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By M. van de Vijfeijken

This paper will first give a short overview of the Copper Mountain project in British Columbia, which just has started commercial operation earlier this year. The grinding process with one 34' x 20' SAG mill and two 24' x 39.5' ball mills will be briefly discussed. All three mills are gear driven by a ring gear, dual pinion and two low speed synchronous motors. Copper Mountain has installed on all three mills, the new state-of-the art dual pinion mill drives. All the inherent operation and maintenance features of this drive technology will be discussed, as well as the advantage of having variable speed control also on the ball mills. The installation and commissioning of the mills and drives at Copper Mountain will be briefly reviewed. Finally the first field measurements on these low speed mill drives will be presented, with the main focus on the low mechanical stress impact of these mill drives on the pinion and ring gear, as well as the accuracy of the load sharing between the two motors.

Jan 1, 2012

By Fathi Habashi

Extraction by organic solvents is a chemical process in which metal species in the aqueous phase react with an organic reagent to form an organometallic com- plex, thus, the metal species leave the aqueous phase and enter the organic phase from which it can be stripped back in the aqueous phase to obtain a pure and a concentrated solution. The metal in the organic phase is not bound to carbon atoms as in organometallic compounds but to oxygen, nitrogen, sulphur, or hydrogen by a co-ordination (dative) bond (Habashi, 1999).Solvent extraction was used for the first time in hydrometallurgy in connec- tion with the special and urgent materials requirements of nuclear energy during World War II. A plant was constructed in the United States for the preparation of high-purity uranyl nitrate solution. In this plant, the yellow cake (a high-grade sodium or ammonium uranate) was dis- solved in HNO,, and uranium was selec- tively extracted by ether then stripped by water to give a concentrated solution of pure uranyl nitrate. This was gradually followed by developing methods for other high-priced metals such as plutonium, thorium, niobium, tantalum, zirconium, hafnium, boron, beryllium, and molybde num. The second step took place in the 1960s when solvent extraction was applied for the first time to extract a rela- tively cheap metal-copper. At present, solvent extraction technology is wide- spread, well accepted, and highly efficient. Solvent extraction had its origin in the discovery, by Christian Friedrich Bucholz (1770-1818) in 1805, that uranyl

Sep 1, 1999

By T. Bednarski, T. McCallum, L. Moya, L. Nsenga, B. Mbao

The accumulation of solids in solvent extraction (SX) circuits can cause problems with the physical and economic performance of the operation. These solids are responsible for the formation of crud, a solid stabilized emulsion containing organic, aqueous, air, and fine solid particles. The build-up of crud in SX settlers can limit SX operation throughput, require plant downtime, lead to higher organic losses, or result in higher aqueous in organic entrainment (all of which can have a significant, negative economic impact). Current practices for crud management are typically reactive. Crud is physically removed after it has been allowed to build to excessive levels in the circuit and processed mechanically using centrifuges or filtration. A new proactive solution has been developed to prevent crud formation and build-up. Low ppm dosage of an additive, ACORGA® CR60, into the pregnant leach solution (PLS) has resulted in reduced crud formation in pilot and commercial scale for a variety of PLS streams. This paper will review results from operations in North America and Africa, covering heap leach, concentrate leach, and agitated leach feeds. INTRODUCTION Crud formation and build-up in solvent extraction (SX) circuits has been a long time topic discussed and claimed to be crucial to the whole hydrometallurgical process (Liu, et al, 2006). Crud formation is present in all SX systems be it copper, uranium, zinc, etc., and Ritcey (1980) defined crud as a stabilized emulsion containing organic, aqueous, and fine solid particles. The ore type and feed composition is a major determining factor of crud formation and typically contains Si, Al, Fe, P, and sulfates (Ritcey, 1980). It typically builds at the interface between the organic and aqueous, but can also be observed as floating crud on the surface of the settler, or bottom crud, which is common to find in circuits treating agitated leach feeds such as in Africa. As crud formation has been unavoidable, many of the current crud management techniques are reactive, allowing crud to form and build in SX circuits. Once it does, it is removed and treated via different mechanical techniques, typically through some type of filtration or three-phase centrifuge, to remove the solids and recover the organic phase trapped within the emulsion (Ritcey, 1980). Automated pumping systems have also been designed and are frequently used in North American operations. The time and capital required to react to crud formation can be an overwhelming aspect to SX operation.

Jan 1, 2019

By J. K. Armstrong, C. Feyerabend

"As mines are constantly growing and expanding, so do the challenges for emergency response teams. They have to keep up with the pace set by current and future production techniques. Although mines have now reached depths of several kilometres and their dimensions and complexity are that of an entire city, mines rescue still must be able to reach the most remote areas within the mine in a swift and safe manner. The duration of breathing apparatus and physical human capabilities are limitations. Therefore, alternative methods have to be explored to extend the time under oxygen for mine rescue teams without putting additional stress on the team members. To address this global trend, Dräger, Goldcorp and PAUS have partnered to develop a mine rescue vehicle that allows mine rescue teams to travel for an extended period of time through a contaminated atmosphere without the use of breathing apparatus, thus extending the range of their mission. By applying currently available techniques, the safe expansion of mine production can be ensured, giving mine rescue teams the ability to respond to accidents in a safer and faster way. INTRODUCTION With the reduction of easily accessible natural resources, there is a global trend toward searching for higher ore grades underground and/or continually expanding mines underground to extend their lifetime. While in some areas this trend has just begun, in other countries mines are reaching depths or horizontal dimensions that pose extreme challenges (Codelco, 2016). These challenges include safety relevant topics, such as rock stability, heat and seismicity, but also more basic issues such as distances to the working face, which can become crucial considering the cost to develop a new shaft or decline. To overcome this, there is a growing interest in collaboration among various stakeholders to drive the development and support of deeper mines and tackle the complexity of underground mining. This is evidenced by the fact that several industry and research groups and networks have formed, e.g. the I2mine project in Europe and the Ultra-Deep Mining Network by the Centre for Excellence in Mining Innovation in Canada. Due to commodity pricing and the trend toward renewable energy, metal/non-metal mining will be the driving force behind this development."

Jan 1, 2019

By J. Clark

Erosion control during the mining cycle can be more effectively planned using Erosion and Sedimentation Control Plans (ESCPs). This raises the issue of who should develop an Erosion and Sedimentation Control Plan Guidance document (ESCPG) to standardize the content of ESCPs. A search for ESCPG documents in Canada revealed no examples for mine sites. In the U.S. there are a number of regulatory authorities who developed such documents for mine sites, including EPA. An ESCPG is expected to result in: (a) plans will be more standardized (b) more clarity and efficiency for those generating ESCPs; (c) assisting regulators tasked with reviewing/approving ESCPs; (d) providing guidance for the mine effluent permitting process relative to sediment control; (e) providing a basis for developing and including ESCPs in the Environmental Assessment (EA) phase and the mine economic assessment; (f) applying and optimizing ESCPs above the ?watersheds? of sediment ponds; (g) utilizing the ESCPG document for ?exploration? sites; (h) lowering the risk of adversely impacting water quality downstream of mining activities; (i) providing a methodology for determining the need for sedimentation pond(s) during the construction and production phases; and (j) providing a clear environmental sustainability message relative to sediment control if the mining industry takes the lead in developing an ESCPG. ESCPs will proactively create increased administrative (regulatory) efficiency in the EA and sub-EA reviews relative to erosion control and sediment release from mine sites. This also assists the new initiative in BC, One Project, One Process (OPOP) and synchronous permitting (a variation of concurrent permitting): as an example, enhanced erosion control planning at the EA phase then allows the synchronous permitting initiative to proceed efficiently, particularly for the mine permit (Ministry of Energy, Mines and Natural Gas) and effluent permit (Ministry of Environment). Approximately twenty more management plans (e.g. ARD/ML, explosive management, emergency response, hazardous waste, sediment pond operation, environmental effects, environmental sampling, etc.) may also be entered into the EA process to create increased efficiency, and then feed into the synchronous permitting effort. The BC OPOP initiative also adds support to the Canadian Federal ?One Project, One Review Process? approach. The ESCP and a sediment pond management plan will also address the Canadian Metal Mining Effluent Regulations requirement for all discharges from mine sites to meet a grab sample of 30 mg/L Total Suspended Solids.

Aug 1, 2013

By E. Gaucher, M. St-Amant

"Among the electromagnetic surveys performed by SOQUEM in the last three years, a certain number of the more instructive cases have been chosen to illustrate the theory of electromagnetism by field examples of: (a) The depth penetration of the TURAM as compared to the SLINGRAM (Ronka) method. (b) The limitations of the TURAM as compared to the SLINGRAM method when a conductor dips the wrong way, or when it is small in size. (c) The expression of a shallow-dipping conductor in a SLINGRAM survey. (d) The effect on the SLINGRAM survey of deep ditches or reef structures.(e) A comparison between the CRONE and the SLING-RAM method in the Abitibi clay belt, by means of field and model studies, indicating a usually better signal-to-noise ratio for the SLINGRAM method. From the above and from other experiments, different electromagnetic methods are now being used by SOQUEM, depending on field conditions."

Jan 1, 1970

By R. L. Eadie, J. L. Luo

The effect of plastic deformation on near-neutral pH stress corrosion cracking (SCC) also known as environmentally assisted cracking was studied by cracking rate measurements. All the tests were conducted in a synthetic near-neutral pH solution. The traditional potential drop tests using compact toughness (C-T) specimens with 2-3 mm long pre-cracks showed varying plastic deformation by rolling would increase the material's susceptibility to SCC. This was confirmed by cyclic loading tests using double notched flat tensile specimens with 200-300 µm long pre-cracks which gave the same results that the specimen with large scale plastic deformation by tensile loading had a relatively faster crack growth rate than that with only small scale plastic deformation.

Jan 1, 2005

By C. F. Harris

Following the initial development of the zinc-lead blast furnace, efforts have been directed both at increasing the scope of the process and increasing the cash return. The paper reviews the process developments which enable the process to smelt efficiently a range of material which encompasses high-grade zinc sulphide concentrates. mixed concentrates, Waelz oxide, zinc ashes and other materials blended to give a furnace feed ranging from 25 to 65% zinc and from 1 to 25% lead, with a copper-lead ratio exceeding 1 to 8. The paper also reviews the process developments which have enabled the capacity of a furnace and condenser system of standard size to be boosted from 30,000 to 80,000 tonnes/annum. The benefits achieved are used as a justification for continuation of the development of the zinc-lead blast furnace. Predictions are made of the benefits expected from further developments.

Jan 1, 1979

By I. Colquhoun

Current practice tends towards "integrity as an afterthought". That is, integrity is treated as an isolated aspect of operations and maintenance. In fact, this works quite well. But it would work so much better and with less uncertainty if integrity management measures were introduced at the design phase and addressed the entire life-cycle of the pipeline asset. The talk will address the measures and metrics that can be implemented on a new pipeline during design to optimize integrity and deliver a comprehensive operating manual and integrity management program for the pipeline system. This deliverable should describe the risks to be assessed and monitored, and the actions to be taken to control these risk adequately. Properly executed, integrity by design will provide a good working estimate of the life-cycle integrity management costs and maximize system reliability.

Jan 1, 2005

By M. C. Bétournay, J. E. Udd

"The legacy of abandoned mines in Canada creates issues that impact on both the health and safety of Canadians and the environment. Solutions to the problems of abandoned minesites require a detailed understanding of site conditions, the engineering solutions which may be relevant, and planning for effective use of the land. In this paper, the authors outline the basic thrusts that have been developed at CANMET to address this problem. These include: multiprovincial agreements to develop a national database; methods of site rendering; a ten-year research program to develop engineering approaches; the review of a large number of case studies; and outlining the associated risks. Examples of the applications of this research are provided in the areas of: municipal, provincial, and federal co-operative projects; site-specific applications; and international linkages."

Jan 1, 1997

By W. C. Whittaker

Introduction When one thinks of a coal stripping deposit, the picture that usually comes to mind is that of a more or less flat seam from two to twenty feet in thickness overlain by ten to fifty feet of overburden, in suitable ratio for economic operation. This is the usual type of stripping deposit and is quite a common occurrence in various parts of the prairie provinces. Rather unusual types of coal stripping deposits are being presently worked as open-cut mines by Sterling Collieries, Limited, and the Co al Valley Mining Company, Limited, at Miles 47 and 48 on the Alberta Coal Branch, some 150 miles south west of Edmonton. These deposits are of interest chiefly because they represent turned-up and greatly thickened sections of the Mynheer seam, and as such they present their own problems, peculiar to the commercial exploitation of a seam of this type. The area in which these deposits occur was originally owned by the Pacific Pass Collieries, whose operations, however, were confined to under-ground mining at Lovett, some eight miles to the southeast. It was not until l918 that the value of these deposits was realized, when the Company now known as Sterling Collieries, Limited, opened their pit at Mile 47. At the inception of the work, coal was loaded directly into the railway cars by men using wheelbarrows. In 1920, a tipple was built, after which the coal was loaded by steam shovel into mine cars, hauled by steam dinkeys, and loaded over the tipple into railway cars. In 1922, the Coal Valley Mining Company entered the field at Mile 48, with an entirely mechanical equipment, and at the present rime these two are the only stripping properties in Alberta using mechanical equipment both for the removal of overburden and the loading of the coal. These Companies have operated continuously since that time, and have to date mined and shipped 4,000,000 tons of coal, and moved some 5,255,000 cubic yards of stripping. The present annual coal output for the two mines is about 240,000 tons.

Jan 1, 1935

By D. F. Scott

"DEFINITION OF THE REGION AND ITS BOUNDARIESTHE REGION of Western Canada covered by this re-port lies between the Precambrian rocks of the Canadian Shield and the structurally deformed rocks of the eastern Cordillera, extending northward from the international border to the 60th parallel. It is some 487,000 square miles in area, with a total sedimentary fill of about 535,000 cubic miles0>. It includes parts of the prairie provinces of Manitoba, Saskatchewan and Alberta and the northeast corner of British Columbia and forms part of the geological region known as the Interior Platform, commonly referred to as the Western Canada Sedimentary Basin. The bedrock comprises carbonates and evaporites of Paleozoic age that lie on Precambrian crystalline rocks and are over-lain by a relatively thick blanket of Mesozoic and Tertiary elastic rocks. The nearly flat-lying bedrock, covered by a thick mantle of glacial drift, forms the Interior Plains physiographic province."

Jan 1, 1970

By G. P. van Greunen

"The rehabilitation of underground excavations has been undertaken as long as mining has existed. The conventional methods have proven to be dangerous, time consuming and expensive. During the construction of Styldrift Mine at Royal Bafokeng Platinum several vertical and horizontal excavations had to be rehabilitated. With a zero tolerance attitude towards working in unsafe conditions, together with a non-negotiable timeline to construct and ramp up the mine, the project team could not rehabilitate these excavations using conventional methods. This paper details the approach used to rehabilitate excavations using remote methods and how it was adapted to suit varying operating conditions and requirements - ensuring that no person ever entered an unsafe excavation before it was fully rehabilitated and safe. INTRODUCTION Styldrift Mine is an expansion project of the Royal Bafokeng Platinum group. It is located in South Africa in the North West Province some 10 km south of the Sun City resort (Figure 1). The mine consists of a twin shaft system (Main Shaft and Services Shaft). Capital construction of the shaft and associated infrastructure started in 2009 and is projected to be completed during 2020. The designed steady state production capacity of the shaft is 230 ktpm of Merensky ore. Production ramp-up commenced in 2017 with steady state production set to be achieved 36 months later in the fourth quarter 2020.Merensky Reef was intersected at a depth of 600 m below surface and the shaft design has a mean mining depth of 630 m. The project was approved for execution in 2008 on the basis of a suitable mine design and bankable feasibility study. One of the main excavations that required rehabilitation was an underground reef silo, Silo 4. It is a key piece of infrastructure on the critical path to allow steady state production at Styldrift Mine to be achieved. During construction excessive scaling within the silo along its 64m length necessitated urgent rehabilitation to be able to meet the ramp-up schedule. The criticality and urgency of these excavations prompted the project team to reduce the risk of failure while ensuring safe and cost-effective rehabilitation. This paper will focus on the rehabilitation of Silo 4 while capturing the essence of the learnings of all the excavations that were rehabilitated remotely."

Jan 1, 2019

By M. B. M. Monte, M. L. Torem, E. R. Pecanha, A. G. Merma

The recent literature has unveiled the potential use of microbial strains in mineral bioprocessing. This study presents the use of a Gram-positive bacterium (Bacillus subtilis) as bioreagent for hematite flotation. The bacterium presents the ability to modify the properties of mineral surface (electrophoretic mobility and hydrophobicity). It was studied the electrokinetic behavior of hematite particles, before and after the interaction with the bacterial cells. The results revealed a shift of the isoelectric point (IEP) of the hematite after interaction with bacterial cells, suggesting a chemical adsorption mechanism. Moreover, after bacterial conditioning, the zeta potential curve of hematite presented high values in the alkaline pH range. The hematite and the bacterial surfaces presented contact angle values around 27.4° and 41.0°, respectively. According to the results, the B. subtilis strain was capable of modifying the hematite surface, and after interaction the hematite surface presented a contact angle value around 46.0°. The flotation tests were carried out in a modified Hallimond tube. The experiments revealed a significant increase in hematite flotability using the Gram-positive strain as bioreagent. The tests pointed out a maximum recovery of hematite in the presence of 600 mg/L and pH 5. Therefore, the results from this study showed the potential use of the B. subtilis strain as a biocollector for hematite flotation, and its possible application in the mineral flotation industry.

Jan 1, 2016

By Denis Raymond, Yvon Trudeau

"Abstract-The Orion gold mine, located 7 km northeast of the town of Malartic, Quebec, was discovered in mid-1985. Underground exploration was undertaken in 1986Ieading to commercial production in 1988. The upper part of the orebody was exploited above the 125 m level and a total of 131 090 t at an average grade of 5.31 g/t gold were extracted.This paper describes the authors' current knowledge and interpretation of the geology, gold distribution, and structure of the Orion No. 8 ore zone deposit. The deposit is an epigenetic lode gold occurrence somewhat unique in that both quartz-vein type and pyritic type of gold ore occur side-by-side. It is located within the Marban-Norlartic Deformation Corridor (MNDC) formed during a first deformation stage (D1). The MNDC is a well-defined regional structural feature in the Val d'Or- Malartic mining camp. Primary gold mineralization is associated with the D1 event and is represented by pyritized , silicified and brecciated basaltic lavas enclosed by ultramafic flow units. The ore zone is concordant with the MNDC. Felsic intrusions are spatially related with the ore zone, but their role in the genesis of the ore has yet to be defined.A second deformation event (D2) resulted in local folding, a second schistosity (S2) and reverse faulting. Gold remobilization, the formation of the gold-bearing quartz breccia and the emplacement of the main quartz vein at the No . 8 zone deposit were associated with this event."

Jan 1, 1992

By D. Royston

In SAG mills fed with a variety of ore types, hard packing between the shell lifters can come and go depending on rock type and rock size distribution and the presence of a binder. Packing can appear in all sizes of SAG mills, and can be tenacious. High ball impact forces (depending on ball size) in larger mills may compact and encourage packing. Packing can have a negative impact on milling performance and a change in shell liner design may be required to remove it. However shell liner design changes need to be managed with care to ensure liner reliability. In smaller mills control of packing can extend shell plate wear-life and may help to maintain milling performance in fixed-speed mills through the liner wear-cycle.

Jan 1, 2012

By J. Shibata, K. Manabe, A. Fuji, N. Matsunaga, D. Murakami, Yamaguchi University, T. Suzuki

"Spent hydrodesulphurization (HDS) catalyst contains rare metals such as cobalt, nickel (Ni), molybdenum (Mo), and vanadium (V). The overall objective of this project is to develop a hydrometallurgical process that provides a degree of high recovery and selectivity of these rare metals from spent HDS catalyst. As a part of this project, this study focused on (i) development of a solvent extraction-precipitation stripping process for separation of Mo and V from solutions and (ii) optimization of grinding conditions of alkaline leaching residue for selective Ni sulfuric acid leaching against aluminum (Al). Experimental results showed that effective separation between Mo and V can be achieved by the two-stage process; solvent extraction of Mo and V with TOA (tri-n-octylamine) and precipitation stripping of V with ammonium salt at pH above 8.0. Regarding grinding conditions of alkaline leaching residue for selective Ni leaching against Al, it was found that Ni leaching efficiencies increased by providing higher grinding intensity, while the Al leaching efficiency increased and then decreased with increasing grinding intensity.INTRODUCTIONHydrodesulphurisation (HDS) catalysts account for about one third of the total worldwide catalyst consumption and are extensively used for sulphur removal in petroleum refineries (Zeng & Cheng, 2009). Fresh HDS catalysts generally contain molybdenum (Mo) and nickel (Ni) on an alumina carrier, but various elements included in the crude oil such as sulphur, carbon, silica, arsenic, cobalt, and vanadium (V) deactivates HDS catalysts during HDS reactions. As a result, spent HDS catalysts contain high concentration of rare metals. For example, regarding to Mo and V, it has been reported in the literature that the concentrations of Mo and V in the general spend HDS catalysts are generally 10-30% and 1-12%, respectively (Zeng & Cheng, 2009), which makes it economically viable to recover these rare metals (Biswas et al., 1986).Among a number of processes proposed for the recycling of rare metals from spent HDS catalysts, alkaline leaching is often used for selective Mo and V leaching (Zeng & Cheng, 2009). However, the process which provides a high degree of separation between Mo and V from a leaching solution had not been developed. Therefore, the first objective of this study was set to develop a solvent extraction-precipitation stripping process for the separation of Mo and V from solutions. More specifically, using artificial aqueous solutions of Mo and V, a series of experiments was performed to optimize the extraction pH, stripping agent, and the stripping pH."

Jan 1, 2016

"THE GOLD MINING REGION of Timmins - Val d'Or, astride the Ontario-Quebec border, has long suffered the effects of rising costs during the period when the U.S. price of gold was fixed at $35 per ounce. The federal government, through such assistance programs as that set up under the Emergency Gold Mining Assistance Act (E.G.M.A. ) in 1948, has subsidized the gold mining communities of Canada for a total of over $300 million to March 31, 1972. Of this, the Timmins - Val d'Or ""gold belt"" has received more than twothirds, almost $220 million. In spite of these continuous subsidies, only 12 gold mines are still producing in the Timmins - Val d'Or belt, whereas 71 mines have received subsidies for some period since 1948. The vital question is how the communities previously supported principally by the mining of gold will survive in the long run, as many of the older mines either are already depleted or are quickly becoming so. With the rising price of gold on the 'free market in recent months, prospects look a little brighter for the time being. Even with the increased official price of U.S. $38, which made the maximum government subsidized price about $48 per ounce, gold mines have not sold any gold to the government since January 1972 and some stopped doing so months before that. The populace of the region has not been enthusiastic about relocation nor about extensive retraining programs in the past and probably will not be in the future. So, when the remaining gold mines become depleted, the old problems of community depression will remain."

Jan 1, 1973

By Fiona Campbell

"Modern history is full of breakthroughs in technology, all striving to increase productivity and efficiency. What are the elements that should be taken into consideration in the design and implementation of modern automation systems in a control room? Both industry and international standards are now demanding that Human Factors be considered as part of the design of control rooms to maximize efficiency and minimize the potential of human error which can lead to downtime and a loss of profit as a result of interruptions in production. As the current workforce ages and the younger generation matures, this is also becoming a key element when planning a control room. New standards are helping to address some of these challenges that are facing the mining industry today. With an increased focus on the operator, an intelligent and ergonomic workspace can both mitigate risk and optimize production. Optimization is money. We will examine how to analyze and implement innovative control room planning to maximize mineral processing production and minimize risks that can impact overall production and profit.INTRODUCTIONIn this day and age, optimization of production in an industrial environment is becoming more and more of a challenge. With ever changing technology as well as other external factors, this can be especially daunting. There are several key elements that may not be immediately obvious when planning a control room design or renovation, most notably the role of the human in this environment. Fatigue, stress, distraction, reaction times and situational awareness are all critical in a 24/7 environment. With the growing need to include human factors when considering and designing an optimal work and production environment, it is becoming even more important to design a control room that can address as many of today’s challenges as possible.The standard definition of the word “optimization” is “an act, process or methodology of making something (as a design, system, or decision) as fully perfect, functional or effective as possible.” (www.merriam-webster.com). If we apply this to business, what it really means is finding the most cost effective way to achieve the highest level of performance while considering constraints, both external and internal, by maximizing the desired factors and minimizing undesired ones. Sometimes, however, we can get caught up in the day to day processes, without taking a moment to step back and objectively review what it is we need to achieve, and more importantly, the steps that can facilitate our success."

Jan 1, 2016

"One of the workhorses of the minerals industry is the autogenous grinding (AG) mill and its derivative the semi-autogenous (SAG) mill. These are relatively well understood, but not so Scrubbers. Scrubbers are mechanically of the same appearance/function, so what is the difference between an AG mill and a scrubber? When, or under what conditions should a scrubber be used and when should an AG mill be used? Can the processes within be mathematically modelled?In the past decades, the minerals industry has focused most of its attention on the modelling of unit processes such as cone crushers, HPGR’s, AG/SAG mills and ball mills within conventional processing circuits. Less attention has been placed on the modelling of scrubbers. This paper reviews the difference between scrubber and AG mill modelling, highlighting some of the similarities, with a view to confident comminution circuit designs.Engineering practitioners should be comfortable with these circuit designs and not shy away from considering AG mills for both small and large scale plants. AG mills can treat both harder or softer ore and scrubbers are for only softer ores. This paper differentiates scrubber and AG mill modelling in a similar way that overflow ball mills and grate discharge ball mills are analysed. Smaller scrubbers (600 kW) are suited to small scale soft ore (100-300 t/h) operations. Larger scrubbers up to 2,500 kW have the capability of very high throughput, in excess of 1,750 t/h with soft fine feed ore. AG mills are scalable up to 28 MW and are capable of treating harder ores at rates exceeding 2,000 to 4,500 t/h. Observations are that the specific energy requirements for the mill grinding duty is wide and varied. This is to a large degree the crux of the matter in sizing, as well as, differentiating, scrubbers from AG mills.INTRODUCTIONAG milling is a mature technology that has been used in minerals processing applications for more than 100 years. In the last 50 years, harder metalliferous ores have seen the introduction of steel balls to assist in the grinding/milling action. Tumbling mills used in such a configuration are called semiautogenous mills (SAG). The greater minerals industry is no newcomer to the use of fully autogenous (AG) mills. Perhaps scrubbers are. What is the difference? When should a scrubber be used versus an AG mill? How are they mathematically modelled?"

Jan 1, 2016