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The seam gas content at Westcliff Colliery is 12-15m3/tonne of coal.Composition ranges from 99% CH4 to 52% C02 in one area. Desorption rates are proportional to gas contents and CH4 is preferentially desorbed. A crushed zone of reduced permeability advances with the face - at Westcliff ribside crushed zones are 2.5 to 6.5m wide. Poor strata control widens crushed zones. 12 months of pre-drainage allowed 2 heading development and longer pillars to be used in a virgin area instead of 3 or more headings without drainage. Machined coal may lose as much as 1.6m3/tonne being conveyed out of Westcliff Colliery. Experience differs from mine to mine. Permeation is affected by time, strata movements, changing water content, and changing stress. Permeabilities vary from lOmd for Pittsburgh Seam to less than 1 and for the Bulli Seam. All these data and differences await further investigation.

Jan 1, 1982

A biological column leach testwork program was undertaken on a chalcocite ore. Three tests were conducted in all, using 65 in x 100 mm columns in three sections. The tests were started with varying acid strengths and inoculated with bacterial solutions from previous column testwork. The leaching of Cu was found to occur in three stages. These stages consisted of direct acid leaching, bacterial oxidation and ferric iron leaching. These leaching stages can most easily he described through the examination of not only Cu dissolution but also Fe dissolution and its subsequent oxidation and precipitation. The p11 of the system was found to he critical in establishing and maintaining the bacterial leaching system. The oxidation potential was seen to he influenced by the leaching system as the oxidation states altered. Test variables such as, 02, COz, and temperature were all found to influence the system. Final copper recoveries were in excess of 90 per cent in each column test over a leach time ranging from 211 to 328 days. Given similar leach conditions are applied, the application of this technology to site is expected to give comparable results.

Jan 1, 1994

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

Preliminary petrographic investigations of eight Upper Permian coal seams of the Muja sub-basin, Collie Coalfield, reveal that the coal is high in inertinite and relatively low in vitrinite and exinite contents. The exinite content of Collie coal is relatively high when compared to other Australian coal of similar age. In addition the mineral matter content of the coal is very much lower than comparable Permian coal of Eastern Australia. The higher exinite content could be attributed to the type of Glossopteris flora, and the lower mineral matter content to the environment of deposition postulated for the Collie Coal Measures.

Jan 1, 1982

By Virtanen M

Grinding has been one of the areas of major development at Outokumpu's concentrators. During its early years the company used entirely rod and hall mills, but due to the high costs of metallic grinding it began the testing of autogenous grinding as early as the 1950s. In the late-1970s, the company's own modification for two stage autogenous grinding was ready for industrial use. Surprisingly late, in the 80s - 90s, an interest rose to check also the effects of grinding methods on flotation results. This paper firstly gives a short history of the development work of Outokumpu type autogenous grinding, called 'Outogenius'. The effects of some grinding methods on the process results of two nickel ores are then reviewed. The tests to date show notable effects of grinding methods on flotation.

Jan 1, 1996

By Van Deventer J S J

The first step in the design of a process to treat a possible economic precious metal deposit should be an examination of the mineralogy of the ore. Using this and other initial tests, the extractive metallurgist can design a process to treat the ore. In the field of precious metal metallurgy, little emphasis is placed on the mineralogical information available to the metallurgist. The information is of far more use to the geologist and the mining engineer. Diagnostic leaching was designed to open up the field of mineralogical analysis to the metallurgist. When a mineralogist looks at the deportment of gold in an ore, he is usually looking for an element which is present in parts per million, so that errors in sampling are multiplied dramatically. Diagnostic leaching offers a cheap, simple, practical alternative. In order to determine with which minerals the desired precious metal is associated, a specific mineral is first eliminated using a selective oxidative leach, and cyanidation is used to extract the precious metal (in this case gold and silver) liberated by the destruction of this mineral. The precious metal extracted can be measured in solution to give a fairly accurate record of the amount of the precious metal associated with that mineral. Furthermore, the residue from this first stage can be subjected to another selective acid leach, and the process repeated. The procedure can be varied to suit the mineralogy of the matrix material. At the end of this diagnostic leach the metallurgist is left with a complete record of the deportment of the precious metal. He can now use this information to design a metallurgical flowsheet to treat the ore. Diagnostic leaching is thus an analytical tool which can be used by the metallurgist not only to examine new ores, but also to look at problems occurring at existing plants. The procedure is not only limited to ores and residues but in fact can deal with any type of intermediary product that occurs on a plant. The information gained from analysing an intermediary product can give a useful indication of how well a unit process is working, eg flotation, roasting, etc.

Jan 1, 1992

Some mqre facts and inferences are presented in amplification of a recent paper on the geology of the Kalgoorlie Golden Mile stressing the volcanic origin of its rich gold ores, some of which are considered tobe exhalites. Previously unpublished and largely unmapped pyroclastic features in carbonated and chloritized, but not in amphibolitic, country rock are brought to attention. This applies particularly to the main host, viz. the relatively coarse-grained quartz dolerite greenstone (Q. D. G.), i.e. Golden Mile Dolerite, and gives more credibility to the spatial association of the rich Green Leader and telluride ores with bodies of sediments and tuffites occurring within, or adjacent to, Q. D. G. There may be an intrusive relationship with contiguous mafic amphibolites of doleritic origin, but this is not certain and can only be resolved by morecomprehensive mapping than in the past. Volcanic features have always been recognized in CalC Schist, i.e. Paringa Basalt, more so recently in the shape of coarse volcanic breccia.Iu the subsequent deformation of the gold ores since their inital emplacement there appears to be a structural parallel with some Canadian base-metal deposits, most of them of volcanogenic origin.

Jan 1, 1976

By Evans A. F

Arising out of the increasing demands for efficiency in modern ore-dressing operations has grown a requirement for fuller knowledge of the characteristics of the ore treated. In part, this is being met by improved methods of study of the mode of occurrence of the constituent minerals, and of the intricacies of their physical relationships.A typical instance of the need for such a study is the presence of some undesired mineral in a flotation concentrate or tailing, which may be due either to mechanical association through insufficient grinding, or to incomplete separation in the flotation operation.Again, with modern practice in fine grinding, which often requires that from 70% upwards of the ground ore shall pass a 200-mesh screen, it is obviously impossible to obtain data on comparative grinding efficiencies, for instance, unless there is adequate knowledge of the size-composition of the material passing the finest available screen.Studies like these can be made satisfactorily only after size-separation (which may be carried out conveniently by elutriation) and by actual visual examination with the aid of a microscope, and the minute size of the mineral grains to be examined has necessitated the development of a new technique of sizing and microscopic examination.

Jan 1, 1932

By Barclay C, Jacobsen M, Towsey C

The Emperor Gold mine at Vatukoula, Fiji, is a nine million ounce gold telluride deposit. In January 1992, the mine was on the verge of closure when the current management team took charge. Losses had been incurred for two consecutive years and the published resource amounted to less than five years of production. Relationships with the workforce, the government and the general public were poor. Today, the mine has recorded three consecutive years of profit, has resources that will support the operation for at least 20 years and has excellent relationships with employees, government and the general public.

Jan 1, 1997

By Corbett GJ

Comparisons between individual SW Pacific Rim gold deposits have facilit-ated proposal of a new classification of porphyry-related mesothermal gold deposit types. Carbonate base-metal gold systems form at relatively high crustal levels, peripheral to porphyry intrusions. There is a spatial assoc-iation with major structures which focus fluids from degassing porphyries at depth. Milled matrix intrusive breccias and extrusive maar volcano/ diatreme breccias form as a result of pre-mineralisation phreatomagmatic eruptions. These focus degassing magmatic fluids by the provision of fracture ground preparation, typically within competent host rocks, adjacent to the breccia bodies. Local dilational structures control the form of individual deposits which may contain bonanza gold grades at sites of fluid quenching and/or repeated mineral deposition.Early quartz veining and porphyry-related alteration is common and later gold mineralisation typically occurs in association with carbonate veining and Fe and base metal sulphides as Zn > Pb > Cu. The progressive cooling by mixing of the upwelling mineralised magmatic fluid with descending bicarbonate waters, produces characteristic zonations in carbonate compositions. These vary with distance from the porphyry source, from Ca through Mg, Mn and distal Fe types. Gold mineralisation is preferentially distributed within the Mn/Mg carbon-ates.

Jan 1, 1994

This paper carries on from an earlier paper 'Cemented fill practice and research at Mount Isa' and reports further on the laboratory programme at Mount Isa to develop a cheap cem- ented fill using Company waste products. The practical economic significance of availability of cheap cementing agents is re- viewed, with the various alternative approaches available The basic approach adopted within this paper is that use of reactive pozzolans such as ground slags to replace a proportion of the Portland cement in the fill can make mining methods employing cemented fill more economic- ally competitive with other mining methods.

Jan 1, 1973

The extraction of the values from gold bearing clay or clayey ores has always presented difficulties. A description of the successful operation of a mill working on material of this nature is here given in the hope that it will be of interest to mining engineers and metallurgists, particularly as the ore body referred to has been worked out. The methods finally adopted were evolved at the mill after the failure of 3: plant specially designed in England and sent out to New Guinea to cope with the clay by the old principle of calcining to brick followed by crushing and cyanidation. A description is given of the direct cyanidation of run of mine ore in '90 ton vats; which was finally adopted after a great deal of study and experiment. Mention is also made of the method of removing overburden in the open cut and the mining and transport of the ore from the open cut to the mill. The purpose of the paper is to record these matters while the information is still available. . .DESCRIPTION OF THE ORE BODYThe values occurred in a flat-lying lode which had slipped about half a mile down the mountain side and had come to rest in the nearly horizontal position in which it was found and worked. The thickness of the deposit varied from a maximum of about 25 ft. at the northern end to about 10 ft. at the southern end. The ore body was capped with an overburden of decomposed breccia and porphyry of variable thickness the maximum being about 65 ft. The underlying rock, or the footwaIJ of .the flat ore body was breccia locallyknown as blue breccia.

Jan 1, 1951

By Ross J. F

A pillar 'is a block of coal left in the first working of a coal seam for the purpose of supporting the superincumbent strata in such a manner that the winning out roadways will be safe to traverse by men and by the coal transport system.PRINCIPLES OF PILLAR EXTRACTION.The size of a pillar is chiefly dependent on the depth of cover, and in a lesser degree on the nature of the coal, or the condition in which the seam has been laid down. In a seam at 1,100ft. depth of cover, and assuming a spec'ific gravity of 2.5 overall for the cover strata, a pressure of 1,200lb. per sq. in. is the loading on the top surface of the coal seam before mining begins.When mining commences, and as the pillars are formed, an increased load is imposed on the coal left in the pillars, according to the percentage of coal extracted in the first working. Thus, if 25% extraction is taken in the first working, the load on the pillars is theoretically increased from 1,200lb. per sq. in. to 1,600lb. per sq. in. over the area mined. If this state of things went on indefinitely it would not be possible wholly to extract a pillar because of the extreme pressure tliat would be thrown on the diminishing portion; but, fortunately, another element, that of time, enters into and assists the process of extraction.If the superimposed strata were of an entirely plastic nature, this time factor could not operate, as the cover weight would settle instantly on the remaining portion of the p'illar and finally overwhelm it. The cover strata above a pillar generally have a certain rigidity which does not allow the superimposed weight to settle instantly on the pillar fraction, and it requires a period of time to elapse before the extra weight is felt by the pillar.The time factor varies widely, and is governed entirely by local conditions; it can only be determined by experience gained on the spot or in close proximity to the area of operations. It is dependent on the strength of the strata and its characteristics under bridging conditions.It is, therefore, logical to assume that the more rapidly a pillar can be extracted the greater will be the safety factor and also the percentage of recovery of coal.Up to the present time, the operation of the extraction of pillars in this country has been, with a few exceptions, a manual one, and before mechanization of Collieries can be fully accomplished, the process will have to be performed mecharrically.

Jan 1, 1947

While, in the past, a great deal of attention has been focussed on technical issues and the performance of explosives in rock, the explosive user, an essential link in the chain, has often been neglected. In the mining industry, too often, the benefits of excellent technical work have been degraded over time due to the lack of definitive and documented control. Using the principles of quality management a quality training system was developed and implemented for management of explosives use at Gunpowder Copper Ltd (GCL). This paper describes the structure of the system, its development and implementation, and contains practical advice and information for managers responsible for blasting and charge crews. The paper is in four parts: I Quality systems. A brief overview of the relevant aspects of total quality management that apply to explosives use. The requirements for documentation, management and auditing are explored. 2. Training for competency. The five essential elements of Competency Board Training (CBT) are examined, including auditing. 3. The Gunpowder Copper system. Implementation of the complete training system. Documentation and its control, auditing, instructions for operators, management responsibility and means of obtaining operator ownership are amongst the issues raised. Reporting requirements are the means to effectively manage change are described. 4. Summary. The paper concludes with the tangible benefits seen by Gunpowder Copper through the adoption of a quality training System.

Jan 1, 1995

By Coulborn W. T, Glasby G. P, Maylan M. A

Research cruises by HMNZS 'Tui' (1986) and RV 'Moana Wave' (1987) investigated the geology, geophysics and seafloor mineral resources of Manihiki Plateau in the central Pacific Ocean.Manihiki Plateau is a large (500,000 km2) mid-ocean platform that rises 3000 m above the abyssal plains of surrounding ocean basins (depth -5500 m). Its foundation evolved about 112 Ma ago by massive outpouring of basaltic lavas at a plate triple junction. The plateau is blanketed by a 900 m thick sedimentary section comprising (i) mid-Late Cretaceous volcaniclastic sandstones / siltstones grading upwards to limestones / chalks and (ii) -500 m of Tertiary nanno-foram chalks and oozes. Cores from DSDP 317 drill-site on the Manihiki High Plateau indicate that the volcaniclastic sediments contain native copper and some thin beds rich in organic carbon.

Jan 1, 1990

By Olson H, Kincaid R

The marine portion of the Pacific Basin and Rim constitutes a significant part of the world's surface in which the mineral resources are virtually undeveloped. Indications of substantial resources have resulted in speculation and uncertainty with regard to their potential in the near term. The main issues are centered on the markets for the resource materials, the technology needs for their recovery, and the possible impacts of their development on the environment. While the governments of Japan, France, the Soviet Union, India, China, and Korea are financing new programs in deep ocean mining, the US is consolidating its early leadership by the continuation of NOAA's authority under the Deep Seabed Hard Mineral Resources Act and the Sea Grant Act, Interior's authority under the outer Continental Shelf Lands Act, and by the development of a new Marine Minerals Technology Center within the Department of Interior's mineral institutes program, managed by the U.S. Bureau of Mines. The Center has a Continental Shelf Division (CSD) located in Mississippi, and an Oceans Basin Division (OBD) located in Hawaii. Research and training in the divisions is directed toward the practical aspects of mineral recovery from the nearshore and deep ocean environments with a strong bias for the OBD toward industrial and international cooperative programs in the Pacific Basin and Rim. In terms of resource development, the marine minerals in the Pacific Basin may be favored in some cases, in competition with land sources, by political and environmental considerations.

Jan 1, 1990

By L C. Thompson

Biomineralisation is the process by which microorganisms mediate and catalyse inorganic reactions so as to form new mineral assemblages. The goal of biomineralisation as a remediation tool is to control microbial processes and their environment so as to sequester and immobilise specific toxic metals within exceptionally strong bonds of neo-formed mineral assemblages. In this way, the bound metals are no longer mobile within a geological time-scale. Applied biomineralisation uses microorganisms, which are isolated from a metal waste environment and are selected for their ability to rapidly catalyse neo-mineral development from dissolved or leachable metals. A typical waste environment will contain microbes that contribute to the mobilisation of metal contaminants as well as microbes that possess the potential for remineralising available metals. Selection and augmenting the correct combination of bacteria and eliminating the competing mineral degrading reactions are the key to applying biomineralisation as an in situ remediation process. Applied biomineralisation harnesses the microbesÆ ability to stabilise toxic soluble metals into non-mobile mineralassemblages. This paper will discuss and demonstrate the biomineralisation process through several case studies including the Summitville mine site in Colorado, the McCoy-Cove mine in Nevada, the Argonaut mine in California, and an historic lead site in Crooksville, Ohio.

Jan 1, 2004

Rare-earth permanent magnetic roll separators, pioneered by our group a few years ago, have distinctly different operation characteristics compared to prior art electromagnetic separators of various types. Many new applications for dry high-intensity (or better: high-force) magnetic separation have been developed in a short time period. It has also been found that the new generation of separators generally are more efficient with regards to removal of weakly magnetic contaminants in glass and ceramic raw materials with minimum loss of valuable product compared to induced magnetic roll (IMR) separators.The latest development is in the area of production of clean magnetic concentrates at high recoveries. It is likely that the PERMROLLR magnetic separator will replace cross-belt and lift-type magnetic separators as a result of this most recent advance.The paper will review the features of the PERMROLLR magnetic separator in comparison with other types of magnetic separators on the market and give examples on applications.

Jan 1, 1990

Ridgeway Gold Mine (Ridgeway) has a clear mission to maximise its cash flows in order to deliver shareholder value and is developing strategies to achieve this. Business process management using leading measures is core to this approach. Leading measures indicate potential outcomes ahead of time, allowing time to adapt and improve. Ridgeway is making strategy a central organisational agenda, creating a focus to æput first things firstÆ by controlling æleadingÆ activities and mobilising employees to act. Feedback using specific, leading measures gives employees the opportunity to proactively adapt their behaviour in order to deliver internal business outcomes that generate cash flows and shareholder value. This paper will outline RidgewayÆs business approach to track and control processes from resource to revenue, with a focus on delivering cash flows and shareholder value. Ridgeway is implementing a Balanced Scorecard approach (Kaplan and Norton, 1996). A total business focus is taken and leading measures are identified. Specific measures are used to score our success from the perspectives of learning and growth, internal business processes, customer and stakeholders, and finance. These measures and improvement plans are targeted at strategies to maintain our ælicence to operateÆ with our community stakeholders, produce accurate plans and forecasts, improve our operational effectiveness and grow our business.

Jan 1, 2002

THE power requirements of the Mount Lyell Mining and Railway Company at Queenstown, Tasmania, have, since the inception of smelting operations in June, 1,,896, been derived continuously from the extensive forests in the watershed of the Queen River, adjacent to -the works, the firewood being of good quality, mainly composed of myrtle or beech (Fagus Ounninghami), eucalypts, and manuka (Leptospermum ericoides).The country is very rugged and mountainous, indented by numerous ravines and gullies, and intersected by many creeks, which are subject to periodical floods, under the influence of a heavy and persistent rainfall. The areas so far exploited aggregate a total of about 42 sq. 'miles, and this denuded country gives promise of ultimately becoming very valuable pastoral ground for cattle-raising. The tonnage of wood yielded per acre varies from 40 to 100 tons on stack measurement of 80 cub. ft. per ton, 60 tons per acre being considered a good average yield. The gross amount of firewood handled during the past 13 years approximates 1,200,000 tons, the greater portion of which has been obtained by ordinary tramming methods. The company's main line of railway, 3-ft. 6-in. gauge, has served as a trunk line for all supplies derived from the Queen River valley, south of the reduction works, while the northern and western areas have been exploited by means of...

Jan 1, 1911