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By W. Griffith

"While oxalic acid precipitation practices are commonly applied on purified rare earth elements (REEs) pregnant leaching solutions (PLS), few efforts have been reported using oxalic acid (OXA) to recover REEs directly from untreated PLS. High oxalic acid demand is the most significant issue in all these direct oxalic precipitation (DOP) practices. Preliminary research on DOP of REE from a dilute PLS originating from an acid bake followed by water leaching was conducted. At 75°C, the oxalic acid demand was between 12 and 18 times the stoichiometric requirement for complete REE precipitation. Conducting DOP at 25°C had superior REE recovery but the product purity and filterability declined. Between 75°C and 100°C, REE recovery increased with increasing temperature. When sodium hydroxide was used to adjust the pH during DOP, in the range of 0.5 to 1.5, higher pH benefited REE recovery. Using ammonium hydroxide in place of sodium hydroxide, the REE recovery was reduced by close to 5%. Sodium chloride addition to the PLS was also investigated and the results showed that at both 75°C and 25°C, the REE recovery was enhanced substantially. At 25°C, when the oxalic acid addition was controlled at 4.7 times the stoichiometric requirement, the overall REE recovery reached 95% with the addition of 240 g/L NaCl. Other reagents such as KCl, NH4Cl also showed significant enhanced REE recovery at the same oxalic acid addition. The addition of sodium sulphate appeared to largely enhance the precipitation of LREE but inhibited the formation of HREE oxalate. All results indicate the formation of rare earth double salts may play an important role in REE DOP sulphate media.INTRODUCTIONThe conventional routes for recovering rare earth elements (REEs) from a sulphuric acid pregnant leaching solution (PLS) involves an initial purification step for removal of iron, aluminium for example by precipitation through neutralization, followed by precipitation of REEs as hydroxide, oxalate or carbonate salts, or by bulk solvent extraction for REE recovery (Xia, 2013). Another route was used by Bayan Obo in their historical flowsheet, where the PLS was first subjected to double sulphate precipitation, then the remaining REEs, mostly heavy rare earth elements (HREE), were recovered by oxalate precipitation (Li, 2011)."

Jan 1, 2016

By G. Fuentes, J. Viñals

"The nature and basic kinetics of the hydrothermal reactions of bornite, covellite pyrite and enargite with copper sulfate solutions were investigated, as a previous study on the behavior of the bulk Chilean copper concentrates. The reaction of bornite produced digenite at 160 °C and djurleite above this temperature. Covellite was transformed to digenite at < 200 °C and to chalcocite (Q and M) at > 200 °C. The pyrite reaction was significant at > 200 °C and extensive at 240 °C, enargite reacts only above 240°C and produces digenite. The hydrothermal treatment of Chilean Codelco-type copper concentrates with hydrothermal reactions was similar to those obtained from pure mineral samples.INTRODUCTIONStudies on the hydrothermal enrichment of chalcopyrite concentrates were begun by MacGauley and Roberts (1951), Roberts et al. (1953) and MacGauley and Schaufelberger (1956). In the 1970's these processes were reexamined by McKay et al. (1972), and Johnson and Coltrinari (1976), but it not was until the 1990s when the kinetics, mechanisms and full engineering aspects were studied by Barlett, (1992), Jang and Wadsworth, (1994) and Peterson and Wadsworth (1994). The main objectives were to solve some important problems in the copper pyrometallurgy: The increase of the smelting capacity, the reduction of the iron slag – and associated copper losses – as well as the reduction of sulfur emissions. The present rise in copper demand and price implies the production and subsequent treatment of very impure concentrates. Thus, a significant increase of environmental problems can be expected in the copper pyrometallurgy. The previous purification of concentrates can reduce the processing of wastes containing hazardous heavy metals in the copper refineries and the hydrothermal treatment can be an alternative which combines both enrichment and purification. On the other hand, Chuquicamatatype concentrates (Viñals et al., 2004a) contains digenite (Cu1.8S), pyrite (FeS2), chalcopyrite(CuFeS2), b ornite (Cu5FeS4), covellite (CuS) and sphalerite (ZnS) as the main mineral components, with minor amounts of enargite (Cu3AsS4), galena (PbS) and molybdenite (MoS2)."

Jan 1, 2012

By Ian Ewart, Trevor Bergfeldt, Gourab Satapathy, Ajay Patel

"Conventional electrowinning (EW) of nickel from sulfate electrolytes is complicated by several factors including the requirement for a diaphragm cell to separate the anolyte and catholyte and the need to minimize nickel mist emissions. Developed and commercialized by emewCorporation, this novel process electrowins high purity nickel cathode (99.5%) from copper refinery bleed streams using the proprietary emew vortex EW technology. The emew nickel process incorporates high flow rate in an enclosed cylindrical EW cell operating at high current densities that overcomes the challenges of conventional nickel EW and completely eliminates the risk of nickel mist emissions. The tubular cathodes are easily harvested and mitigate the effect of plating stresses inherent in nickel EW. The present paper describes the emew nickel process and its most recent application to copper refinery bleed streams at full-scale.INTRODUCTION To meet the stringent demand of customers, nickel producers are giving prime importance to production of high purity nickel cathodes. The major challenge for refineries is to improve cathode quality and appearance despite fluctuating electrolyte impurity levels. The basis of achieving good quality cathode includes the control of electrolyte impurities and consistency of specific process conditions. The commercial operation of emew nickel technology has been successfully implemented and has demonstrated the ability to produce high quality nickel cathode from refinery bleeds. This paper emphasizes the importance of upstream impurity removal to achieve the required nickel emew feed composition by evaluating the benefits of using selective precipitation as a purification scheme with the aim of improving the overall nickel recovery while ensuring suitable nickel concentration in the advanced electrolyte is achieved. Nickel electrowinning is similar to other electrowinning processes that employ insoluble metal anodes & cathodes. It requires the passage of direct current between two electrodes that are immersed in a conductive, aqueous solution of nickel salts. For the recovery of nickel from solution, the most common methods are electrowinning and hydrogen reduction. Electrowinning usually occurs from sulfate, chloride or mixed sulfate/chloride electrolytes. In sulfate electrolytes, nickel electrowinning cells are normally designed to achieve specific criteria as outlined below (Robinson & Tuppa, 2002):"

Jan 1, 2017

By P. H. Agson Gani, T. Sitorus, N. P. Widodo

"PT ANTAM UBPE Pongkor underground mine use blasting to develop its tunnels which will cause poisonous and dangerous gases trapped inside mine. To analyze this case, a study of mine ventilation, the dispersion of carbon monoxide (CO) gas concentration and diffusion coefficient is commenced. At the end, the re-entry time formula will be determined. Results indicate that this study is site specific and could only be applied in the place this study executed. The aim of this study is to be further developed by applying Principal Component Analysis (PCA) to find a universal re-entry formula. KEYWORDS Mine Ventilation, Re-Entry, Smoke Clearing, Diffusion Coefficient, Carbon Monoxide Gas, Gas Dispersion INTRODUCTION Pongkor underground mine is using cut and fill as its mining method. Thus, its development and production processes require blasting to develop its tunnel. This process caused poisonous and dangerous gases spread and trapped inside the mine, one of them is carbon monoxide (CO) gas. CO is formed in an unbalanced reaction of explosives detonation and could be the cause of headache, blackout and death to people who inhale CO at certain concentration (McPherson, 2011; Hartman, Mutmansky, Ramani, & Wang, 2012). Mine ventilation system is installed in the mine to resolve this problem. Mine ventilation play an important role to disperse CO gas by absorb the poisonous/dangerous gases and deliver clean air into mine. The important parameter is diffusion coefficient, because diffusion is affecting particulates or gasses spreading from its sources throughout the mine. Diffusion coefficient is the total diffusion in axial direction of turbulent flow mainly by convection of bulk motion, advection and eddy diffusion, while the effect of molecular diffusion is appreciably negligible (Widiatmojo et al, 2015). Taylor (1953, 1954) develops a theory about the dispersion by inducing a slow stream of solvent into a capillary tube. Taylor used Reynolds assumption of radial diffusivity to be analogous with the transfer of the matter in turbulent flow as well as the transfer of momentum and heat. Then, Taylor proposed the formula of diffusion coefficient, D (m2/s), against pipe diameter and turbulent shear velocity are as follow:"

Jan 1, 2019

By M. L. Wacker

"Cigar Lake high-grade uranium mine in Saskatchewan is operating after 25 years of test mining, construction, and mine flood remediation. Factors include ground stability, groundwater control, radiation exposure, and ore handling. A 10 year test program resulted in validating “jet boring”, a non-entry mining method involving artificially freezing the orebody and surrounding rock; tunnelling to develop access crosscuts below the orebody; installing cased pilot holes through ore; extracting ore using rotating high-pressure water jets within pilot holes; and cavity concrete backfilling. Ore slurry is prepared underground, pumped to surface, and trucked to McClean Lake mill for processing to uranium concentrate.RÉSUMÉ Après 25 années d’essais sur les méthodes minières, de construction et d’assainissement suivant les inondations à la mine, l’exploitation de minerai à haute teneur en uranium Cigar Lake, localisée dans la province de la Saskatchewan, est opérationnelle. Les principales difficultés concernent la stabilité du terrain, le contrôle des eaux souterraines, l’exposition aux rayonnements et la manutention du minerai. Un programme d’essai de 10 ans a abouti à la validation du « forage à érosion », une méthode minière qui consiste à congeler artificiellement le corps minéralisé et les roches environnantes ; à creuser des tunnels pour développer des travers-bancs d’accès en dessous du corps minéralisé ; à installer des puits de fondation pilotes à travers le minerai ; à extraire le minerai à l’aide de jets d’eau à haute pression dans les puits pilotes ; et à remblayer les cavités avec du béton. La boue de minerai est préparée sous terre, pompée vers la surface puis transportée par camion jusqu’à l’usine de concentration de McClean Lake pour le traitement afin d’obtenir du concentré d’uranium.INTRODUCTIONThe Cigar Lake deposit is in northern Saskatchewan, 660 km north of Saskatoon, Saskatchewan, Canada, at the east edge of the Athabasca basin (Figure 1; Bishop, Mainville, & Yesnik, 2016). The operation is jointly owned by Cameco Corporation, AREVA Resources Canada Inc., Idemitsu Canada Resources Ltd., and TEPCO Resources Inc. Cameco has been the operator of Cigar Lake since January 2002. The discovery hole was drilled in 1981. Commercial production was declared in May 2015 and the Phase 1 operation will have a mine life of 15 years."

Jan 1, 2017

By P. Mišcevic, B. Kavur, I. Vrkljan, N. Štambuk Cvitanovic

It is known from earlier and recent research that mechanical properties of intact rock like uniaxial compressive strength (UCS), Young's modulus (E) and Poisson's ratio (?) are influenced by shape deviations of test specimens as deviations from the ideal cylinder. That impact can be significant at certain level of inaccuracy of specimen preparing, and it should be objectively evaluated and controlled in testing. The effects of intact specimens side straightness, ends flatness, ends parallelism and perpendicularity to the specimen axis, on UCS, E, and ?, measured in several actual ways during laboratory compression tests, were determined by previous research on 90 homogeneous specimens of limestone. In this paper, we subject these new experimental results to Response Surface Methodology (RSM) to model the mentioned dependence, to identify significant connections of variables and to evaluate the conclusions obtained directly from experimental phase. This study indicates how the responses of the model (outputs) – parameters UCS/E/??of limestone rock depend on factors (inputs) – parameters of specimen shape deviations like flatness R, parallelism P and perpendicularity O, assuming modern test machines with spherically seated upper platen. Starting from general RSM model with three factors (R, P, and O), we investigated the multiple linear regression models of specific mechanical property (UCS, E, and ?). Using the NCSS program ("NCSS 2004 and PASS 2005") in several steps, final models with very high coefficients of determination were developed for properties with the most evident effects of specimen shape deviations: nine models for strength UCS and UCS50 (equivalent UCS for specimen with 50 mm diameter), and three models for ?L (Poisson's ratio calculated from axial deformations measured on the entire specimen length). These statistical models with their response surfaces further strengthen and confirm the results and conclusions from the experimental phase. The critical values of R, P, and O are established using an additional statistical analysis to determine the lower and upper engineering limits. These findings set the basis for the new eligibility criteria for specimens of limestone (and similar rock with UCS about 100-150 MPa) in further testing of strength and deformability.

Jan 1, 2015

By F. L. Pellet, S. Maiolino

"The determination of rock bolt contribution to reinforced joint shear strength is still a challenge, especially for assessing reinforced rock mass stability. For this purpose, several experimental studies have been performed during the last decades, mostly on small scale rock joint and bolt specimens. However, to accurately assess the rock bolt contribution, scale effect has to be accounted for. For this reason full scale lab tests are required as an alternative to in situ tests for which boundary conditions are more difficult to control.In this paper the results of an experimental program carried out with a large shear box, dedicated to test bolts in full scale conditions is presented. Different rock bolt diameters and different rock bolts inclination with respect to the shear plane were tested Experimental results were satisfactorily compared with an analytical model which is able to compute the contribution of the rock bolt to the shear strength of the joint as well the associated displacement of the joint. These conclusions allows us to validate the model in order to help the designer of reinforced rock engineering structures, such as slope or underground openings, to precise the optimum installation of rock bolts. INTRODUCTIONFully grouted rock bolts are commonly used for rock masses reinforcement to ensure the stability of rock slopes and underground cavities. For this purpose, the determination of rock bolt contribution to reinforced joint shear strength is of the utmost importance. During the last decades, several experimental studies have been performed to investigate the behavior of bolted rock joint. For obvious reasons, almost all the experiments were achieved on small scale bolted rock joint specimens (Bjurström, 1974; Azuar, 1977; Dight, 1983; Egger & Fernandes, 1983; Schubert, 1984; Spang & Egger, 1990; Egger & Zabuski, 1991). These studies made it possible to assess the influence of different parameters such as the bolt’s diameter, the number of bolts, the angle between the bolt and the joint, the nature of the rock, the friction and the dilatation angle of the joint. However, to accurately assess the rock bolt contribution, scale effect has to be accounted for (Vallier et al., 2010). For this reason full scale lab tests have been performed as an alternative to in situ test for which boundary conditions are more difficult to control."

Jan 1, 2015

By A. Danaei, A. McLean, M. Barati, C. Ravindran

"The aluminum industry generates about 90 million tonnes of red mud each year. Previous research shows it could be utilized as a refining flux with a high capacity to absorb phosphorus and sulphur from hot metal in the steel industry. The present study was undertaken to evaluate the melting properties of such fluxes, as it affects the effectiveness of the flux. The results show that the melting behavior of red mud is strongly affected by lime addition and the characteristic melting/softening temperatures reach minimum VALUES (at 32.7 wt% CaO. From these findings, a correlation was established between melting behavior and optical basicity. This allows one to adjust the composition of the flux based on the process requirements. INTRODUCTIONThe aluminum industry generates about 90 million tonnes of bauxite residues each year. This residue is usually red in color because it contains a substantial amount of iron oxide. The red mud, as it is called, is a solid waste with a high concentration of sodium oxide, high pH (10 to 13), and high alkalinity, and thus is harmful to many forms of life. Traditionally, the material is stored in large tailings ponds within the plant’s vicinity (Power, Grafe, & Klauber, 2009). Development of solutions for safe disposal or preferably using this residue for other industrial processes or applications could help restore polluted locations and eliminate a negative impact on the environment (Haake, 1988; Power et al., 2009; Yan & Xuegong, 2010).The mineralogy and chemical composition of red mud depends on the quality of the bauxite and refining process parameters. In general, it consists of iron oxide (Fe2O3), aluminum oxide (Al2O3), titanium oxide (TiO2), sodium oxide (Na2O), silicon oxide (SiO2), and calcium oxide (CaO) (Power et al., 2009). Like most ores and soils, bauxite can contain trace quantities of metals such as arsenic, beryllium, cadmium, chromium, lead, manganese, mercury, nickel, and naturally-occurring radioactive materials, such as thorium and uranium. Most of these trace elements stay in the residue (Power et al., 2009)."

Jan 1, 2012

By Y. Y. Yemelyanov, S. S. Gudkov, A. V. Boldyrev, A. V. Bogorodskiy, S. V. Balikov

"A series of tests to optimize pressure oxidation- carbon-in-leach process (POX-CIL) of goldbearing flotation concentrate with the addition of sodium chloride and activated carbon were carried out. Flotation concentrate which was generated during primary ores concentration from a large Russian deposit was used for these tests. The tests were performed with different concentrations of sodium chloride. It was found that the required sodium chloride concentration for gold leaching was 5 g/L. The tests performed with different additions of activated carbon showed that the amount of activated carbon should be at least 6% of the concentrate mass. The rate of sulfides oxidation was 67.7–99.8 %. The highest gold recovery was 98.6 %.INTRODUCTIONThe majority of gold-bearing ores are recommended to classify as amenable to cyanidation and refractory. Processes at elevated pressures and temperatures have become increasingly important in base metals hydrometallurgy (Lodeischikov, 1999, 2007; Naboichenko, Shneerson, Kalashnikova, & Chugaev, 2009; Thomas, 2005).Current pressure autoclaves – cyanidation flow sheets are capital intensive due to numerous circuits and the use of environmentally-unfriendly sodium cyanide. The use of halide-based lixiviants during pressure oxidation of precious metals can be a promising technique for refractory sulfide goldbearing mineral raw material hydrometallurgical processing (Fleming, 2002, 2007, Kotlyar, Meretukov, & Strizhko, 2005).In this paper, we presented the results of the research on finding the optimum process parameters of pressure oxidation using an adsorbent for a refractory gold-bearing concentrate. A proposed flow sheet involves (Bogorodsky, Yelelianov, & Balikov, 2012):1. Gold-bearing sulfides oxidation followed by precious metals dissolution and the formation of gold and silver chloride complex;2. Reaction of the precious metals chloride complex with a carbon-based adsorbent;3. Precipitation of precious metals onto the adsorbent by EW and smelting of cathode precipitates into Dore bullions.This process allows POX of gold-bearing sulfides, precious metals dissolution and their precipitation on the adsorbent to be executed in one single vessel. This study found that the most suitable lixiviant was sodium chloride. Fleming (2002) suggested that in the presence of a halide-based reagent (e.g. chlorine- ion reaction), the dissolution of gold during POX is achieved according to reaction 1:"

Jan 1, 2016

By Long Han, A. V. Kalinin, Xiujian Luo, Xiaobo Wang, Xiaoou Xia

"Inertia vibration crusher is a kind of vibration equipment which crushes ore by vibration. When the inertia vibration crusher works, ore between the two moving jaws is subjected to the high frequency contact force, which is produced by the two moving jaws with high frequency synchronous reciprocating motion. The synchronous motion of the two moving jaws depends on the self-synchronous feature of the inertia vibration crusher. To study the self-synchronous feature of the equipment, the dynamic model was established, in which relative parameters were taken into consideration. The kinematic coupling relations of the assemblies are discussed, and appropriate calculation method is chosen to solve the vibrating differential equation. Whether the two vibration exciter can realize synchronous operation depends on the ability of the vibration system's capture moment. Results show that though the two rotors’ motors and damping coefficients are different, and two jaws’ damping and stiffness coefficients are also different, as angular velocities of the two unbalanced rotors reach a certain value, the vibrating system can be stable. Their angular velocities tend to be equal, and the swings of the two moving jaws can be the same. The horizontal vibration and swing of the frame are large in a few seconds after starting the machine. When the system runs stably, the horizontal vibration and swing vanish, and the vertical vibration is stable. The study and its results can provide reference for the optimization design and parameter setting of inertia vibration crusher and related vibratory equipments.INTRODUCTIONMaterials can be easily broken by using the inertia force of the vibration exciter, which can effectively realize the selective crushing, reducing excessive combinations and the energy consumption, as introduced by Zhang in 2005. The initial micro crack between crystals in the material increases and new cracks can be manufactured because of the high frequency impact and the extrusion of the vibration crusher, so vibration crushing equipment can make it possible for any high strength brittle material to be broken theoretically. Inertia cone crusher and inertia vibration crusher have been successfully used in the treatment of metallurgical slag and construction waste, and it verifies the efficiency of vibration crushing."

Jan 1, 2016

By Benoît Plante

La mine Tio (QIT Fer et Titane Inc.) exploite à ciel ouvert un gisement d?ilménite massive depuis 1950, générant jusqu?à maintenant plus de 70 Mt de roches stériles potentiellement génératrices de drainage neutre contaminé (DNC), dont une partie est submergée dans le lac Petitpas, au nord de la mine. Si généralement l?ennoiement des rejets miniers a un effet bénéfique pour limiter la contamination des eaux, cela reste à prouver pour ce qui est des stériles générateurs de DNC. Des essais en réservoirs ont été réalisés afin d?évaluer la réactivité de trois différents types de stériles submergés, qui ont été choisis en fonction de leur teneur en ilménite. Afin d?évaluer l?impact de la matière organique sur la réactivité des stériles submergés, chaque type de stérile est étudié en immersion simple ainsi que combinée à des sédiments prélevés au lac Allard, à proximité de la mine, d?où l?eau utilisée dans les essais a aussi été prélevée. L?évolution des teneurs en Ca, Mg, Si et Ni durant les 8 premiers mois d?étude démontrent que les stériles immergés sont réactifs, mais l?impact de la matière organique demeure pour l?instant difficile à préciser. Tank tests on Tio mine waste rock The Tio mine (QIT Iron and Titanium Inc.) exploits a massive ilmenite ore as an open pit since 1950, producing over 70Mt of potentially contaminated neutral drainage (CND)-generating waste rocks. While the underwater disposal of mine wastes generally show a beneficial effect on water contamination, this method still needs to be approved for CND-generating waste rocks. Tank tests were realized in order to evaluate the reactivity in underwater conditions of 3 different waste rock types, chosen with regards to their ilmenite content. In order to evaluate the impact of organic matter on the reactivity of underwater waste rock, each waste rock type was studied in simple immersion and in combination with sediments sampled at Allard lake, located near the mine, where the water for the tests was also sampled. The evolution of Ca, Mg, Si and Ni during the 8 first months of testing show that the waste rocks are reactive underwater, but the impact of the organic matter is till hard to define.

Nov 1, 2008

By Jorgen Elbrond, Yve Lizotte

"A mathematical procedure for determining the underground mining level layout which minimizes the total costs of excavation and haulage is described. This procedure has the advantage over previous graphical procedures of being easily amenable to microcomputers. The paper demonstrates through examples how the procedure can be applied to minimizing discounted costs of level layout as well as providing the optimal location of a production shaft.IntroductionIn recent years there have been numerous publications in mining journals concerning the minimization of mine haulage costs. With the rapid escalation of energy costs during the last decade it is not surprising that several studies applying queuing theory, simulation and mathematical programming to mining related transportation problems have been successfully undertaken. Because of the increasing availability of various sizes of computers these techniques have gained considerable popularity as evidenced by the numerous commercial packages presently being marketed.The publications concerned with haulage cost minimization are generally concluded along the lines of &apos; ... haulage costs at production rate x will be minimized by assigning y units to location z...&apos;. Details about the route followed and whether it guarantees a minimization of costs are seldom considered. Route data has to date been manually resolved and used for input to developed programs. It would appear that no program has been developed to date which simultaneously minimizes costs by both fleet assignment and routing network resolution.Another important factor in transportation problems is the investment cost associated with the routes; road construction costs or, in the case of underground levels, drift excavation costs. Except for special cases the transport network which minimizes haulage costs only will not provide a minimum excavation cost solution.Zarnbo(1) illustrates by graphical and mathematical procedures how central &apos;facilities&apos; can be located to simultaneously minimize investment in the transport network and haulage costs. Unfortunately these procedures and others recently applied to mine haulage problems do not provide solutions to the generalized problem. Also because these procedures are geared to graphical solutions and hand computations whereby certain possibilities can be &apos;visually&apos; eliminated, they can be tedious to program and present storage capacity constraints with current microcomputers."

Jan 1, 1985

By J. Chlan

"Dryer DescriptionProctor and Schwartz Continuous Conveyor DryerThe Proctor and Schwartz Continuous Conveyor Dryer has been in operation since July 1958, and comprises six unit• - an 8• wide single conveyor with roller extruder, insulated housing, type 304 stainless steel circulating and exhaust fall system, steam heating coils, temperature controls and discharge crusher rolls. Entire dryer dimensions are 52’ x 12'0""weighing 53,000 lbs,Extruder rolls - setting is 1/8"" (Drive 3 HP 1800 RPM) clearance off the extruder screen.Conveyor - consists of 151 interlocking pans, measuring 8"" x 8' (2 HP 1200 RPM) One Exhaust Fan (5HP - 900 RPM)Steam Coils -- l"" steel pipe - with steel fins -- each coil measures 16' 2’’- 64 coils in the No, 1 Compartment- 64 coils in the No, 2 CompartmentDryer OperationThe yellowcake slurry at 28% solids is pumped to an 81 x 8' Peterson Filter. The filter media presently being used is a Neotex 4372 blanket, being 100% staple fibre nylon, 12 oz per square yard with air porosity of 9 CFM's. The cake discharge at 45 - 50% moisture falls into the roller extruder. Extrusions are formed by forcing the material by rolls through a perforated plate moving back and forth and depositing the spaghetti-like extrusion on onto the dryer-conveyor.The conveyor now carries the extruded material through the heating chamber•, The feed end of the dryer will be referred to as No. 1 Compartment, with temperature control set at 280""F. The circulating fans take the hot air off the coils and circulate the heated air through the perforated openings in the dryer conveyor pane, After passing through the set of steam coils and circulating fan in No, 1 Compartment, the material then goes through No, 2 Compartment where the temperature is set at 305'F, Final material then discharges through a set of crusher rolls set at ~"". Moisture of final dried product runs at less than 2%.The dryer conveyor load is usually run to a 3"" - 4"" depth load. Conveyor speed at approximately 90 minutes for load to pass through. Load onto the conveyor is controlled by boot level and speed of the 8' x 8' filter. The dryer steam coils are water-washed twice a month."

Jan 1, 1972

By T. T. Chen

A detailed mineralogical study was carried out to characterize the products generated in a conventional copper refinery anode slimes treatment circuit. The anode slimes, which are first leached in sulphuric acid media under an oxygen pressure to dissolve the copper and much of the tellurium, were found to contain various Ag-Cu selenides, PbSO4, Ag, Au and BaSO4. The resulting Ag2Se, Ag3AuSe2, Se, Au, PbSO4, BaSO4, SnO2 and silicate-rich leach residue is dried and pelletized. It is subsequently roasted to convert the selenium to Ag2SeO3, volatile SeO2 and water soluble Na2SeO4. The roasted product, which was found to consist of Ag2Se, PbSe, PbSO4, BaSO4, Ag3AuSe2, Au and Sn02, is smelted and refined in a Dore furnace to produce a Dore metal that contains a (Ag,Au,Pd,Cu,Pt) alloy together with traces of CuO and a Cu-Pb oxide phase. Parting plant mud shown to contain AgC1, Ag, Au, (Au,Ag,Pd), Ag2Cu2O3 and Ag20, and scrubber mud containing PbSO4 and AgC1 are also fed to the Dore furnace. The Dore furnace sequentially separates a silica slag which was found to consist of Ag, Sn02, BaSO4, Pb-Sb oxide, Fe-Sb-Ni-Cr oxide and a Pb-rich silicate phase, a soda-rich slag containing Na2CO3.H2O and Na2(Se,Te)03, and a niter slag containing Na2TeO3, Na2(Se,Te)03 and a Na-Te-Se-Pb-Ba-Cu oxide phase. The Dore metal is electrorefined in Moebius cells to yield high-purity silver and a gold mud which was shown to consist of a (Au,Ag,Pd,Cu,Pt) alloy and traces of CuO. Silver is leached from the gold mud and the resulting gold sand is cast into anodes and electrorefined in Wohlwill cells to produce pure gold.

Jan 1, 2007

By Peter Heine

Diavik Diamond Mines Inc. (DDMI) has treated systems development as an integral part of the construction project when it built Canada?s second diamond mine. Fully aware that the proper collection and processing of operational data is needed to drive business decisions during production and planning, key Performance Indicators (KPIs) were defined to effectively manage operations when the mine went into production. The Production Information Management System (PIMS) allows KPIs to be measured, reported, and transferred to other systems in a reliable and convenient manner. PIMS provides a mechanism to collect real time production data from the various control systems around the site and acts as a tool to ?drill-down? and establish the important cause-effect relationships that impact the value of a KPI. Thus PIMS provides a data collection, storage, management, and an environment in which cause-effect relationships can be analysed and statistically verified. This understanding of the real cause-effect relationships, close to the source of the data and in the context of the operation, can be used to improve both operations and maintenance performance. The PIMS includes the PI Database implementation, its associated external interfaces with the various Control Systems, Cleaning Packaging Weighing System, Environmental System, Enterprise Asset Management (EAM) System, and Diamond Tracking System (DTS), as well as laboratory data collection, custom applications (downtime tracking, data reconciliation) and user clients. The interface with the EAM system provides material flow quantities and equipment availability on which the plant performance reports are based. The transfer of equipment usage to the EAM system is fed into the maintenance notifications and work orders functionality in the EAM. The environmental system interface provides the mechanism for capturing water consumption data required to generate the various regulatory reports. The interface to the cleaning-packaging-weighing system provides the mechanism for capturing batch data for transfer to the DTS for diamond product tracking at the production splitting facility in Yellowknife. The PIMS lab application provides a means of getting sample data into the system for critical metallurgical metrics, and the data reconciliation application provides a means of manually verifying the data before it is published or passed onto other systems.

May 1, 2003

By P. Amelunxen, E. Herrera, L. Hill, J. Vanderbeek

It is well-known that the particle breakage mode that occurs in a semi-autogenous mill is significantly different from that which occurs in a ball mill, enough so to warrant very different lab scale breakage tests and scale-up models. This phenomenon, at the plant scale, leads to changing process constraints depending on the particular properties of the ore. For example, hard or coarse ores might bottleneck the SAG/AG mill throughput, while the ball mills might constrain throughput when milling soft or fine ores. Because the power draw of a ball mill is fairly constant compared to that of a SAG/AG mill, periods of SAG/AG mill bottlenecks lead to increased ball mill circuit specific energy consumption and a finer grinding circuit product size, which together constitute a loss of efficiency of the overall process. Because HPGR circuit throughput is less sensitive to changes in ore hardness, this situation is less common or severe in those circuits. Furthermore, the ball mills are somewhat decoupled from the upstream crushing circuits through the use of surge bins, which also helps to mitigate this effect. As a result, ore hardness variability constitutes a significant cost penalty that should be applied to SAG mill/ball mill/pebble crusher SABC circuits when evaluating the relative economics of different grinding circuit configurations. Nevertheless, the issue is by-and-large ignored, because most current HPGR trade-off studies are based on averaged ore hardness parameters. This paper provides an estimate of the magnitude of this penalty for a typical operation by using Monte Carlo simulation methods and plant data from Freeport-McMoRan’s autogenous, semi-autogenous, and HPGR-based comminution circuits. A case study from an in-house 96K t/d sulphide project is presented to illustrate the concept. It was found that by including variability effects, the trade-off NPV of the HPGR circuit over that of the SAG mill circuit increases to $84 million from negative $33 million, effectively reversing the original decision of selecting a SAG mill circuit for the fixed hardness case.

Jan 1, 2012

By John Keay, Douglas R. Shaw, Gregory J. Olson

"The results are presented herein of on-going laboratory investigations of heap bacterial oxidation as a pretreatment method for the recovery of sulfide-encapsulated gold from ore samples of the Rhodes Mining Lahoca deposit, located in northern Hungary. The ore contains just over 2 g Ault and as much as 6% sulfide, mostly as pyrite. Laboratory aerated column tests conducted at Colorado Minerals Research Institute (CMRI) showed that mild to moderate biooxidation of the finely crushed ore occurred rapidly in approximately three months, with cyanide gold recoveries of up to approximately 60%. The results contrast cyanide gold recoveries of less than 30% from non-pretreated ore. Mineralogical examination of biooxidized residues indicated that the mechanism of biooxidation of crushed ore was related to microorganisms following pathways along structural anomalies in the pyrite grains. Such selective biooxidation is an important result to minimize the biooxidation and aeration time and effluent neutralization costs in a commercial operation.IntroductionThis paper describes the development of a heap biooxidation process for the Lahoca gold project The Lahoca deposit is situated in northern Hungary, at the site of a former copper mining area. Lahoca is a large tonnage, relatively shallow, deposit amenable to open-pit mining Lahoca has the potential to produce I 00,000 ounces of gold annually for at least ten years at its minimum reserve base.The laboratory test work conducted initially by Rhodes Mining NL demonstrated that the Lahoca refractory ore is amenable to whole ore and concentrate oxidative pretreatment and cyanidation. Capital and operating costs, however, for such milled ore treatments were considered relatively high. Rhodes Mining subsequently evaluated heap leaching methods, particularly heap biooxidation pretreatment, as a process route that promised superior economics suitable for exploiting lower gold grade refractory ores.This paper focuses on the laboratory column (simulated-heap) biooxidation test work, particularly the proposed mechanism of selective microbial oxidation, wherein only a small amount of the sulfides are oxidized sufficient to allow commercially acceptable gold recoveries by conventional cyanide heap leaching. Selective or minimal biooxidation of sulfides is considered important to minimize biooxidation time and aeration requirements, as well as acid effluent neutralization costs."

Jan 1, 1998

By T. Bhambhani, O. Yavuzkan, D. R. Nagaraj

"Cu ore bodies commonly contain oxide Cu at the surface, with sulfide Cu content increasing with depth. The recovery of oxide Cu minerals by flotation is a longstanding challenge in the minerals industry, especially for high acid-consuming ores which would not be economical for direct acid leaching. Current practice of oxide Cu recovery involves sulfidization (often using controlled potential sulfidization or CPS) using NaSH (or Na2S) followed by flotation using traditional sulfide collectors. CPS has shown to improve recovery of oxide Cu but has the following limitations: a) HSE issues with NaSH, b) high consumption of NaSH, and c) inability to recover certain oxide Cu minerals because they are refractory to sulfidization. The oxide Cu flotation is further complicated by the presence of certain non-sulfide gangue minerals which adversely impact both recovery and selectivity.Over the past eight decades, numerous collectors have been proposed and evaluated for the direct flotation (i.e. without sulfidization) of oxide Cu minerals, the most researched of which is alkyl hydroxamate. While there are numerous publications dealing with the fundamentals of interaction of alkyl hydroxamates with single minerals, there are few publications which discuss the practical aspects of alkyl hydroxamate use in ore flotation, particularly their use with sulfidizing agents. Case studies in this paper include methods to identify optimum combinations of sulfidizing agents and oxide collectors to maximize recovery for various types of ores. It was observed that some ores do not require any sulfidization, while others require at least partial sulfidization to improve efficacy of AHX. Depending upon the ore type and mineralogy, recovery improvement in the range of 5 to 15% units, over and above that achieved with CPS, has been observed with the use of AHX. For ores requiring high dosages of NaSH, it was shown that AHX can be used to reduce the NaSH consumption significantly. The challenges associated with the presence of non-sulfide gangue minerals in oxide copper ores are included, and the use of modifiers to alleviate the associated problems and enhance the performance of AHX is discussed."

Jan 1, 2016

By M. Saghaeian, R. Hejazi, Sheikhzadeh. V., A. Abazarpoor

"The morphology of iron ore concentrate particles is known to influence several properties of iron ore pellets, including drop number, compression strength, and reduction properties. This study aimed to determine why grinding methods and particle morphology influence green pellet properties. Particle morphology can be directly related to the grinding method: ball mill (BM) or high pressure grinding roll (HPGR). In this research, two iron ore concentrates, namely Gol-e-gohar and Ardakan, were ground by a BM and HPGR to produce a suitable Blaine value for pelletizing (nearly 1,900 cm2/g). Morphological features of particles were subsequently investigated by sieving and cyclone sizing for particle size distribution, the Brunauer-Emmett-Teller (BET) and Blaine methods for specific surface area (SSA) and scanning electron microscopy (SEM) for the evaluation of shape descriptors. It was concluded that HPGR resulted in generating a greater proportion of fine particles compared to ball milling. The BET results showed that the SSA of HPGR pellet feed was higher than that from the BM due to a greater proportion of cracks, indents and bulges and the creation of new fracture surfaces. SEM images processed by ImageJ software indicated that particles ground by the BM tended to be more rounded and less elongated than HPGR particles because of the breakage model of each method. To show the effect of morphology on the green pellet quality, green pelletizing was performed in a pilot pelletizing disc. The HPGR pellet feed had a higher drop number in comparison to the BM pellet feed, due to the angular and rough shape of the particles.INTRODUCTIONThe demand for fine or ultra-fine particles as feed material for ceramics, composite materials, and mineral processing is on the rise (Kotake, Kuboki, Kiya, & Kanda, 2011). The final concentrate of iron ore processing plants (filter cake) has a size range roughly between 0 and 300 µm, depending on the liberation of Fe containing particles (Meyer, 1980). In general, to produce a suitable pellet feed of appropriate quality, Blaine numbers of 1800–2000 cm2/g should be achieved (Van der meer, 2015)."

Jan 1, 2016

By S. R. McCutcheon, D. R. Lentz, W. S. Downey

"Abstract - The Little Falls member of the Nepisiguit Falls Formation is situated in the northern part of the Brunswick Belt of the Bathurst Mining Camp and has been interpreted as the distal equivalent of proximal tuffaceous rocks that host the stratiform Brunswick No. 12 and No. 6 Pb-Zn massive sulfide deposits. It comprises fine-grained, greenish-gray tuffaceous sandstone in the lower part, and coarse-grained, crystal-rich tuffaceous sandstone in the upper part. Petrographic evidence suggests that these rocks have a turbiditic origin. The Little Falls member is underlain by the Vallée Lourdes member, mainly composed of relatively shallow-water calcareous rocks, and is conformably overlain by Mn-rich sedimentary rocks, mainly red argillites that host the Tetagouche Falls Mn-(Fe) deposit. All these rocks are considered to belong to the Nepisiguit Falls Formation, part of the Ordovician Tetagouche Group. Whole-rock geochemical data from the fine-grained tuffaceous sandstone and coarse-grained tuffaceous sandstone indicate that the two units of the Little Falls member are distinct. Zr and TiO2 contents, and total rare earth element (REE) values are higher in the coarse-grained unit (average Zr/TiO2 = 0.040, average SREE = 247 ppm, n = 6) than in the fine-grained unit (average Zr/TiO2 = 0.048, average SREE = 158 ppm, n = 17), which can be attributed to the variation in crystal content between the two units. Both units are HREE-enriched and have elevated La/Yb relative to the typical Nepisiguit Falls Formation. Overall, the geochemical data combined with evidence from the bounding units suggest that the Little Falls member was deposited in relatively shallow water, possibly in a near-arc environment. The relationship of volcanic facies within the Nepisiguit Falls Formation and the geochemistry of these facies indicate strongly that fine grained, reworked tuffaceous rocks, regardless of whether they are the distal equivalents of proximal tuffaceous rocks, are not associated with the major ore-bearing horizons of the Bathurst Mining Camp. Sommaire - Le Membre de Little Falls de la Formation de Nepisiguit Falls se retrouve dans la partie nord de la Ceinture Brunswick du Camp Minier de Bathurst ou elle a été interprétée comme l’équivalent distal des roches tuffacées proximales hôtes des gisements de sulfures massifs de Pb-Zn stratiformes Brunswick No.12 et No.6. Il consiste en grès tuffacé à grains fins gris verdâtre dans sa partie inférieure et en grès tuffacé à grains grossiers riche en cristaux dans sa partie supérieure. Les données pétrographiques suggèrent que ces roches ont été déposées par des courants de turbidité. Le Membre de Little Falls repose sur le Membre de Vallée Lourdes, lequel consiste principalement en roches calcareuses déposées en eau relativement peu profonde; il est de plus recouvert en concordance par des roches sédimentaires manganifères, lesquelles consistent principalement en argilites rouges hôtes du gisement de Mn-(Fe) de Tetagouche Falls. Toutes ces roches appartiennent à la Formation de Nepisiguit Falls, laquelle fait partie du Groupe de Tetagouche, d’âge Ordovicien. Les données lithogéochimiques des grès tuffacés à grains fins et à grains grossiers indiquent que ces deux unités du Membre de Little Falls sont distinctes. Les teneurs en Zr et en TiO2, ainsi que la teneur totale en Éléments des Terres Rares (ÉTR) sont plus élevées dans l’unité à grains grossiers (Zr/TiO2 moyen = 0.040, SREE moyen = 247 ppm, n = 6) que dans l’unité à grains fins (Zr/TiO2 moyen = 0.048, SREE moyen = 158 ppm, n = 17), ce qui pourrait s’expliquer par la variation de la quantité de cristaux dans chacune de ces deux unités. Chacune de ces deux unités présente un enrichissement en ÉTRL ainsi qu’un rapport La/Yb relativement plus grand que ce qui est typiquement observé dans la Formation de Nepisiguit Falls. Les données géochimiques considérées conjointement à l’information provenant des unités adjacentes suggèrent que le Me"

Jan 1, 2006