iron was of meteoric origin.There is evidence, however, to prove that it has been known for a period of 6000 years. Iron has been found in the Pyramids and its use was known to the early Eqyptians and later to the Hebrews, Assyrians, Greeks and Chinese. Following the Greeks, the Romans excelled in its extraction and uses in the manufacture of their instruments of war, and to this fact can largely be attributed the success of their many wars of conquest. As the Romans overran the rest of the then known world they carried the art with...

Jan 1, 1930

By Mitchell D

In recent years the need to provide increased ventilation to improve environmental conditions rather than to dilute firedamp has led to increasing interest in the use of recirculation. Present UK mining law prohibits recirculation in ventilation, but it has been permitted selectively by exemption granted by Hm Inspectorate of Mines and Quarries. The conditions of use imposed by these exemptions to safeguard the safety and health of miners are examined in detail, dealing separately with primary and auxiliary recirculation systems.

Jan 1, 1988

A mechanised sub-level overhead benching method is used at Cleveland, to produce 22,000 tons per month of ore assaying 0.92% Sn and 0.40% Cu. The ore occurs in a series of vertical lenses which can be mined by open stoping. Levels are developed at 60ft., vertical intervals by jumbos. The ore is silled out and the stope block formed between levels drilled out by long hole drilling. Each row of holes is fired and broken ore within safe reach from the stope brow is mucked out by Wagner ST-5A Scoop Trams. The remaining broken ore is recovered on extraction of the next lower level. Ore is hauled by road to the crusher station from the mine. As mining proceeds below the lowest surface portal a spiral decline will be used for ore haulage and mine servicing.

Jan 1, 1970

By Pak DL

Over the last decade computers have become an essential element in assessing the economic feasibility of mining new mineral deposits and in assisting a variety of related support functions. A broad overview is given of the many technical application areas where computers are contributing to the mining industry with reference to work being done on the evaluation of drill hole information, mineral inventory modelling, ore reserve estimation, financial analysis, process simulation, process control, workshop job scheduling, PERT applications, and com- puter aided drafting. In all these areas the computer has greatly reduced the manual effort involved in looking at alternatives. It has had a significant effect in eliminating delays in revising calculations, or rescheduling activities to incorporate new data or cater for changing conditions, while at the same time providing more accurate and prompt information for the management decision making Process.

Jan 1, 1980

By Menne D. M, Ladyman R

Camel Creek Mine operated by Lynch Mining Pty Ltd is located 65 km west of inghain and 160 kin north west of Townsville in North Queensland. (Figure 1). The Camel Creek gold mineralisation was discovered in mid-1987 in an area previously known for its tin workings. Mining commenced in January 1989 after an oxide reserve of 1.2 million tonnes @ 2.1 g/t gold had been delineated. The first gold pour was in May 1989. The mine developed into a medium sized open cut operation, with full site facilities. The initial mining rate was 500 000 tpa utilising run-of-mine (ROM) heap leaching to recover the gold. By the end of 1990 the wider orehodies were mined and efforts were focused on the narrow orebodies, of width typically less than three metres. Smaller earth moving equipment was employed to selectively mine the narrow orehodies leading to a decrease in the mining rate to 200 000 tpa. The Red Gold deposit (80 000 tonnes « 3.0 g/t to 18 in vertical) was mined in mid-1990 and ore was hauled approximately 8 kin to the Camel Creek heap leach operation. The ore was hauled in a dedicated campaign after being stockpiled. The cost of dedicated ore haulage ensured that only the more exceptional of the remote orebodies could be mined in this manner. The Golden Cup orebody, some 20 km from Camel Creek, was too distant to permit ore haulage. However, this prospect contained sufficient gold (initially 90 000 tonnes @ 3.0 g/t) to warrant the installation of a small mobile adsorption facility. Construction of the second heap leach operation commenced in late-1990. Gold production commenced in early April 1991. Mining of several smaller orebodies remote to the second heap leach facility has been undertaken and further mining is planned. This paper outlines heap leaching practice at Camel Creek Mine and summarises the success of the Golden Cup heap leach.

Jan 1, 1994

Lightweight polymer grids have recently been introduced to the mining industry. They are currently being used for roof and rib control, longwall shield recovery, safety guarding or barricade, highwall screening, internal reinforcement of gunnite/shotcrete applications, sub-base reinforcement, construction of steepened slopes, retaining walls, mine reclamation (i.e. erosion control, turf reinforcement), and in numerous mining waste related projects. These polymer mining grids utilize a strong, lightweight polymer, usually special grades of polypropylene or polyethylene. High tensile strengths are achieved by molecular orientation of these polymers in the manufacturing process. The first step in the manufacturing process is to extrude the polymers into thick continuous sheets. These sheets are then punched, and drawn into open grid structures. Aperture size and configuration are controlled by the geometry of the punched hole and the degree to which the grids are stretched. The drawing process is the key to the molecular orientation required for the tensile strengths. These long chain polymer molecules in their natural state have a random orientation. When stretched, the molecules are pulled into a parallel alignment, thus creating a lightweight product with tensile strength comparable to Steel.

Jan 1, 1992

A brief review of the problems in ventilating and cooling deep and hot Australian mines is presented. An overview is given on the development of the controlled partial recirculation concept. The main part of this paper describes the first majo

Jan 1, 1994

By Moritz P

Thiourea has been recognised for a long time as an acid-stable complexant for gold. Generally, the use of thiourea has been shown to exhibit enhanced leaching kinetics compared to cyanide but suffers the disadvantage of excessive reagent consumption. Thiourea leaching is particularly com- patible with the extraction of gold from refractory ores. This is due to the need for an oxidative pretreatment to liberate the gold. Such pretreatments typically result in the production of an acidic residue. The application of novel thiourea leaching technologies to the extraction of gold from a bioleached pyrite concentrate was investigated. The interac- tion of leach variables with thiourea consumption and gold extraction was established. An economic assessment of thiourea leaching was compared with conventional cyanidation. The results indicated that gold leaching of the bioleached residue using thiourea compared very favourably with cyanidation.

Jan 1, 1991

By Spencer P. A

Bacterial oxidation, previously known as bacterial leaching or bio-leaching, has been applied at laboratory and pilot plant scale to many refractory ores and concentrates around the world. The most common bacterial culture used in this process has been Thiobacillus sp. This organism is limited in commercial application, especially in Australia for several reasons. The optimum operating temperature range for this culture is 30¦C to 40¦C and high levels of some metals such as arsenic, silver, and copper have toxic effects on the culture thus reducing its effectiveness. The culture employed by BacTech (Australia) Pty lid is a moderately thermophilic culture which operates in a temperature range of 40¦C to 55¦C (which is more amenable to the Australian climate) and with higher resistance levels to metals often found to be toxic to Thiobacillus sp..

Jan 1, 1991

By Yates M. G, Rowlands A. T

Most geostatistical techniques applied to the estimation of ore reserves assume relatively unifonn grade and thickness within an ore deposit environment. In shear-hosted mineralisation this rarely occurs. The distribution of mineralisation is controlled by the kinematic and geometric variation within the shear zone. Although the kinematic variation is dependent primarily on the temperature (and consequently the depth) of formation of the deposit, the geometric variation appears to be relatively insensitive to this parameter. Shoot mineralisation is controlled either by the intersection of secoodary shear planes (brittle deformation) or the stretching lineation of the mylonitic fabric (ductile defonnation).Once the shear geometry is clearly identified, it is critical to review the distribution of grade and thickness of mineralisation. The practice of cutting high-grade intersections without reference to the shear model leads to underestimation of the amount of gold in the deposit. High-grade shoots may occur as pipe-shaped bodies within the system; their identification is essential for both resource estimation and mine planning purposes.

Jan 1, 1991

By Toguri JM

A solid electrolyte technique has been used to measure the activity of cobalt in liquid cobalt-gold alloys containing between 0.085 and 0.50 mole fraction of cobalt, and for temperatures from just above the liquidus to around 1550 K. The system exhibits positive deviation from ideality, both in the activities of cobalt and gold, and in the enthalpy and excess entropy of mixing. The results agree with previous measurements using a Knudsen cell - mass spectrometer technique, but differ from those reported for a gas equilibration method. The data have been used to calculate the activity coefficient of cobalt oxide in silica saturated iron silicate slags and to express the solubility of cobalt in such slags as a function of cobalt activity and oxygen pressure.

Jan 1, 1984

By Sandvik

Fine grinding in an air-swept ball mill working in closed circuit with a forced vortex air classifier has been investigated first in continuous laboratory and then in industrial scale. Results from the laboratory circuit have shown significant influence of mill load (powder filling) on the capacity of the circuit. In laboratory scale the mill load was measured and controlled by a weighing platform placed under the complete mill set-up. The mill load of the industrial air-swept ball mill has till now been controlled by measuring the power consumption of the mill motor. Thus, it was necessary to operate far from the range of optimal mill filling. To improve the circuit performance, alternative ways of mill load measurement were investigated. An important factor was investment cost, as many fine grinding mills operate in relatively small circuits that do not wan-ant large investment. In this case the task was accomplished by using a piezoelectric strain transducer, which detected strain changes in the mill shell. It was installed in the midpoint of the shell, where the highest deformation was obtained. As the transducer was on the top position, it indicated compression, and on the bottom position it measured tension. By taking the difference between the readings, it was possible to calculate total strain variations, directly proportional to the mill load. The signal from the transducer was sent to a control room via a cordless infrared communication system, employing a microprocessor control card, which could further regulate other operating parameters of the circuit according to the software model. The installation required very low investment cost and provided simplicity of application as well as stability and reliability of characteristics under severe industrial condition. The measurement system made it possible to optimise the mill load and thus increase the production from 3.2 to 3.7 dh (15 per cent), and stabilise the circuit operation.

Jan 1, 1995

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

A simple production technique has been initiated and implemented at Oaky Creek open cut coal mine to optimise recovery of coal from the relatively thin geological seams. The production technique is based upon minimising coal dilution through careful dragline operation and the selective use of mine mobile equipment to clean the top of coal. In addition, recovery of coal from the pits has been increased by refining blasting and dragline methods.The implementation of the recovery optimisation programme at Oaky Creek has provided significant economic benefits from increased yield through the preparation plant by the reduction in dilution, and from increased raw coal tonnage through improved pit recovery methods.

Jan 1, 1990

Draglines have been a significant part of world open cut mining since the early part of the 20th century particularly for the removal of overburden in the strip mining of coal. Since the mid-1960s draglines have played a major part in the large strip mining coal developments of Queensland and New South Wales.There are now over 60 large draglines operating in Australia ranging in size from 23 to 103 cubic metres bucket capacity, with digging depths to 60 metres, dumping heights to 50 metres and dumping radii to 100 metres. The application of these draglines has progressed through the uncovering of coal in shallow, single seam operations to deep multi-seam operations requiring a greater dependence on pre-stripping activities ahead of the dragline to remove overburden not able to be efficiently handled by the dragline.

Jan 1, 1992