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By C. T. Bischoff

Introduction Air conditioning is a term which has come into common use only during our generation. By definition, it means the positive and accurate control of temperature, humidity, movement, purity, and component constituents of the atmosphere within an enclosure. Claiming such results for Noranda's ventilation system, or for that of any other large mine, at present would be an idle boast. However, we are working toward that end with considerable success. Modern underground ventilation at Noranda dates back about six years. The later development of air conditioning is in its fourth season, but still in the experimental stage. Various ingenious methods have been devised to cool mines which, because of climatic or geological conditions or depth, are excessively warm. A few installations have been made to warm intake air during the winter months where this is necessary. However, the method currently in use at Noranda is unique in that it accomplishes both ends by one process. This method utilizes the freezing and melting of ice to equalize year-round temperatures. Mining Methods While a discussion of mining methods at Noranda is not proposed in this paper, a brief summary may be in order. The Horne mine of Noranda Mines, Limited, has been developed by six shafts, four of which are now active. The most recent, an internal shaft, extends to 6,000 feet below surface, but all of the ore mined to date has come from above the 3,000-foot level. Figure 1 shows a model of principal ore bodies. The area mined is relatively small in plan, considering its vertical extent and the tonnage per vertical foot. Most of the ore lies within an ellipse about 600 by 1,000 feet. While this has certain advantages, the mining of such massive orebodies has presented many problems.

Jan 1, 1947

By S. S. Dimov, B. R. Hare

This paper describes two micro-beam analytical techniques(Dynamic SIMS and TOF-SIMS) which have become an intricate part of a comprehensive analytical approach for precious metal (PM) ore characterization and process mineralogy or deportment studies. The value of the D-SIMS technique is its capacity for accurate analysis in the sub ppm range along with the ability to produce high resolution elemental maps. The TOF-SIMS is significant for speciating and quantifying preg-robbed Au on the surface of carbonaceous material. In combination with traditional assays, the two techniques can provide invaluable information regarding the distribution of PMs within an ore along with providing insight into potential sources of PM loss in processing or where losses have occurred in process streams.

Jan 1, 2011

By Mathieu Dubé

Good mechanical strength of green iron ore pellets is required to avoid breakage and excessive deformation during their handling and further processing. However, green balls with good resistance to handling are often too plastic, which impacts the bed permeability in induration furnaces. Measurements of plasticity, bed void fraction and green ball sphericity as well as bed permeability were carried out on various samples of green iron ore pellets having different mechanical strength. Results show that bed void fraction, sphericity and permeability all depend, to some extent, upon green ball mechanical strength (plasticity). Understanding and controlling the mechanical strength of green iron ore pellets would then help to maximize both the productivity of the induration process as well as the quality of fired pellets through a more stable firing process. Results of research work carried out at COREM, with the objective of improving green ball characterization methods, are presented in this paper.

May 1, 2007

By Shen Zhengchang, Dong Ganguo, Chen Dong, Zhang Ming

"It is advantageous to process low grade ores with large scale flotation cells. Large-scale flotation cells have been enhanced with effective volume scale-up. In this paper, the latest and largest flotation cell with effective volume of 680 m3 in China is investigated. The hydrodynamics and flotation kinetics characteristics are conducted using CFD simulation. The similar circulating flow is formed compared to the previous BGRIMM (Beijing General Research Institute of Mining and Metallurgy) flotation cell and it is a suitable fluid dynamics environment. It is demonstrated that the flotation cell produces good gas dispersion and solid suspension. It is indicated that kinetic eddy dissipation plays a key role on collision kernel and collision probability profile. The higher collision probability profile appears at the impeller and stator regions aiding good metallurgical performances. The properties of the large-scale flotation cell are assessed using hydrodynamic numbers. The variation of hydrodynamic numbers such as the power number Np, the Froude number Fr, the air flow number Na, etc with flotation cell volumes show similar properties to previous flotation cells proven to be good in engineering applications. This research would aid structure optimization of the 680 m3 flotation cell.INTRODUCTIONFroth flotation is one of the mains method used in the mineral industry, which is used to process the most of metallic minerals. The proportion of low grade ores has increased with the minerals exploited around world. The increased capacity of concentrators demands large-scale flotation cells. Therefore, flotation equipment has seen a significant increase in size, for which large-scale flotation cells have prominent advantages in improving metallurgical performances, reducing area of plant blueprint printer, lowering the power consumption of the unit ore, decreasing labor cost and overall capital cost. Since the end of 1940’s, flotation cell sizes have continuously increased. To the end of 1990’s, flotation cells with the effective volume of 200 m3 were developed. In the last two decades, flotation cells have achieved a dramatic increase in size. In 2003, an industrial experiment on 257 m3 Smart Cell flotation cells was carried out in Minera Los-Pelambres, Chile. In 2007, the first 300 m3 Tank Cell flotation cell was designed and obtained industrial application in Macraes gold ore, New Zealand. And 320 m3 BGRIMM flotation cells are also in good operation in Toromocho Copper Mine, Peru and Wunugetushan Copper Mine, China. However, flotation cells are conventionally designed using empirically derived relations and geometric similarity. The continual scale-up of flotation cells is still a significant developing process. A 500 m3 Tank Cell was designed for the industrial experiment in Finland and a 620 m3 Tank Cell have also been completed the design. A 660 m3 Super Cell also was manufactured for the industrial experiment released in IMPC 2014. So, the flotation cells with volume exceeding 600 m3 become a pioneering research field for researchers worldwide."

Jan 1, 2016

By Ausenco Engineering Canada

"This paper demonstrates the selection of grinding circuit technology for a number of recent projects including discussion of the key drivers and the role of energy efficiency. Decreasing head grades combined with a strong and sustained increase in operating costs has forced miners to examine increased project size, increased equipment capacity and efficiency improvements in order to reduce their unit operating costs and improve overall project economics. Comminution energy consumption, safety and capital cost considerations play a critical role in the success of projects. This paper presents some key guidelines for a successful and cost effective comminution circuit design and includes a case study on three projects, outlining the issues and the drivers which led to the ultimate circuit selection and the critical role that energy efficiency played.INTRODUCTIONComminution circuits for minerals processing are selected based on their suitability and efficiency in reducing run-of-mine ore to the desired feed size for the downstream process. The input material (ore) properties and downstream process requirements are the key determinants and there are standard approaches for each circumstance.The minerals processing industry has been a fast adaptor of efficiency improvements based on increasing capacity of equipment (e.g. trucks, crushers, mills, pumps) but less successful in adapting radically new technologies that disrupt incumbent flowsheets or processes.The installed power of grinding mills has increased linearly over the past 25 years (Meka & Lane, 2010) and pumps and classification equipment have kept pace. The autogenous grinding (AG) and semiautogenous grinding (SAG) mills displaced stage crushing as a dominant method of coarse rock breakage in many applications causing crusher manufactures to increase the capacity of cone crushers to meet the competitive demand.Examples of new comminution technology in the 20th and 21st centuries are the development and adoption of cyclone classification in the 1940s (Newtech, 2016), AG milling in the late 1950s, vertical grinding mills in the 1980s, high pressure grinding rolls (HPGRs) also in the 1980s and ultrafine milling technology in the 1990s (Meka & Lane, 2010)."

Jan 1, 2016

By J. L. Feng, F. Zhang, S. K. Hu

"Cracking is one of the most serious damages in tunnel linings, which is often observed by in-situ inspection to tunnel engineering. It is difficult to better characterise for the deformations from continua to discontinua by the traditional continuum mechanics due to emerging of crack initiation, crack propagation, and coalescence, at several scales. In this paper, the process of failure that was from micro damage to macro crack in concrete tunnel linings under experimental load conditions, was quantitatively simulated by the combined finite-discrete element method (FDEM). Comparison of the simulating results with that obtained by the full-scale test of concrete lining under different loading conditions in the literature was respectively good agreed and shows that such FDEM technique is appropriate to model the continuousdiscontinuous problems. The present study indicates that the FDEM technique could be benefit to quantitatively evaluate the stability and damage level of tunnel lining system. INTRODUCTIONMost damage to tunnel linings is caused during the construction phase, which can emerge in a form of single macro cracks or even large-scale spalling. The cause of such damage is mostly the occurrence of, either impermissibly large contact stresses resulting from high thrust loads combined with production and installation tolerances in the segments resulting in a geometrical lack of fit (Maidl et al., 2012; Transportation Research Board, Basic Research and Emerging Technologies Related to Concrete Committee, 2006), or unallowable tensile/shear stresses appearing in the tunnel linings under complicated loading conditions (Ansell, 2010). Such a macro failure phenomenon may also be regarded to as a result of growth, coalescence, initiation of microcracks in tunnel linings due to the complicated loading action, and even potentially lead to an instability or collapse of the local or entire tunnel system. Much work has been devoted to investigate for the characters of micro and macro cracks, the influence factors of damage patterns, the settlement of a tunnel, the width, length and density of lining cracks, especially from classifiedly and qualitatively (Wang, 2010; Huang et al., 2013). However, the safety evaluation of tunnel is definitely required to not only inspect in situ, but further also quantify computing and analyzing for tunnel lining systems, so as to provide a global viewpoint of process of the tunnel deformation, which aims to help for subsequent decisions, e.g. controlling traffic flow or immediately repairing task. Additionally, the design of lining thickness and its structural analysis that is mostly determined by previous experience and similar construction examples is also needed to be improved."

Jan 1, 2015

By Roger St. C. Smart, Paul Weber, Joan E. Thomas, William M. Skinner, Warwick Stewart, Stuart Miller

For mine sites affected by acid rock drainage (ARD) or with a potential future ARD issue, the prime consideration is not only the classification of different waste rock as potentially acid forming or non acid forming but also the peak acid (and metal) release rates and expected ARD duration during which effective ARD management and acid neutralisation capacity (ANC) are required. Methods for assessment of this ANC (e.g., Sobek tests) are already available but can be unreliable in ARD containing significant proportions of framboidal pyrite or iron carbonates. The measurement of negative ANC values and the release of S to solution showed that significant sulfide oxidation may occur prior to and during testing in samples containing reactive (particularly framboidal) pyrite resulting in serious underestimation of the original ANC. A simple methodology with dissolution in Ar-purged water before ANC testing, removing ferrous salts, and sulfate assay after ANC testing corrects these effects. Results also showed that a significant lag period (up to 432 h) may be needed for complete hydrolysis of Fe associated with the standard Sobek ANC testing of, for instance, siderite. Hence, the ANC of iron carbonates is usually significantly overestimated. By filtering and the addition of H202 until there was no subsequent pH drop (due to Fe hydrolysis reactions), followed by back titration to pH 7.0, the ANC for siderite was similar to the ANC determined after 432 h lag by the Modified Sobek ANC test and to the mineralogical carbonate ANCcarb determined by calculation based on electron probe micro-analysis. A chemical ANC calculation, based on neutralising cations released to solution, has provided a method to quantify the short-term ANC of carbonates and silicates in simple mixed mineral assemblages and waste rock samples. Results showed that silicate ANC can be more important in short-term neutralisation than carbonate ANC in low carbonate samples. In the longer-term, decreasing sulfate and metal loads with increasing pH values suggests that eventually sulfide acidity generation rates will match the longer-term inherent acid neutralisation rates of the sample derived from silicates. A kinetic ANC measurement for silicates, after steady state dissolution is reached, that indicates the number of hydrogen ions neutralised/m2/yr has been developed. These values can be used in estimates of the net acid production profile from wastes with low (and decreasing) pyrite content after the short-term ANC is exhausted.

Jan 1, 2004

By E. Hardwick, K. C. Sole, Y. Jurrius

"The Luilu cobalt plant at Kolwezi, Democratic Republic of Congo, has been operating since the late 1950s, using a conventional precipitation flowsheet for removal of impurities from the cobalt process stream. Most impurities are, however, incompletely removed using this technology. Copper and zinc, both of which quantitatively deposit at the cathode in the cobalt electrowinning process, are two of the main impurities contaminating the cobalt metal product. Ion exchange offers a modern approach to removing these impurities from the cobalt advance electrolyte.Following a laboratory testwork programme to identify a suitable ion-exchange system, an on-site pilot-plant trial, treating 1500 to 3000 L/d of electrolyte, was operated for a period of six weeks to optimise the operating conditions and to determine full-scale design criteria. Copper removal was carried out using a fixed-bed lead-polish configuration with the Lanxess iminodiacetic acid resin, TP 207. Zinc removal was subsequently carried out in a similar configuration using the Lanxess aminophosphonic acid resin, TP 260. The optimised system proved capable of removing both copper and zinc from 20 to 30 mg/L to <1 mg/L from plant electrolyte containing ~20 g/L Co. Selective elution allows co-loaded cobalt to be returned to the main circuit and value to be obtained for the copper impurity. The process shows operational and economic advantages over the traditional flowsheet. Full-scale implementation of the developed process is in progress and some design considerations are discussed."

Jan 1, 2014

By J. G. Martin, J. C. Campbell

THE VICTORIA JUNCTION 31,4-million-ton coal preparation complex went into operation in October 1976."' It is designed to produce a metallurgical coking coal by lowering the sulphur and ash content of the raw coal using a heavy-media cycloning process to treat deslimed crushed coal, with scavenging of fine coal by flotation from the primary minus-28-mesh screen product. A secondary H-M cyclone scavenges a thermal-grade coal from the primary H-M cyclone tailing.

Jan 1, 1985

By Omkar N. S. Beruar

Extraction of sill pillars has always been problematic because of high risk of seismicity and rockburst. Depending on a number of factors, a sill pillar can undergo different failure modes and cause problems in the mine. Of these, sudden and uncontrolled failure of part(s) of the pillar leading to highenergy seismic events and rockbursts is a main concern because it is not possible to predict the location and time of a rockburst apart from its potential to cause extensive damage to the mine structures. To date, a comprehensive technique for sill pillar design and recovery does not exist. Conventional methods of pillar design, such as the pillar stability graph method, are utilized to design stiff sill pillars. In these design approaches, the post-peak response of the pillar-rock system is not considered. This is in part due to a lack of clear and comprehensive understanding of the post-peak behaviour and failure mechanism of sill pillars. In general, the strength of a rockmass is described using a failure criterion. When stresses reach the strength of the rockmass, the rockmass does not necessarily become unstable and knowledge of the loads alone is not enough to assess the instability conditions accurately. In fact, it is not possible to predict instability of rockmass based on the strength/stress ratio alone because instability depends not only on this ratio but also on the loading condition and loading system characteristics. The loading system can dictate whether the sill pillar will go through a stable or unstable failure process. This paper examines the influence of various parameters such as the pillar width to height ratio, the extraction rate, and placement of backfill on the Loading System Stiffness (LSS) and the Pillar Stiffness (PSS). The ultimate goal is to design yielding sill pillars that would yield in a stable manner and will reduce the risk of pillar rockburst. Plane strain finite element analysis is conducted using the generalized Hoek-Brown failure criterion with elastic-brittle-plastic parameters. Examples are given to demonstrate how to calculate these stiffness values and assess the stability condition of sill pillars. It is found that increasing the rate of extraction increases the likelihood of unstable yielding of the pillar as has been found in other studies. Placement of backfill in a timely fashion in the stopes above and below the sill pillars increases the stiffness of the loading system. This indicates that backfilling of stopes while creating the sill pillar increases the likelihood of stable yielding of the sill pillar.

Aug 1, 2013

By D. F. VanDine

The phases of a typical exploration program for sand and gravel resources include: (1) collection and assessment of existing information; (2) air photo interpretation and remote sensing; (3) ground investigation and mapping; (4) sampling and testing; and (5) data storage, retrieval, analysis and presentation. Depending on the purpose, time frame and funding available for the study, these phases, and the various techniques used within each phase, will vary. Once a sand and gravel deposit has been located, defined in size and quality, and found to be suitable for a given purpose, it can then be classified as a granular resource.

Jan 1, 1984

By C. E. Ells

Current knowledge of the behaviour of inert gases in metals is reviewed, with particular emphasis given to the phenomenon of the growth of gas-filled bubbles.

Jan 1, 1960

By J. Jung, W. Keller, N. Rohn

In hydrometallurgical minerals processing slurries are often processed at very small grind sizes and high solids concentrations. This normally results in flow anomalies of such slurries. Due to flow limits or yield stress the slurry tends to stagnate close to the vessel bottom, the walls and at any internals. The main mixing task therefore generally is not suspending of the solids but the homogeneous blending of the entire vessel volume. If not considered during the agitator design only a fraction of the vessel contents will be mixed. Therefore the knowledge of the slurry rheology as well as the variations in process parameters is vital to design e.g. storage or surge tanks. The integral mixing solution considers the motor power, the choice of the impeller type and number, the impeller diameter as well as the design of the baffles and feed and discharge positions.

Jan 1, 2014

By P. A. Crane, N. Shirley, Aung Moe, H. M. Nicholson, D. Kan

Kazakhstan’s first commercial copper-leach solvent extraction-electrowinning plant, Central Asia Metals’ Kounrad project, was commissioned in April 2012. Exploiting low grade waste stockpiles produced during Soviet era open pit mining, a 10,000 tpa copper cathode plant was designed, constructed and commissioned within 18 months. Overcoming initial challenges with a workforce unfamiliar with the technology and with extensive periods of sub-zero conditions during winter the project has consistently met targets and produced high quality copper cathodes at cash costs of less than US$1/lb. Challenges encountered during the first two years of operation are described and future plans briefly discussed.

Jan 1, 2014

By W. J. Cherones

This paper describes the history of the development and application of the electric mining shovel in open-pit mining, dea1ing particularly with far-reaching advancements in three primary areas: metallurgy, mechanical design and electrical systems. Hoist drives and crowd drives, including the Magnetorque and Electrotorque systems, and the integral propel drive are given close attention.

Jan 1, 1972

By S. Mathieu, R. Mennillod-Blondin, P. Cousin, N. Valle, H. Bouzahzah, P. Marion

The gold deposit of the Lapa mine has a complex mineralogical gold state with coarse and fine native gold, aurostibite and submicroscopic gold within arsenopyrite. A specific mineralogical characterization of the refractory fraction was conducted combining various techniques such as optical microscopy, electron microscopy, electron microprobe and secondary ion mass spectrometry. In parallel, the mineral processing behaviour and the recovery of the refractory gold were studied by pressure oxidation and cyanide leaching. This paper presents the mineralogical methodology developed to characterize the refractory gold distribution within arsenopyrite. These results are presented and interpreted in order to plot gold recovery versus sulphide oxidation. The comparison of the metallurgical behaviour yields predicted from the mineralogical data and the one calculated from leaching tests shows a good agreement and allows mineralogical explanations of the gold metallurgical behaviour.

Jan 1, 2011

By Arthur L. de Carle

"IntroductionThe Key Lake uranium-nickel deposits are located within a Mineral Lease centred at latitude 57 ° 12' north and longitude 105 °39' west along the southeastern rim of the Athabasca sedimentary basin in northern Saskatchewan, approximately 240 km north of La Ronge (Fig. 1). Access is provided by an allweather provincial highway from Pinchousc, situated about 200 km to the south, and a private airstrip maintained at the mincsitc.These deposits have been developed by Key Lake Mining Corporation on behalf of the Saskatchewan Uranium Joint Venture. Participants in the joint venture include Saskatchewan Mining Development Corporation (50%), Urancrz Exploration and Mining Limited (33 1/3 %) and Eldor Resources Limited (16 2/3 %).Considerable geological work has been conducted on the Key Lake orebodies and reported in summary papers published by Dahlkamp and Thn, (1977), Dahlkamp, (1978), Gatzweiler eta/., (1979) and Kirchner el a/. , (1980). However, intensive geological research is ongoing, particularly since many problems regarding ore genesis and controls remain unresolved . Exploration History and DevelopmentThe events (Gatzweiler eta/., 1980) which led to the discovery of the Key Lake ore bodies began in the summer of 1971 by following up on the reports of airborne radiometric anomalies and anomalous radon values in the Zimmer Lake water situated approximately 5 km to 6 km to the southwest. This work succeeded in locating a few high-grade uranium and nickel-bearing boulders associated with esker material. An integrated program, consisting of various geochemical and geophysical surveys along with diamond drilling, culminated in the discovery of the Gaertner orebody during July 1975. Subsequent fence drilling across the strike extensions of this ore structure located the Deilmann deposit, approximately I km to the northeast, in June 1976"

Jan 1, 1986

By Denis Racicot

"L'Abitibi québécois a produit essentiellement de l’or, du cuivre, du zinc et de I' argent, ainsi que de faibles quantités de nickel, de plomb, de molybdène, de bismuth, de lithium, de fer et d’amiante. Depuis l’ouverture de la mine Horne en 1927, cent-cinquante mines ont contribué à la production de 1 420 tonnes d’or de 4,1 millions de tonnes de cuivre et de 4,7 millions de tonnes de zinc. Les productions minières annuelles ont été d'importance variable: des records de production ont été établis en 1955 pour I' or avec 35 tonnes et, vers 1965, pour le cuivre, le zinc et la quantile globale de minerai extrait avec respectivement 130,000, 275 000 et 13 millions de tonnes. Deux dépressions généralisées ont eu lieu, l’une vers 1946 et l'autre, a lafin des années soixante-dix. Des ralentissements de la production ont été observes pour le cuivre en 1953 et le zinc en 1959. Depuis le debut des années quatre-vingt. I' or et, de façon plus irreguliere, le zinc sont en progression, landis que le cuivre, malgre une hausse en 1983. pour suit son dec/in.La teneur de récupération des mines d’or est demeurée régulière et n’a subi qu’une faible diminution au cours des quarante dernières années. Célie du cuivre a diminué d'environ 50% dans la même période, landis que celle du zinc a subi d’import antes variations, aussi bien positives que négatives. Près des trois quarts des mines d'or ont une durée de vie inférieure à 12 ans et la distribution des tonnages de minerai extrait montre un maximum pour la classe de 100 000 à 1 million de tonnes. Du cote des mines de métaux de base, la durée de vie est plus étalée et les volumes de minerai ont une occurrence maximale dans la classe de 1 à 10 millions de tonnes.Concernant la distribution géographique de la production minière dans l'Abitibi québécois, le camp minier de Rouyn-Noranda vient en tête pour l’extraction de minerai et la production d’or et de cuivre. L’est sui vi par le camp de Val d'Or pour le minerai et l’or, landis que le camp de Chapais-Chibougamau occupe la deuxième place pour le cuivre avec une production équivalence a 60% de celle de Rouyn-Noranda. Le camp de Cadillac-Malartic suit de tres pres celui de Val d'Or pour ce qui est de I' or. Finalement, dans le casdu zinc, le camp minier de Joutel-Matagami domine largement avec une production qui a connu un développement accélère depuis 1963. Une analyse pré liminaire de ces données indique qu' i/ subsiste unpotentiel encore élevé de production d'or, décuivre et de zinc dans I' Abitibi québécois. ABSTRACTThe Quebec portion of the Abitibi belt has essentially produced gold, copper, zinc and silver, as well as some small quantities of nickel, lead, molybdenum, bismuth, lithium, iron and asbestos. Since the opening of the Horne mine in 1927, one hundred and fifty mines have produced 1420 tons of gold, 4,1 millions tons of copper and4,7 millions tons of zinc. Annual mine production has fluctuated: production records were established in 1955 for gold with 35 tons, and around 1965 for all extracted ore copper and zinc with respectively 13 millions, 130 000 and 275 000 tons. Two main recessions have occurred, the first around 1946 and the second during the late seventies. Cut backs in copper and zinc production occurred in 1953 and1959. Since the beginning of the eighties, gold production and to a lesser extent zinc production have been in progression. Except for a small jump in 1983, copper production is still declining.The average recuperation grade of gold mines has been quite steady and has only slightly diminished in the past forty years. The average copper recuperation grade was halved during the same time interval. For zinc there have been important ups and downs. At least three quarters of gold mines have an average lifespan of 12 years the tonnage distribution shows a peak in the 100 000 to 1 million tons class. Base metals mines show a more widespread life expectancy and have a tonnage peak in the 1 to 10 millions tons range"

Jan 1, 1990

By T. T. Ni

FOR MORE THAN 200 years, the Kochiu district of Yunnan province has been, and it still is, the hub of China&apos;s tin industry. The district produces annually from 80 to 90 per cent of that country&apos;s out-put of tin, which averages about 9,300 tons a year and places China fifth among the tin producing nations of the world. The tin ore reserves of the country are estimated (1) at 1,873,370 metric tons, of which 1,500,000 tons are in the Kochiu district. The mill of the Yunnan Consolidated Tin Corporation, described in this paper, is the only one of its kind in China. MINING AND SMELTING There are only two tin mines in the Kochiu district operating with modern equipment -the Hsin-Chang and the Lao-Chang, both owned by the Yunnan Consolidated Tin Corporation, a government company. The Hsin-Chang mine has four working levels with cross-cuts 6 ft. by 6 ft. and is equipped with steel mine cars and trucks to haul the ore. The ore is hoisted to surface in a three-compartment shaft and transferred to the mill by a 4-kilometer aerial tram. The Lao-Chang mine has two circular shafts 656 feet apart, each equipped with two cages. Haulage-ways 1,600 meters and 1,000 meters long, respectively, have been driven to the southwest from these shafts and are connected by three cross-cuts.

Jan 1, 1951

By van der Meer. F. P.

High Pressure Grinding Roll (?HPGR?) technology is applied in a broadening range of minerals processing applications for relatively wet or moist materials. HPGR grinding of dry material or involving drying and air classification is more common, for example in cement manufacturing. A number of minerals processing plants are also operating with dry material, either due to process reasons, such as considerations of preceding or subsequent process stages, or as dictated by local conditions of arid areas and scarcity of water. The present world-wide expectation of decreasing availability of water supply urges us to look for alternatives that minimize water consumption. Recently established and envisaged future HPGR applications with dry ores have indicated that the technology of dry crushing and classification as practiced in cement and limestone grinding can be applied in minerals processing. Moreover, dry technology could very well be applied for generating a final fine product at sizes near or below 100 microns, as may be required for beneficiation by, for instance, flotation, magnetic separation or tank leaching. Dry HPGR grinding requires special attention in maintaining suitable process economics, when considering power input in grinding, drying and classification. In some cases, HPGR capacity and roll surface wear life may be negatively affected by a lack of moisture in the feed. This publication summarizes some of the features of, and experiences in dry HPGR applications. This includes design aspects of the classification system and discussion of the wear protection of the roll surfaces. The paper also includes examples of operational experiences of dry practices in minerals processing and cement plants.

Jan 1, 2012