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The surface properties of eight coal samples were studied by measuring contact angles, coal oxidation, equilibrium moisture and film flotation. The penetration tests were carried out with do de cane, while dodecane and MIBC were utilized in batch flotation tests and in the simplified release analysis. Coal floatability results from the properties of coal organic matter and coal liberation. While the wetting of coal by water seems to be determined by the surface properties of coal organic matter, wetting by hydrocarbons correlates very well with the content of coal mineral matter.

Jan 1, 1992

By D. B. Dow

The presence of sulphur compounds in petroleum and its products is, generally speaking, undesirable, and the problems involved in removing such compounds are of great importance to the petroleum refiner and to the manufacturer of gasoline. There are several types of these compounds which are dissimilar in physical and chemical characteristics, as evidenced by different objectionable features which they exhibit, and special treatments have been developed to meet conditions existing in various products. This paper deals with the treatment of natural-gas gasoline for the removal of certain sulphur compounds which, if not removed, impart on objectionable odor and in addition badly discolor the product. The presence of this particular type of sulphur compounds is detected by the "doctor" test.* In some instances natural-gas gasoline is purchased on "doctor" test specifications, and the ordinary purchaser, while not buying on "doctor" specifications, is insistent in his demand for a water white product. Gasoline which fails to meet the "doctor" test, if not received by the buyer within a few weeks after time Of manufacture, may be "off color" enough to warrant a deduction from the market price.

Jan 1, 1923

By J. J. Sammarco

Light emitting diodes (LEDs) are emerging as viable replacements for incandescent-based cap lamps used in mining. The photometric and energy characteristics of these light sources differ in important ways. The present paper describes the performance of LED and incandescent sources in cap lamps in terms of correlated color temperature, color rendering, light output, electric power, ambient temperature and airflow, and light source aging. Importantly, these characteristics can influence a miner?s ability to spot mining hazards thus impacting safety. Secondly, some of these characteristics interact with the operating life of the cap lamp?s battery power, such that differences between LED and incandescent sources can be magnified toward the end of a 10­hour battery discharge cycle. Empirically, we have determined that after 8 hours at an ambient temperature of 25 °C, the average light output of an incandescent cap lamp can decrease to about 69% of its initial value when powered by a lead-acid battery and it can decrease to about 65% of its initial value when powered by a nickel-hydride battery. An LED-based cap lamp using a constant current drive circuit can maintain about 96% of its initial value when powered by a nickel-hydride battery. Real-world tests addressing the effects of ambient temperature and airflow on the light output of an LED and incandescent cap lamp were conducted in the NIOSH Safety Research Coal Mine (SRCM). The LED cap lamp yielded a vertical average illuminance improvement of approximately 9.5% and the INC cap lamp yielded a vertical average illuminance degradation o f approximately 4%. The differences between LED and incandescent cap lamps were further quantified by the calculation of ?mesopic luminance? data that indicated for the same photopic luminance (i.e., as measured using a conventional light meter) the LED cap lamp could be up to 38 % more efficient than the incandescent cap lamp with a lead-acid battery at the end of the 10-hour driving cycle. Lastly, accelerated life tests were used to empirically determine light output depreciation as the incandescent light source age approached its useful life. There was about a 35% decrease in light output. This is quite considerable, especially given that the light output will decrease an additional 30% to 45% over the period of a 10-hour shift. The implications of the differences between LED and incandescent sources are discussed. This information is crucial in determining how visual performance could be affected for real-world conditions where batteries discharge during the work shift and as the light source ages. To date, only idealized conditions have been used for LED and incandescent cap lamp visual performance research.

Jan 1, 2008

By Jerzy A. Mielczarski

The separation of albites from quartz by flotation applying the conventional HF-methods is no longer acceptable from an environmental and health point of view. Therefore, the search for a new reagent scheme without using HF depressor for separation of albite from quartz is under consideration. The flotation behaviour of ore mineral components depends on the produced hydrophobic or hydrophilic surface coverage (chemical functionalization). Currently we have excellent possibility of monitoring surface composition and structure at molecular and atomic levels at surfaces of natural minerals contacted with aqueous solutions of collectors, activators, depressants which is vitally important for the understanding of the surface chemistry that govern selective and efficient flotation. Detailed surface characterization of minerals before and after their exposition to different solution conditions was performed by the most modern spectroscopic techniques such as developed by us the infrared external reflection technique combined with spectral simulation and X-ray photoelectron spectroscopy (XPS). It is possible to monitor surface reactions which facilitate the separation process and those which bring disadvantage to selective flotation. At first we found that a small amount of ?mineral impurity? presented in natural ore could play important role in selective hydrophobization process. It was found that the pH of solution (parameter possible to control) and natural mineral impurities present in mineral samples (parameter related to ore origin) play a very important role in the separation process. Another important parameter is interaction between minerals, quartz and albite, present in aqueous solution. The limitation of flotation separation resulting from chemistry will be discussed. Moreover, the most promising scheme for separation of albites from quartz will be examined.

Jan 1, 2014

By Xiang Sun

Microwave heating has been used in numerous industrial processes due to its great advantages when compared with conventional heating methods. However, microwave heated products can be affected by non-uniform temperature distribution resulting from the mechanisms of microwave heating. To overcome this problem, a critical step is to have a temperature-time profile. In order to characterize and evaluate microwave heating effects, an accurate temperature measurement is needed. This paper discusses the possibility of applying several temperature measurement techniques in microwave processing. Both contact and non-contact methods are introduced and compared.

Jan 1, 2006

By A. V. Kuznetsov, R. I. Kamkin, V. M. Paretskiy, A. Y. Mamaev, V. P. Bystrov, A. S. Vernigora

"Vanukov furnace technology is an efficient, proven pyrometallurgical injection technology, used extensively in Russia and Kazakhstan for a number of different applications. The technology was most widely adopted for processing copper sulfide concentrates for matte in smelters in Norilsk, Revda (Russia) and Balkhash (Kazakhstan). The following applications also were developed and tested at industrial scale: treatment of sulfide lead and lead-zinc concentrates, laterite nickel ore, production of cast iron, treatment of antimony gold-containing ores, and municipal solid waste. In this paper, current experience of Vanukov furnace application to these technologies is described with a number of general development trends and new areas of application.IntroductionAt the present time, the Vanukov process, developed at the Moscow State Institute of Steel and Alloys at the Department of metallurgy of non-ferrous, rare and noble metals with collaboration with other research organizations, is a highly efficient technological solution for processing different kinds of raw materials. The process was invented by Professor Andrey Vladimirovich Vanukov, whose research work began in 1949. From 1956 to 1975 test runs of the technology were carried out at the smelters in Norilsk and Balkhash. In 1976 a pilot Vanukov furnace was built in Ryazan. Furnace designs was modified to suit the various test programs. A major objective of each experiment was the determination of optimal working conditions for processing different types of raw materials such as copper, copper-nickel, copper-zinc, lead or pyrite concentrates, and materials containing secondary lead and zinc. After the death of Andrey Vladimirovich Vanukov in 1986, this technology and furnaces based on the technology were named after him: “Vanukov process” and “Vanukov furnace”. Today, the following furnaces based on Vanukov technology are either working or were tested at semi-industrial scale: three in Norilsk, two in Revda (Russia) and two in Balkhash (Kazakhstan) for treatment of copper sulfide concentrates for matte, one in Orsk (Russia) for processing laterite nickel ore, one in the Buruktal plant (Russia) for antimony gold-containing ores for antimony oxide sublimates and gold-containing metallic antimony, and one in China for processing sulfide lead and lead-zinc concentrates for production of black lead and zinc-containing sublimates."

Jan 1, 2011

By W. Z. Choi

In our previous work, a population balance model describing the simultaneous processes of size reduction and mineral liberation has been developed. The experimental verification of this model, however, has been limited to a binary mineral system containing only one composite particle class. When considering multiple classes of composite particles, the estimation of model parameters becomes much more difficult. In the present work, a procedure for estimating model parameters for a multiple composite class model has been developed. Emphasis is placed on the direct experimental determination of these parameters. The physical significance of the breakage rate function and the liberation function in characterizing the liberation process is also discussed.

Jan 1, 1987

By Shaik Jeelani, Esperidiana A. B. Moura, Vijaya K. Rangari, Roberta A. Lima, Rene R. Oliveira

This work present the preparation and characterization of biodegradable nanocomposites based on aliphatic-aromatic copolyester (PBAT)/polylatic acid (PLA) blend reinforced by TiO2 nanoparticle. The biodegradable polymeric nanocomposites were prepared by melting extrusion process using a twin-screw extruder machine. The influence of the TiO2 nanoparticle addition on mechanical and thermal properties of PBAT/PLA blend was investigated by tensile and impact tests, SEM, DSC and XRD analysis and the correlation between properties was discussed.

Jan 1, 2015

By E. L. Martheleur

A general expression for the electric power generated or consumed in a direct-current circuit is obtained by multiplying the reading of a suitable voltmeter connected across the terminals by the reading of an ammeter connected in the circuit. by the reading of an ammeter connected in the circuit. When alternating currents are considered, the product of the volts and amperes as obtained for direct currents does not generally represent the true energy involved; it is greater than this true energy and should be multiplied by a certain factor which may have any value between zero and unity, according to the conditions of the circuit. This factor is called the power-factor of the system, and expresses the ratio of the true energy over the apparent energy. For a three-phase system the expression of the apparent energy is [\/ 3 x E x I; ] while the expression of the true energy, that is, energy suitable for mechanical work, is [v? 3 x E x I x cos A.] The total current of a circuit corresponds to the reading of an ammeter connected in the circuit; it is the resultant of two currents. The first of these is in phase with the voltage, and is that portion which really produces mechanical work; the second is always in quadrature with the voltage, that is it may lead or lag the voltage by 90° according to the condition of the circuit. This second current does not produce any sensible work, and for this reason is sometimes called wattless current or reactive current.

Jan 1, 1924

By James R. Craig

The slags generated during gasification of petroleum coke are heterogeneous and con-sist of many different phases. These phases are important because their physical properties affect the operability of gasifiers and because they concentrate many elements that are present in the petroleum coke feed in only minor to trace quantities. An understanding of the chemistry and physical nature of these slag phases is necessary to predict behavior in the gasifier and in considering the ultimate use or disposal of the materials. Slags typically consist of silicate glasses, calcium-silicates, free iron-nickel metallic phases, iron sulfides, and aluminum oxide spinels enriched in iron, chromium, and vanadium. The partitioning of elements among these phases has been analyzed and will be discussed.

Jan 1, 1989

By AIME AIME

BEFORE proceeding with the papers scheduled for the ore and foundry session*, the teller's report on the election of officers for the ensuing year was presented, a; follows: Chairman. G.C. F. MacKenzie; vice-chairmen, C.S. Robinson, J. T. MacKenzzie, C. E. Meissner; executive committee, A. L. Field, R. F. Harrington, E. F. Kenney lit. Waterhouse announced that the fall meeting will be devoted to alloy steel. This meeting will be held in Chicago the week of Sept. 22 in connection with the National Metal Congress. He also announced that oxygen in steel will be the central idea of the meeting which will be held in New York next February. The first paper, entitled "Sintering Limonitic Iron Ore at Ironton, Minn.," was presented by Perry G. Harrison (T. P. 284), the author. Sintering was first un¬dertaken in 1024 to treat Cuyuna range iron and manganiferous ores low in silica and high in moisture and containing objectionable qualities of fine... A Dwight-Lloyd machine was first installed. This machine was replaced by a larger one having a width of 72 in. The power cost was decreased from about $11.22 per ton of sinter on a 42-in. machine to about X0.14 for the 72-in. machine. The tons of sinter per man-shift was increased from 11.86 to 16.77. Improvements embodied in the larger plant reduced the cost of sintering to $0.41. The analyses of iron ore and manganiferous ore and the sinter produced from these materials was used to show the increase in value at the mine resulting from sintering. Crude iron ore actually unsalable was increased in value f.o.b. mine from a theoretical figure

Jan 1, 1930

By J. Fogarty, J. Sofra

The mobile telecommunications sector is one of the fastest growing industries worldwide. However, increasingly stringent environmental regulations are placing pressure on manufacturers to accept responsibility for end of life products. The companies are therefore exploring avenues to recover the valuable components contained within the mobile telecommunications devices thus reducing the quantities of toxic components going to landfill. Batteries used to power the devices, are typically based on either nickel-cadmium, nickel metal hydride, or lithium ion cells. They contain toxic metals including nickel, cadmium, lithium, potassium, lead, and cobalt in a complicated arrangement of battery cells surrounded by a metals then plastic casing. The Ausmelt Catalytic Waste Converter (CWC) for waste treatment and recycling is well suited to processing all three mobile phone battery types for the recovery of valuable metals in marketable products that can be recycled to industry without turning out harmful levels of toxic emissions. Ausmelt recently demonstrated the capabilities of its CWC by continuously processing 4.5 tonnes of nickel-cadmium batteries. Using Ausmelt's pilot plant facility in Australia, the nickel-cadmium batteries were processed to produce a nickel iron sulphide (matte), a cadmium fume and a final slag which satisfied CS toxicity leach test criteria and was safe f<~r disposal to landfill. This paper explores the commercial development of the Ausmelt CWC for treating each of the three battery types in light of (a) the outcomes of the recent demonstration, and (b) the current and expected future availability of batteries for processing.

Jan 1, 2000

By P Holtham, K Duffy, B, W Valery, E Tabosa, rade

Pre-concentration has potential to significantly improve Mineral Resource efficiency by removing gangue early in the process, before energy intensive and expensive comminution and fine processing. However, there are numerous options for pre-concentration and the performance and benefits of these are very case specific. To determine the best option for a particular deposit and to successfully integrate it into the overall mining and processing operations requires comprehensive evaluation. This needs to consider orebody suitability, technology capability and economic viability. The in-situ variability of a deposit and how it is influenced by mining methods and the liberation size of gangue are key factors which are generally not well understood. Geostatistical methods provide an insight into orebody variability, and the overall selection of any pre-concentration solution must be an integrated approach between geology, mining and processing. Many pre-concentration evaluations investigate the potential of just one option. Technology selection should start wide and may include: selective mining, pre-screening (with or without selective blasting), sorting (bulk and or particle), coarse gravity separation (e.g. jigging, DMS), coarse particle flotation, magnetic separation, etc. The upgrade performance of these processes is very ore specific and should be determined from testing, with detailed multi-component modelling used to determine the overall process performance. Many of these pre-concentration processes require significant ancillary equipment, feed preparation and materials handling. It is important to realistically estimate all costs to understand overall economics and select the best option. Some examples showing evaluation and comparison of pre-concentration options are presented in this paper. These include assessments of in-situ variability using geostatistical tools, process modelling of pre-concentration options and overall performance, preliminary layouts and cost estimates, and economic evaluations.

Nov 10, 2020

By Surendra K. Mishra

With increasing regulatory pressure from the environmental authorities, waste management has become a focal point of industrial operation. To offset the waste management costs, industry has made conscious effort to recover usable resources from the waste streams. This paper reviews the technical developments and current practices in processing of waste materials. Methods for recovering metallic, non-metallic and organic species from solid wastes and effluents generated by operating plants are discussed.

Jan 1, 1997

By G. W. Healy, L. F. Sander

was investigated by reacting thin discs of calcium oxide with gas mixtures of CO2, CO, and Son. Its value was 19,300 * 300 cal independent of temperature in this range. No solid solubility of sulfur in calcium oxide was detected within the limits of the experimental method and it is estimated to be below 0.025 pct by weight. The importance of lime in desulfurization is well-established but complete information on the pure phase equilibrium: CaO + 1/2 s2 = CaS + +02 [11 is not yet available. The goal of this work was to evaluate solid solubility of CaS in CaO and to determine the free-energy change associated with Reaction [I] at temperatures of 1400" to 1650°C. The equilibrium constant for Reaction [1] can be written: It is convenient to rewrite Eq. [2] in the form: where A = {Ps /PqJ1&apos;2 has been referred to&apos; as the "sulfurizing power&apos; of a gas mixture. In this work, thin discs of CaO were suspended in a vertical tube furnace and exposed to CO + CO2 + SOz gas mixtures having known values of A. The samples were then analyzed for sulfur. As expected, X-ray diffraction confirmed that CaS was the only sulfur-bearing phase formed at the relatively low oxygen pressures used. EXPERIMENTAL PROCEDURE Reagent-grade CaCO3 was pressed in a 3/8-in.-diam pill die and prefired in air to produce CaO discs weighing between 0.004 and 0.01 g. Several discs were used to provide a suitable weight for chemical analysis while maintaining a large surface area to react with gas mixtures. These were placed in a platinum mesh basket and suspended in the gas stream in the hot zone of a vertical tube furnace. Desired gas mixtures were prepared from cp grade CO and CO2 and anhydrous grade SO2. The method of soap bubble displacement was used to calibrate capillary flow meters. While this gave excellent results with CO and Con, some problems with bubble insta- bility and soap film "drag" arose with the use of SO2 at low flow rates. Hence, frequent sampling and analysis of gas mixtures was carried out to insure proper control of the ingoing SOZ. The furnace used for gas:solid equilibration was a vertical mullite tube externally wound with 60 pct Pt-40 pct Rh wire having a diameter of 0.028 in. An inner tube of $ in. ID served as the reaction chamber having Pyrex ground joints sealed to the mullite to provide gas-tight connections at top and bottom. A Pt-Pt 10 pct Rh thermocouple was inserted into a protection tube adjacent to the sample basket to measure sample temperature during a run. Constant-temperature control to 2C was observed at any desired set point within the range of this investigation. This was accomplished by a control thermocouple imbedded in the furnace windings which served to actuate an electronic controller wired for high-low operation. The sulfur analyses of the solid samples were carried out using a stoichiometric combustion technique based on the method of Fincham and Richardson. Some analyses were done using a modified evolution method3 but these were used primarily to check the results of the combustion method. The results were in good agreement but the combustion technique of-ferred an advantage in economy of time and material. CALCULATION OF GAS EQUILIBRIA Heating a given mixture of CO + CO + SO2 to high temperatures gives rise to a large number of product species. The details of calculating the partial pressures of these products of interaction and dissociation can be found in several references4,5 and need not be repeated here. The thermodynamic data selected for the major species in the gas mixtures are shown in Table I. Equilibrium constants from these reactions were combined with oxygen, carbon, and sulfur balances and a computer program written to facilitate the calculations. Some early difficulties in reproducing experimental results were finally traced to the effect of atmospheric pressure changes. No reference to consideration of this question had been found in the

Jan 1, 1969

By J. R. MacDonald

MINING literature contains very few descriptions of operations producing as little as 25 to 30 tons of ore per day. The purpose of this paper is to discuss the gradual development of a mining method for such a small-scale operation at the No. 2 mine of Central Patricia Gold Mines, Limited, and in doing so to review several systems of stoping applicable to narrow ve1ns. MAIN ECONOMIC FACTORS TO BE CONSIDERED (1) Overhead.-The outstanding feature of most mines operating on a single narrow vein is chat of small daily tonnage. The reason for this low output can be readily understood. The strictly limited ore-reserves present a condition unfavourable for a policy of large initial expenditures, with the result that the capacity of the plant provided must be governed by the? amount of ore in sight at the time when mill construction is planned. This is immediately reflected in the cost per ton, there being relatively few tons over which to distributed the more or less static charges, such as hoisting, heating, supervision, administration, pre-production expenses, and other write-offs. (2) Development.-In mining this type of orebody, the main factor contributing to high costs is unquestionably the small tonnage of ore made available by a given amount of development. Thus, for example, from the data tabulated below it can be seen chat, assuming a 12-in. vein and a drifting cost of $9.00 per foot, the development charge for this item alone would be 71 cents per ton. Add to this the charges for raising, cross-cutting, shaft-sinking, and pumping, besides charges arising from development in waste, and the figure will be very considerably higher than 71 cents.

Jan 1, 1941

"The mining industry suffers from a number of incorrect perceptions, one of which is that it is an outdated industry that has not changed for hundreds of years. But the truth of the matter is that mining is a vibrant, highly complex industry that not only employs highly skilled and educated professionals but is also often on the cutting edge of technology. It is an industry with projects that are ever-evolving and among the most challenging engineering feats in the world.Take for instance the U.S. 53 Highway Relocation project in Virginia, MN. While more of a civil engineering job than a traditional mining project, it is still a complex engineering challenge taking place in a mining environment that has called on the skills of eight state agencies, three federal agencies, a host of contractors and many consultants, including many from the local mining industry in the Iron Range of Minnesota.In 1960, the Minnesota Department of Transportation (MnDOT) constructed U.S, Highway 53 on a private easement owned by US Steel that cut across a massive taconite deposit. MnDOT constructed the highway with the agreement that if the highway needed to be moved to access the taconite deposit before 1987, US Steel would foot the bill. And if the move was required after 1987, the responsibility would fall to MnDOT. In 2010, MnDOT received the notice that the highway would have to move as property owner United Taconite planned to access the ore, setting in motion one of the greatest engineering challenges, and the highest risk project, in the history of the states’ transportation department.Pat Huston, U.S. Highway 53 Relocation project manager, opened the 90th SME Minnesota Section Conference in Duluth, MN on April 19 with a presentation about the project that includes 5 km (3.2 miles) of fourlane highway and a new 345-m (1,132-ft) bridge that will be the tallest in Minnesota when it is completed later this year.“This project was not business as usual,” Huston told the packed crowd. “Highway 53 connects Canada and the Iron Range to Duluth and Lake Superior. It is an important highway.”During his presentation he spoke about many topics that were familiar to the more than 1,100 mining professionals who attended the conference. In his keynote speech,"

Jan 6, 2017

By I. M. Roberts

THE war emergency has affected every phase of industry. The gas and coke-oven companies have sought faithfully to discharge their responsibility in this critical period and have willingly modified their operations where possible to meet the ever increasing demands made upon them. Our company made commitments for blast-furnace coke for war purposes which necessitated a reduction in coking time in order to produce the amount required to. meet the new demands. At the same time there were certain customers of long standing, who had been supplied with foundry and egg-sized coke produced on fairly long coking periods, who also were engaged in war work and whose patronage we desired to retain. Coke produced on short coking rates from the coal mixture we were then using would not have been satisfactory for these customers. The average width of our ovens is 19 ¾ in., which is a little wider than the more modern ovens of the present day. They were originally designed to give somewhat cool tops in order to produce a rich gas. This necessitates carrying the heats a little on the warm side so that the tops will be fully carbonized. A reduction in coking time, as is generally known, is accompanied by a reduction in the average size of the coke produced. This is due to the greater shrinkage that takes place at the higher temperatures required to carbonize the charges in a shorter time. The net result is that the coke is more cross fractured and longitudinally fractured and breaks up into small sizes on handling. The cokes produced from the better coking coals seem to be more susceptible to fracture at high temperatures than those from poorer coking coals. A coal mixture that produces a beautiful foundry-sized coke at 30 to 36 hr. may yield a product at 18 hr. that would be so badly fractured as to be unsatisfactory for foundry practice. COKING CHARACTERISTICS OF COALS Our problem was to find some economical innovation and develop a method that would enable us to reduce the coking time and still produce a coke satisfactory to our foundry trade. However, before discussing the results of our present operations, it might be well to present a few observations on the coking characteristics of coals in general. Most coke-oven operators carbonize a blended mixture of coals. It may consist of a single high-volatile coal with a single low-volatile coal, or of a combination of several high-volatile and low-volatile coals. Medium-volatile coals of the Eagle seam are used for the production of high-grade foundry coke. Medium and high-volatile coals are often blended with one or more low-volatile coals. The possibilities are almost infinite, but the combinations are limited by such factors as cost and facilities for handling multicoal mixtures, and by other practical considerations. Every coal has characteristics that make it blend better with a particular coal or coals in preference to others. This property has

Jan 1, 1944

By R Schiller, E Chait

"Quebrada Blanca is a porphyry copper deposit located in the Eocene-Oligocene belt of Chilean Andes. Operation started in 1994 and original reserves for supergene mineralisation gave a life-of-mine (LOM) of 20 years; however, further exploration extended the LOM until 2020.In order to optimise the remaining five years of supergene resource, geometallurgical variables were added to the geological model including copper recovery and acid consumption. LOM plan encompasses finishing the phase number eight and the future development of phases 11 and 13.LOM lithologies include diorites, quartz monzonites, porphyries, igneous and tourmaline breccias. Main alterations are: potassic, phyllic and argillic. Litho-alterations or geometallurgical units were formed by combining five types of rocks with three types of alteration. According to statistical information, the deposit can be represented with 12 litho-alteration units, which cover 98 per cent of the LOM volume.For copper recovery information, there were 40 mini-columns tests made in order to obtain kinetics curves and copper recovery values after comparing the difference between head and tails grades. Acid consumption was obtained using an automatic neutraliser device-based test.Historical data said that copper recovery in pads after 450 days of irrigation is around 75 per cent of recoverable copper while acid consumption is around 5.5 kg/t.According to this study, lower recoveries are related with potassic-altered diorites and argillic-altered quartz monzonites with values around 60 per cent. On the other hand, best recoveries could be found in potassic-altered quartz monzonites and argillic-altered diorites with values closer to 80 per cent.It was also revealed that the most reactive rock is the potassic-altered diorite with 12 kg/t of acid consumption. This rock covers approximately 40 per cent from phases 11 and 13.The final geomet model was calculated using a program that relates each geometallurgical unit with a specific copper recovery and acid consumption value. Results found after comparing model-obtained information with historical leached pads data were used to validate the model.CITATION:Chait, E and Schiller, R, 2016. Adding Copper Recovery and Acid Consumption Variables to the Geological Model of Quebrada Blanca, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 257–266 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By Eric Barnard, Andreas Nashitati, John Tero, Guy Deschênes, Setta Mbalamba, John Rajala

The Otjikoto Mine, owned at 90% by B2Gold Corporation, is located 300 km north of Namibia’s capital city of Windhoek. The reserves from the open pit mine, estimated at 25.9 million tons with an average grade of 1.28 g/t Au, contain gangue minerals, pyrite and pyrrhotite, and have an estimated 10 year mine life. The feasibility study included an optimisation of gold leaching using CSTR for the original design. The results of the test work were used to establish the design criteria. Gravity tails from three composites (drill cores), representing the major ore types, were used. The XR3 sample (gravity tails) contained 0.32 g/t Au, while the XR2 and XR1 gravity tails samples (used for variability) contained, respectively, 0.30 g/t Au, and 0.47 g/t Au. The optimum leaching conditions were: a pre-treatment of 7 h at pH 10.5 with 100 g/t lead nitrate, DO > 5 ppm followed by cyanidation at 300 ppm NaCN, pH 10.0, DO > 5 ppm for 48 h. The gold extraction was 91.5% (97.2% overall extraction gravity/leach) and the cyanide addition was 0.57 kg/t NaCN. Increasing the DO to 16 ppm did not show any economic benefits. No pre-treatment or a 4-h pre-treatment reduced the gold leaching kinetics. The XR2 and XR1 gravity tails samples had gold extractions of 92.9% and 92.3%, respectively. At the plant scale, an 11 h pre-treatment is used followed by 42 h cyanidation with 250 ppm NaCN and an average DO of 8 ppm and 230 g/t lead nitrate in 2016. The cyanide addition was 0.49 kg/t NaCN. The commercial operation started on February 28th, 2015. The overall gold recovery and production were 98.4% and 145,696 ounces for 2015 and 98.1% and 166,286 ounces for 2016. It was found that retention times, gold content of leach residues and cyanide addition are comparable for the lab and the plant. Details of the Otjikoto process flowsheet are discussed in this paper along with the results of the lab leach optimisation test program and the plant leach circuit performance and improvements.

Jan 1, 2017