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By Whiten W. J

A simulation model was used to study the performance of various types of screen cloth on industrial vibrating screens. The model takes into account the effect of loading upon screen performance and predicts both themass flow rate and size distribution of the screen products.It was found that the use of the simulation model allowed the reconstruction of data for identical conditions and hence has simplified the analysis of the comparative performance of the screens. The dependence of performance upon operating conditions was found to vary markedly with screen cloth type.

Jan 1, 1977

By A F. Cooper

Otago Schist in the Mount Patriarch, High Burn and Cameron Creek areas of northwest Otago grades from textural grade IIA in the east to textural grade III in the west. The entire region is of the actinolite-pumpellyite metamorphic facies. Lithologies in the area are interbedded turbidite sequences comprising pelite and psammite together with pebble conglomerate, greenschist and metachert horizons. The mineral assemblage of the schist is typically quartz-albite-epidote-actinolite-pumpellyite-chlorite-stilpnomelane-calcite. A good foliation is well defined in the area and is predominantly parallel to bedding, except in hinges of mesoscopic isoclinal folds. The structure of the area appears to be defined by a large southwest plunging isoclinal fold defined by bedding with a steeply dipping axial planar foliation. Kink folding and dextral strike-slip faulting in the area postdates the ductile phase of deformation. Pods of rhodonite, rhodochrosite, spessartine garnet, coombsite, caryopilite, Mnstilpnomelane and Ni-Cu-Zn sulphides were found in concordant metachert layers in the Mount Patriarch area. Metachert was also found in float in the Cameron Creek area. Malachite occurrences relating to copper mineralisation were also noted in a green metachert horizon on the eastern flank of Mount Patriarch. The coombsite, in only the third observation worldwide, is the most Fe-rich variety reported.

Jan 1, 2003

The introduction of cement into underground backfilling at The Zinc Corporation, Limited and New Broken Hill Consolidated Limited mines to improve mining efficiencies gave rise to several major problems, the magnitude of which had not been anticipated. These problems were 1. A loss of recovery in the milling circuit due to the presence of cement 2. The presence of cement-rich slime layers on the surface of the fills 3. The introduction of a safety hazard due to the slippery nature of the surface of cemented fills 4. The deposition of cemented slimes on the levels and in underground sumps and dams. The loss of revenue due to decreased metal recoveries considerably offset the gains from increased stoping efficiencies and the use of cement was substantially reduced while, (a) the Metallurgical. Department attempted to identify the chemical nature of the problem and overcome it, and (b) the Mining Department investigated methods of reducing cement contamination of the ore stream. As a part of this investigation the Mining Department added polymeric flocculants to the cemented fill pulp. Testwork was carried out in the following steps 1. The available Alfloc polymers were screened to determine which was the most effective and what was its optimum dosage rate. 2. This polymer was used in the laboratory to determine the reduction of surface slime, clarity of water, and effects on strength and percolation of fill. 3. Fills were placed underground to substan- tiate the laboratory work. /+. The polymer was then added to all cemented fills going underground to study its effect over a long term. The use of flocculants not only improved the distribution of cement in the body of the fill, but also the distribution of the fines fraction of the filling material, practically eliminated slippery surfaces and improved the clarity of the drainage water. Flocculant is now added to all cemented fills and restrictions on the use of cement are gradually being lifted.

Jan 1, 1973

Routine, in-pit geological mapping of highwall at Central Queensland Coal Associates (C.O.C.A.) deep strip mines has proved too slow for the increasingly greater highwall lengths which require mapping. This realiz- ation has encouraged the search for faster mapping methods and after trial of ground photographic methods has resulted in the adoption of interpretive mapping off stereo cover, oblique -- aerial photography. This entails using a Cessna 182 light aircraft flying at its slowest speed, the aerial meth- od finally employed consisting of two Vinten, air reconnaissance cameras mounted in parallel and simultaneously taking both colour and black and white photographs of the mine high- wall. The respective 1:500 scale enlargements produced from the 70mm format films combine to present the sharpest resolution attainable under the field conditions pertaining and such information on weathered material as only colour photography can fully render. Total costs for the aerial photography method are estimated to be about the same as those for conventional in-pit mapping. Whilst total costs are comparable, geo- logist's time for mapping a 10 km. length is reduced to less than half that for in-pit mapping (for Stage 1, fully accurate mapping) and accuracy and detail are greatly improved. A permanent, accurate record of overburden

Jan 1, 1981

By J Lane, D J. Barker, B Pei

Queensland Alumina Limited (QAL) is the worldÆs largest producer of smelter grade alumina, located in Gladstone, Queensland, Australia. The plant employs evaporative cooling towers for waste heat rejection. Process water requirements include red mud residue disposal, steam venting to the atmosphere and Calcination feed moisture. Raw (untreated) water consumption in 2001 was 37 700 m3/d or 3.8 m3 per tonne of production. The Gladstone region experienced a water shortage in the period 2001 to 2003, resulting in progressive water restrictions. Industry operated under a ten per cent restriction from April 2002 and in November 2002 a 25 per cent restriction came in force. The maximum restriction level of 50 per cent was anticipated for the middle of 2003. Water restrictions of these magnitudes have the potential to result in significant production limitations, which would have major economic consequences for QALÆs owners, customers, suppliers and employees. Therefore it was imperative that measures be found to mitigate the impact of these restrictions. Furthermore, as one of the largest water users in the Gladstone region, QAL had an obligation to the community to minimise water usage as much as possible. A thorough analysis of water usage on site was conducted, focussing on all water streams leaving the plant. The philosophy used was that by minimising water outputs, the inputs would follow suit. Where possible, preference was given to solutions that provided lasting water savings. This occurs when the value of the water saving justifies the project cost, irrespective of water restrictions. By June 2002 an average water saving of 19 per cent was achieved, almost double the required saving. By end November 2002 further projects had increased the total water saving to 29 per cent, mainly through the re-use of GladstoneÆs municipal treated effluent as wash water. Further measures to reach the target of 50 per cent reduction were investigated. The evaporative cooling system was to be replaced with seawater cooling, using cooling towers to minimise the seawater pumping cost. Another benefit of this concept was the ability to dispose of the cooling tower bleed stream with the existing system for neutralised red mud disposal. This would avoid the need for an additional environmental outfall from the plant. In February 2003 the Gladstone region received over 500 mm of rain, which boosted water reserves to five years supply at forecast usage rates. This led to the lifting of all water restriction. As most of the implemented water savings measures are economically viable in the absence of water restrictions, raw water usage at QAL is still less than 75 per cent of pre-2002 levels.

Jan 1, 2003

By Segnit E. R

Results are reported of a study of the reactions occurringin the combustion of chaIcopyrite particles underconditions simulating those in the shaft of a flashsmelter.The reactions were studied using kinetic and mineralogicaltechniques. Reactions. rates above 500°C wererapid, most of the reaction taking place in less than 50ms. Final products were copper-iron ferrites with spineltype structures. Probable reaction mechanisms are discussed.

Jan 1, 1977

By A Nugraha, H Thanasekaran, K Tatetdagat

The Kanowna Belle gold mine is located in the Eastern Goldfields of Western Australia, approximately 18 km north-east of Kalgoorlie. The processing plant is designed to process 2 Mt/y and has the capability to treat both refractory and free milling ore from the Kanowna Belle and Kundana mining operations.The Kanowna Belle ore is refractory with the gold mineralisation occurring mostly as fine-grained inclusions in pyrite or as very fine-grained gold located in pyritic arsenic rich growth zones. The Kanowna Belle refractory process includes flotation, roasting of the flotation concentrate, and calcine leaching to extract the gold from the ore.Mineralogical analysis of feed and tailings streams from the flotation circuit have shown that the gold bearing minerals are well liberated and confirmed they are mainly associated with pyrite. Nearly 40% of the flotation circuit losses are in the -38 µm size fraction. To improve the flotation circuit recovery, the fine particle gold recovery was targeted. A Cavitation Tube column was selected for the site-based pilot test work program. This paper presents data generated from the on-site test work, and the benefits of the Cavitation Tube column to improve fine particle flotation.CITATION:Nugraha, A, Tatetdagat, K and Thanasekaran, H, 2018. Flotation circuit efficiency improvement at Northern Star Resources Limited’s Kanowna Belle gold mine, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 403–412 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

As world demand for various minerals increases the mining industry in its endeavour to satisfy this demand will, eventually,look to the extraction of orebodies which previously may have been uneconomical to mine. These orebodies may be of two types. Firstly, new low grade orebodies and secondly, remnant sections of previously mined orebodies. Some of the factors relative to remnant mining operations are discussed and the potent- ial of remnant mining in providing an important contribution to future world metal production is considered.

Jan 1, 1975

By J B. Collier, R M. Fraser, O Dahl, I M. Platten

Grade control is a process of maximising value and reducing risk, through the delivery of quality tonnes to the mill via the accurate definition of ore and waste. It essentially comprises data collection, integration and interpretation; local resource estimation; stope design; supervision of mining and stockpile management. The foundation of all grade control programs should be that of geological understanding led by high-quality mapping and sampling to drive appropriate estimation strategies and mining. Gold veins show various complex features relating to erratic grade distribution (nugget effect), variable geometry and internal architecture. These include variations in dip, strike and width, late-stage faulting/shearing effects and geometallurgy. Such variations generally require close geological understanding to ensure optimum grade, minimal dilution and maximum mining recovery. A well designed grade control program will prove to management and stakeholders that by applying geological knowledge, the mining process can be more efficient and cost effective. This paper reviews the issues of grade control in underground gold mines and focuses on integrated mapping and sampling through three case studies.

Jan 1, 2009

By J S. Laskowski

Froth flotation process requires the use of frothers. These important flotation agents are commonly characterised as either æselectiveÆ or æpowerfulÆ and are chosen following general guidelines and verification by laboratory and/or pilot plant tests. Fundamental properties of the flotation frothers have been extensively studied over the last few years. These studies have led to the development of standardised procedures to characterise frothers in terms of their ability to reduce bubble size and to increase foam stability. In this research project, the performance of five frothers in flotation of coal is evaluated and related to the fundamental properties of these agents. Since the recovery of water in the concentrate is closely related to the non-selective transport of solid particles by entrainment, the tested frothers are also assessed in terms of their ability to promote the transport of water towards the froth collection zone, both in absence and in presence of solids.

Jan 1, 2005

The Sishen iron-ore-mine produces 3 pro= ducts with size gradings of 25 to 8 mm, 11 to 5 mm and 5 to 0,2 mm and has a product capacity of 20 Mtpa. Ore is produced at an average Fe content of 66,2 % Fe for the two coarser pro= ducts and an average of 65,3 % Fe for the fine ore product. Three stage crushing is practised to re= duce the run-of-mine ore to -90 mm after which it is screened into five different size frac= tions of which four are heavy media beneficiated in static baths and cyclones and the fifth frac= tion discarded to slimes dams. A final three stage crushing and screening process is employed to produce the final three Products which are homogenized by means of blen=ding systems nrinr to despatch.

Jan 1, 1987

A model was developed of a CIL/CIP circuit for recovery of gold and silver. The model uses a simple two rate representation of the leaching kinetics. Parameters for the leaching kinetics may be simply obtained by sampling the feed to a circuit and the tailings from each tank and assaying the solids for both gold and silver to obtain the assay profiles of the solids down the tanks. The parameters in such a leaching model would be expected to be a function of the ore type, the grind, whether oxygen was used and the general chemical environment. These parameters are primary inputs to the model for any simulation. Standard power law relationships are used to express the practical equilibrium between the gold and silver cyanides adsorbed on the active carbon and the tenor of the solutions. The parameters for this may be derived from solution and carbon assays for the same set of samples. The model is constructed by writing a mass balance for gold and silver in and out of each tank in the train and for the circuit overall. Other inputs to a simulation are the feed rate of ore, per cent solids of the slurry in the tanks, gold and silver loadings of the input æbarrenÆ carbon and the rate of movement of carbon through the circuit counter-current to the slurry. With appropriate practical parameters the simulation is able to reproduce typical tank profiles.

Jan 1, 2004

By Konishi Y, Morioka Y, Okabe K

A part of the results of dissection survey of Chiba No.1 blast furnace, Kawasaki Steel Corporat- ion, is presented. Distributions of coke size and of slag and metal holdup are shown in the region of the dropping zone. A similar relation to the irri- gated packed bed is obtained. The distribution of coke size, coke temperature and liquid holdup are measured in and around the raceway. The shape of raceway in the horizontal and vertical sections indicates that each raceway worked individually. Liquid flow in the dropping zone and around the raceway on the basis of holdup measurements is Discussed.

Jan 1, 1981

By J H. Kyle

Cyanide is a significant cost in gold processing, as well as an environmentally sensitive issue. It has been suggested that precipitation of cyanide from leach liquors as copper-iron-cyanide compounds such as Cu2Fe(CN)6 may account for part of the total cyanide consumption. This may be especially true for ores that are rich in both copper and iron minerals. Ammonia addition has been shown to decrease the cyanide consumption by copper. Cu2Fe(CN)6.xNH3 precipitates have also been postulated to form during conventional cyanide detoxification processes, using oxidants such as SO2/air, with ammonia arising as a breakdown product from the oxidation of free cyanide. The present work has examined the conditions under which such precipitates may form, particularly in gold plant process and detoxification liquors. Ammonia and pH were found to have a large effect on the extent of precipitation. The compounds that were formed were found to comprise mainly Cu2Fe(CN)6.7H2O, as well as a range of NH3-bearing variants. The stabilities of the various precipitates are important from an environmental perspective. The long-term stability of copper ferrocyanide precipitates in tailings dams may be a problem under alkaline conditions and when some free cyanide is present, elevating the measured total cyanide in solution significantly. Case studies including data from actual plants are also considered, and the importance of these effects is reaffirmed from these results.

Jan 1, 2000

By Walraven F, Knott G. G

Using a typical small logging instrument (Neltronic KPD), a natural gamma reference section for part of the Brockman Iron Formation and part of the Mt. McRae Shale has been established in the Newman area. This is compared with the stratigraphic type section of Trendall and Blockley (1968). Folding and faulting are recognised using natural gamma logs. Because of the confidence with which stratigraphic horizons can be identified, less expenditure on diamond and percussion drilling is required to confirm stratigraphic position. Using natural gamma logs as stratigraphic control the apparent thinning of the Banded Iron Formation during iron enrichment is Demonstrated.

Jan 1, 1973

The traditional form of project financing for resource related projects has involved project financings structured with either recourse to the project sponsor(s) or commercial banks accepting the project's risks, usually after project completion, subject to, inter alia, the nature of the project, geographical location, quality of the projected cash flows and commodity price outlook. However, the concept of commodity-linked borrowings hasadded a new dimension for borrowing opportunities for resource-oriented projects and or companies.

Jan 1, 1985

By A R. Proudman, A H. Purvis

The Granites Gold Mine Callie gold deposit is located 550 km northwest of Alice Springs in the Tanami Desert. Gold mineralisation occurs due to a complex interplay of geological factors which include but are not limited to favourable lithology, structure, alteration and quartz veining. High-grade mineralisation, while pervasive under favourable conditions, is highly variable over short distances and is very nuggetty. In contrast, the lithology and geological structures that host the mineralisation are very continuous. Orebody modelling techniques have evolved over time because of a growing understanding of the mineralisation controls. Modelling issues such as sampling and assaying accuracy, modelling method, data density, gold population statistics, geological interpretation and domaining, grade boundary and calculation conditions, and model block size are constantly being reassessed in an effort to increase understanding of the mineralisation controls and modelling accuracy. The evolution of the modelling process in response to increasing data levels and a growing understanding of the mineralisation controls has resulted in changes to the perception of the orebody size and style. This has caused the choice of underground mining method to be revised several times and the process to final mining method selection to take longer than usual. In order to achieve the planned production start-up date of July 1998 the process has been allowed to progress in parallel with development of the underground mine. This paper describes the resource modelling and mining method selection process applied to the Callie underground mine and some of the issues which have contributed to its evolution. Some conclusions that are relevant to the efficient planning and development of new mining projects in general are presented.

Jan 1, 1998

By Lawson F

Pyrite concentrate and calcine from the Nanjing Lead-Zinc-Silver Mines, China, were leached with aqueous cyanide and thiourea solutions. More than half of the contained gold and silver was able to be extracted from the roaster calcines. The very fine dissemination of precious metal grains, high roasting temperature (850 - 900°C) and residual sulphur are believed responsible for the Iow extractions.A recovery of about 70 per cent for both silver and gold was able to be obtained with cyanide and with thiourea leachants when the pyrite was roasted in the laboratory at temperatures between 600 and 650°C.Thiourea, as an alternative leachant, has received much attention recently and a series of constant potential leaching tests was conducted.When the thiourea to formamidine disulphide mole ratio was about two, the precious metal extraction was greatest. In the Nanjing calcined material, this occurred at a potential of about 210 mV relative to a standard calomel electrode.

Jan 1, 1987

The Yabulu refinery of Queensland Nickel Pty Ltd located near Townsville now imports more than three million wet tonnes per year of nickel laterite ore from New Caledonia and Indonesia, making it the largest importer of any commodity in Australia. The project has illustrated that importing untreated bulk ore and re-exporting high value products makes good economic sense for the company and the nation. The economics of this exercise have been considerably enhanced in the past year by changing the project's principal product from nickel oxide sinter to refined high purity nickel metal. It is one of the few operations in the world where nickel ore is transformed to nickel metal at a single site. Several novel technological processes were developed at Yabulu and incorporated into the refinery to allow this product transition to occur. By utilising internally developed technology the new processes were installed at a capital cost of less than $10 million. It is unique for a large nickel producer to completely change the quality of its entire product range many years after the plant was constructed and considerable attention to marketing the new products has been required.

Jan 1, 1995

Total mechanisation in the Western district of New South Wales is quite a recent addition to productive methods in that State, for it was only in 1940 that the first colliery was equipped for this method of winning coal. Now almost all mines either are totally mechanised or are planning to get their coal by these means.This marked change in recent years is explained by the salient features of the industry's history. Collieries in New South Wales had generally been subjected to low selling prices forced on them by over-production and severe competition. Little money was available out of profits to purchase machinery, and returns on capital were so poor that inducement to invest money in the industry was nonexistent.The second world war brought price fixing at the already low prices. It was not until the post-war period that there has been any inducement to mechanise.Much credit for mechanisation can be given to the Joint Coal Board, a government body formed in 1948. Pursuing a broad plan for the rejuvenation of the industry, this Board, purchased large quantities of machinery for use in, mines under hire-purchase agreement. These agreements encouraged machine mining, and this fact, together with the ensuing production economies, has improved the financial position of the industry.The Board has also been instrumental in the granting of increases in the fixed price of coal, so that the industry has been given an even greater boost in the direction of mechanisation.

Jan 1, 1954