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By John L. Bolles

The Phelps Dodge Corporation's Morenci Concentrator includes facilities for coarse crushing, fine crushing, grinding, flotation, tailing, disposal, concentrate filtering, and drying. The Morenci Concentrator daily throughput is in excess of 60, 000 tons. The ore milled is mainly a medium-hard monzonite porphyry in which the principal sulfide minerals are chalcocite and pyrite. The ore is transported by rail from the Open Pit Mine to the primary crushing plant located at the concentrator site. Ore is side-dumped from 80¬ton railroad cars into a sixty-inch gyratory crusher. The ore is then conveyed to a. 12, 000 ton coarse ore storage bin. Fine crushing is accomplished by four parallel lines of conventionally stacked crushers in open circuit. Each unit consists of one seven-foot standard cone followed by two seven-foot shortheads. Ti% product of the fine crushing plant is distributed by two tripper cars across a fine ore storage bin. The crushed ore is then fed by variable speed belt feeders into thirty parallel, single stage, closed circuit grinding units. Each of the 30 grinding units consists of one 6' x 23' conditioning drum, one 10' x 10' ha l mill and two 54" duplex spiral classifiers as principal equipment. The dry ore is fed into the conditioning drum with water to dilute the ore to a slurry of approximately 78% solids by weight. An aqueous solution of ammonium sulfide is also added to the conditioning drum. The ammonium sulfide primarily acts as a sulfidizing agent. The ore slurry containing the naturally occurring sulfide copper minerals and the sulfidized copper minerals discharges into the feed scoop box of the ball mill, where milk of lime, collector and-.dilution water are added. The ball mill product slurry is gravity fed: to the classifier pool where water is added to obtain the desired classifier overflow product

Jan 1, 1977

By M. R. Hieb, J. R. Britt, S. P. Harteis, M. J. Sapko, E. S. Weiss, R. K. Zipf

The design requirements for mine ventilation seals have undergone a radical transformation in recent years, and these revisions have greatly increased the cost of the seal designs and their construction. For example, in the past two years, new federal regulations have increased the minimum design requirement to withstand explosion pressures from 138 kPa (20 psig) to 345 kPa (50 psig) or 827 kPa (120 psig), depending on whether the sealed mine volume is monitored continuously or not. Moreover, there is still a possibility that under certain conditions (such as detonations), even higher pressure requirements may be necessary. The ability of a monolithic, stand-alone mine seal to reliably withstand the full range of possible explosion pressures is becoming increasingly difficult and expensive. In an effort to develop a practical alternative, the West Virginia Office of Miners’ Health Safety and Training (WVOMHST) and the National Institute for Occupational Safety and Health (NIOSH) have collaborated in a research effort to develop a practical, economic and safe mine sealing technique that can enable mine seals to meet the full range of new explosion pressure design requirements. The basic idea is to use a barrier of common mine gob and rubble, in combination with a conventional mine seal, so that the pressure resulting from a gas explosion is reflected, absorbed and attenuated, and the pressure on the ventilation seal is reduced. This paper discusses some concepts and preliminary test results for a “passive mine blast attenuator” (PMBA) that can provide a useful alternative to increasingly larger and stronger stand-alone mine seals. Numerical models and full-scale experiments conducted at the NIOSH Lake Lynn Laboratory Experimental Mine (LLEM) show that the use of a PMBA can signficantly reduce the blast pressure and impulse on conventional ventilation seals.

Jan 1, 2009

By Stephen Semeniuk

Working with junior mining companies as a valuer, my experience with regulators is that simplicity works and the sales comparison method is the way to go. What I like about Mr. Ellis?s approach (as in his Table 7) is the integration of commodity prices with the timing of acquisitions and the implication of price changes in gold on the adjustment of individual project valuations. However, the sample gold-related appraisals in Ellis?s paper are pre-2008 transactions and readers should be made aware of the current market for such projects. Before moving on, to be noted is that the effective date of the Las Brisas appraisal (Ellis?s sample Appraisal 3) is Feb. 10, 2006; given that the subject value of Transaction 9, Choco 10 in Ellis?s Table 6 was listed as $353 million for a 95% interest in the con-cession, I am uncomfortable accepting that the acquisition was suddenly worth the adjusted value of $1,205 million (as given in Ellis?s Table 7). In some cases, illiquidity discounts can apply, and commodity-wise, in the one-month period between the acquisition in January 2006 and the adjustment to the Las Brisas conditions as of February 10, 2006, the indicated gold price change was only 41 cents/g ($12.60/oz); i.e., from $17.50/g to $17.91/g ($544.40/oz to $557/oz).

Jan 1, 2012

By Richard L. Bullock

Believe it or not, mine evaluation and feasibility studies are as old as the industry itself. In the first recorded writing on mining by Agricola (1556), he gave several clues as what to look for in evaluating a mine, to determine if it was economically feasible. Below is the guidance from Agricola, with my interpretation of what he would include today. Now a miner, before he begins to mine the orebodies must consider seven things, namely: ? The situation (the geography/topography). ? The conditions (the geologic/mineralogic and mining conditions). ? The water (availability, hydrology and ownership). ? The roads (plus the railroads, power lines, all other infrastructure). ? The climate (the weather-rainfall/environment). ? The right of ownership (the land and legal entitlement). ? The neighbors (the social environmental concerns of the area). It is amazing how much of his guidance has not changed in 455 years. Yet Agricola gives no guidance on determining the correct cost, or determining the correct commodity pricing. But he does give a few words of caution on the related ethics involved on buying mineral properties: ?A prudent owner, before he buys shares, ought to go to the mine and carefully examine the nature of the vein, for it is very important that he should be on his guard lest fraudulent sellers of shares should deceive him.? Three hundred years later (1866), to further amplify this point, in the most famous thing that Mark Twain never said, as an introduction to a lecturer to an audience of gold-miners at Red Dog, CA, the famed author/humorist allegedly described a mine as ?a hole in the ground owned by a liar? (Farrar & Rinehart, 1935). So, one might conclude that between these two dates, the mining industry did little to improve its reputation. Unfortunately, since Mark Twain allegedly made those remarks, we have not done near enough to gain accountability for the mineral industry.

Jan 1, 2011

By M. Misra

Improved liberation and flotation of kerogen from eastern oil shale were accomplished with high-temperature grinding and a1 so with the addition of fuel oil during the grinding stage. Liberation measurements indicated that possible coalescence and aggregation phenomenon of kerogen particles during grinding may reflect this behavior. Additionally, ultrasonic treatment of the rougher concentrate prior to cleaning improved the quality of separation.

Jan 1, 1984

By X. Tang, N. Ripepi

The Langmuir model has been widely used for the coal-methane sorption process through an isothermal test. However, even though the temperature-dependent Langmuir model was recognized theoretically and experimentally, the quantitative relationships between the Langmuir constants a and b and temperature have not been clarified and confirmed by laboratory test data. This paper collects 158 methane-coal sorption data under different temperatures that apply the Langmuir model to the relationships between the Langmuir constants a and b and temperature. Even though the Langmuir model cannot be used to show the physical state of methane adsorption on coal, it is widely used because of its simplicity and the reasonable explanation of its parameters a and b. The results from these published isothermal tests indicate that (1) there is no consistent relationship between Langmuir constant a and temperature, (2) the Langmuir model is a temperature-dependent model whose temperature-dependent feature is mainly shown by the relationship between the Langmuir constant b and temperature, and (3) the relationship between the Langmuir constant b and temperature can be described by both exponential and linear relationships with dried coal. This paper provides a database for the temperature-dependent Langmuir model that can be used for the reservoir simulation of coalbed methane reservoirs and for the coal seam degasification modeling of underground coal mines, considering the heating effects induced by geothermal and heat injection through factors such as hot water, hot steam and ultrasonics.

Jan 1, 2016

By D. Zim

Mining activity in South America is a growing enterprise. One of difficulties found in many areas of the South American continent, especially in north Chile and south Peru, is the shortage of water supply. In order to overcome this difficulty some mining companies proposed to transport the water from Pacific Ocean up to the mountains. This can be accomplished by the use of stainless steel pipelines, but this is a cost prohibitive solution and is also subject to severe pitting corrosion in a saline environment. The use of mild steel may be a lower cost solution than stainless steel as the material of construction for pipelines but it is subject to corrosion anyway. The corrosion in this case can be internal or external corrosion although cathodic protection as well preventive maintenance usually is enough to mitigate external corrosion without the need to shut down the pipeline. The same is not true about the prevention of internal corrosion. It is not practical, sometimes not even possible, shutdown a pipeline to carry out an inspection and fix sections where potential failures are detected. It is possible avoid corrosion caused by sea water within the mild steel pipelines by applying a proper chemical program designed to virtually eliminate dissolved oxygen in the water commonly called deaeration.1 This type of treatment obviously involves additional capital investment since it requires the construction of one deaerator with the first pumping station and additional equipment at each point where the water can come into contact with oxygen. Deaerators will increase operational costs and subsequent injection of chemicals will be required in the case of multiple degasification facilities thus increasing the consumption of chemicals. grams based on oxygen scavengers, the objective of the present study is to develop a new water treatment capable of preventing mild steel corrosion in aerated sea water. The new treatment must be able to prevent both generalized and localized (pitting) corrosion and overcome the necessity to construct and operate deaerators.

Feb 23, 2014

By Volkan Arslan

This study aimed to remove the contaminants in quartz sand by using an eco-friendly method and to obtain high-purity quartz. For this purpose, ultrasound-assisted acid leaching was applied. Equal amounts of a mixture of diluted hydrochloric and oxalic acids were used as the solvent. Response surface methodology (RSM) was used for optimizing, modeling, and predicting the experimental parameters. The correlation coefficient ( R2) of the proposed quadratic model for the relationship between iron removal yield and test parameters was calculated as 0.9731 and it was determined that the predicted and actual values were compatible. Finally, optimization experiments were made and optimum experiment conditions were revised and determined as 83.38 °C of leaching temperature, 196.35 min of leaching time, 2.86 M of acid concentration, and 202.24 W of ultrasound power. Under the optimum conditions determined after optimization, the highest yield of iron removal was determined as 95.08%. Under the optimal parameters, the SiO2 content of the concentrates increased from 97.841 to 99.907% and the Fe2O3 content reduced from 0.225 to 0.011%.

Jul 12, 2021

By Yves Picot

Construction of new installations was recently completed in the Port of Tubarao, Brazil, With this expansion the port, operated by Companhia Vale do Rio Doce (CVRD), has become the largest iron ore port in the world, with an annual throughput capacity of 60 million long tons. GROWTH OR IRON ORE EXPORTS Since its formation CVRD has steadily increased the shipment of iron ore to overseas markets. Starting with less than 100,000 tons in 1942, the yearly export volume grew to 1,500,000 tons in 1951, 5,000,000 tons in 1961 and 25,000,000 tons in 1971. The number of different grades of ore also increased during this period. Production of high grade pellets, starting in 1970, further increased the number of ore products to be shipped. In the same period the size of ore carriers increased twenty-fold to over 250,000 DWT.

Jan 1, 1974

By Drew A. Meyer

Magnetic metals are the granddaddy of products which may be recovered from municipal waste. Aside from hand-picking of newsprint and corrugated boxes, magnetic metals are usually the first items a resource recovery facility considers extracting from the solid waste stream. Magnetic metals from incinerator residues and from municipally mandated source segregation programs were first used in significant quantities by the Copper Industry. The ability of the Copper Industry to consume metals from the municipal solid waste stream raised everyone's hopes that there would be more markets for municipal scrap when more of it became available. Somehow something has gone wrong. It is widely acclaimed that scrap is an environmentally sound and economical source of iron. It is greatly in demand for Its contained energy. The prices that the steel industry has been willing to pay for the scrap during the past year are all the proof anyone should need that scrap Is desirable and sought after. But the very fact that I'm speaking today on the markets for magnetic metals recovered from municipal waste indicates that something Is wrong. Clearly the problem is not that we do not need the scrap. The problem is we have not produced the kind of scrap that consumers are willing to buy - either through ignorance of what the consumers wanted or through a conviction that ferrous scrap is so obviously a good thing somebody will surely want it no matter what. Dr. Harvey Alter of the National Center for Resource Recovery has said "You can't sell garbage". In a sense that is only partly true. It really should be "You can't sell garbage for very long". The Steel Companies, in an effort to prove that steel is an environmentally desirable packaging medium, have bought some scrap that can only be described as garbage. They are to be commended for doing so. The fault lies not with the Steel Company for taking and paying for "garbage" but with the producer of that poorly prepared scrap. Far every instance where the steel industry has purchased the often undesirable product from resource recovery facility there are several magnetic installations sitting Idle because someone forgot the most essential part of producing the magnetic product - selling it to someone.

Jan 1, 1975

By Richard S. Klein

Frozen coal creates severe handling problems. Utilities require uninterrupted supplies of coal to meet their increasing coal consumption rates. Difficulties incurred due to frozen coal result in more costly downtime for the utilities. Air cannons, vibratory hammers and thaw sheds are examples of mechanical devices used to break, crack or thaw frozen coal. Recently chemical treatments have been developed as preventive measures. The freezing of coal depends upon a number of factors, of which one of the most significant is surface moisture. The more there is, the larger the frozen coal problem. Slide 1 depicts a graph of frozen coal compressive strength as a function of surface moisture. Below a certain minimum value the coal will not freeze. Above this point, compressive strength is essentially a linear function of moisture over the range practically encountered. By surface moisture is meant the free moisture on coal having a normal vapor pressure as opposed to capillary moisture or inherent moisture. In addition to the straightforward freezing of coal surface moisture binding particulates together, frost formation occurs due to temperature gradients which develop in rail-cars and stockpiles .

Jan 1, 1980

By F. J. Sotillo

The objective of this investigation was to determine the feasibility of using a high-pressure roll mill (HPRM) to improve the separation efficiency of dolomite from apatite in downstream operations when treating high-dolomitic pebbles. High-dolomite samples from four phosphate mines were used for the test program. The research work plan included sample characterization studies; INSTRON tests to develop preliminary crushing data; high-pressure roll mill evaluations to determine crushing parameters, such as feed rates, rolls speed and gap, and applied torque, pressure and energy; and screen, microscopy, and flotation studies to assess dolomitelapatite separation efficiency. The results of the HPRM tests show that commercial products for all four mines can be obtained. Recoveries of 74-82% of the P2O5 and rejections of 46-83% of the MgO were reported with an specific energy consumption of 0.2-0.5 of that of a laboratory rod mill.

Jan 1, 1998

By James F. McConnell

Federal and State sulfur oxide emission and ambient air quality regulations have been implemented to fulfill the requirements of the Federal Clean Air Act Amendments of 1970. Primary and secondary air quality standards have been established at levels considered necessary to assure the protection of the health and welfare of the public. Standards of performance under this Act have been established to control the rate of sulfur oxide emissions from individual sources so as to protect and to improve the quality of the Nation's air. The new source standards of performance were made rigorous for large coal burning stationary sources. This has had a severe impact on the electric utilities that operate the coal fired steam electric plants which are the largest consumers of the Nation's coal production. States have taken different approaches in State Implementation Plans (SIPS) as approved by the Federal Environmental Protection Agency. Some states, such as Pennsylvania, have chosen to permit moderate SO2 emission rates from existing sources which are not in critical air basins. All are required to meet primary and secondary air quality standards and to limit sulfur oxide emissions from new large stationary sources to a minimum of 1.2 LBS of S02/MMBTU fired. This re- quires a fuel sulfur percentage of about 0.7 for a 12,000 BTU/lb coal. In an effort to develop strategies and technologies to conform to performance standards while continuing and hopefully expanding the utilization of the Nation's coal supply, the electric utilities, the Federal and State regulatory agencies, and other industries and government agencies are considering several alternatives. 1. Natural low sulfur coal 2. Flue gas desulfurization - (FGD) non-regenerative and regenerative 3. Coal gasification 4. Liquefaction and solvent refined coal 5. Fluidized bed combustion 6. Chemical coal cleaning 7. Physical coal cleaning Of these options, only the first and the last can be considered to be widely used in full commercial practice at this time. FGD has certainly demonstrated technical and operating feasibility and is close to being in full commercial practice but it remains to be seen if the large systems under construction are economically and environmentally optimum.

Jan 1, 1975

By Albert J. Shohet

The increasing scarcity of bentonite coupled with the potential of improved pellet strength have created a need for understanding the effects of thorough bentonite dispersion in taconite concentrate. It has been known for more than a decade that under certain conditions substantial savings of bentonite are realizable by using thorough mixing of bentonite as compared to poor mixing. Extensive work done by J. O. Zetterstrom l at the Univer¬sity of Minnesota indicated the effect of thorough bentonite mixing in a controlled laboratory testing. Commercial hardware was not available at the time Zetterstrom1 paper was published and not much work was done until R. L. Stone, J. M. Karpinsky2, did work with Muller mixing. Nabush 3 worked with the pugmill principle, and Hoogovens 4 and Robe River 5 used the fluidized bed principle. It was very hard to convince iron ore industries to improve the mixing of Bentonite and taconite for the following reasons: A. The initial capital investment for improved mixing equipment; B. The relatively low bentonite cost a few years back, which was not enough to justify new equip¬ment investment;

Jan 1, 1976

By M. Scaggs, L. R. Mendoza

"On January 9, 2014, a large chemical spill occurred on the bank of the Elk River near Charleston, WV. Within hours, the potable water supply for more than 300,000 people was contaminated, and the incident captured national headlines for weeks. Although the primary chemical, crude 4-methylcyclohexanemethanol, or MCHM, is deemed nonhazardous, the impacts of the spill are significant – with all stakeholders, including the public, members of industry, and relevant government agencies experiencing losses. This case highlights the need for a more proactive approach to environmental management, shifting from crisis control and remediation to crisis prevention and risk management. INTRODUCTION On the morning of January 9, 2014, approximately 10,000 gallons of crude 4-methylcyclohexanemethanol (MCHM) leaked from a 48,000-gallon storage tank sitting on the bank of the Elk River near Charleston, West Virginia (WVDEP, 2014; CSB, 2014). MCHM is a chemical commonly used in preparation of fine coal, and is deemed nonhazardous in terms of transportation and storage regulations and also toxicity (CDC, 2014a). Freedom Industries, Inc., a producer and vendor of specialty chemical products, had acquired the storage facility where the spill occurred from Etowah River Terminal, LLC just a few weeks prior in December 2013 (WVDEP, 2014; Freedom, 2005). The direct cause of the spill was ultimately determined to be two small holes in the base of the 76-year-old tank, which were created due to corrosion damage (Bauerlein & McWhirter, 2014). The spill site was located just over a mile upstream from the intake of a municipal water treatment facility operated by West Virginia American Water (WVAW), which serves a population of 300,000 across nine counties in central West Virginia (CDC, 2014a). In a matter of hours, the leaked MCHM made its way through the treatment facility and into the water of nearby homes and businesses, where its strong smell was noticed almost immediately. On the evening of the spill, WVAW concluded that its conventional treatment processes, which include carbon filters to remove a variety of contaminants from water, were not capable of fully removing the MCHM and a “Do Not Use” order was issued for all customers (WVAW, 2014a). With little information readily available regarding the potential human health effects of MCHM, the US Centers for Disease Control and Prevention (CDC) quickly issued an advisory ruling that set a maximum screening level of 1 ppm for safe drinking water (CDC, 2014a). Based on this recommendation, the “Do Not Use” order remained in effect for a total of eight days, until January 17, when the WVAW distribution water was confirmed to have MCHM concentrations below this level (WVAW, 2014a). However, due to the pungent odor of the chemical, its presence was still recognizable in the WVAW facility and in consumers’ tap water after the order was lifted (Manuel, 2014). Recent studies have shown that the chemical can be detected in water at concentrations as low as 0.55 ppb by individuals experienced in odor identification (Rosen et al., 2014); and even individuals with no such training can detect pure MCHM at just 7 ppb (WVTAP, 2014). The fact that this chemical can be sensed at such low levels – indeed far below those considered safe – undoubtedly added to growing public concern. In response to numerous complaints and demands, WVAW continued flushing the treatment facility and pipes until February 25 when MCHM levels were measured below 2 ppb (WVAWb, 2014), and eventually replaced the affected filter media (WVAWc, 2014)."

Jan 1, 2015

By T. R. Kostecki, A. J. S. Spearing, G. S. Esterhuizen, K. V. Jessu

Discontinuities are geologic occurrences in rock and when present within a pillar, reduce the strength of the pillar. Empirical formulas that are commonly used to determine pillar strength do not explicitly take into account the presence of discontinuities and thus can overestimate the pillar strength. The effect of discontinuities on the strength of pillars has been investigated using numerical models, but in these models, the discontinuity strike was parallel with the pillar faces. In this study, fully three-dimensional hard rock pillars were simulated using numerical modeling to understand the effect of the discontinuity dip direction on square and rectangular hard rock pillars. Based on the results, recommendations to assess a pillar’s strength in the presence of a discontinuity are discussed.

Jan 1, 2018

By SUHAINA ISMAIL, NORLIA BAHARUN, SHAIK ABDUL RAHMAN, WAN NUR SYAFIQAH ANUAR, MOHAMMAD REZAEI ARDANI

Hypochlorite leaching system is a strong oxidizing solution for metal sulfides, which are naturally associated with gold extraction. This study evaluated the hypochlorite leaching of refractory gold ore by using the response surface method–central composite design (RSM-CCD) as a statistical approach in determining the optimum condition of gold extraction from refractory gold ore. The studied parameters for the gold recovery were pH (4 to 6), concentrations of Ca(OCl)2 (0.5 to 1.5 M) and NaCl (2.5 to 3.5 M) in the solution. It was found that the maximum gold extraction of 82.46% (13.85 g/t) was achieved at a pH of 4.0 with NaCl and Ca(OCl)2 concentrations of 2.93 M and 1.08 M, respectively. The statistical analysis also revealed that the amount of gold recovery in chloride solution was significantly depended on pH as the main factor, followed by concentrations of Ca(OCl)2 and NaCl.

Jan 8, 2021

By Moussa Wone, Jeff Peterson, Filippo Azzarà, Daniele Nebbia

The DC Water and Sewer Authority's Long Term Control Plan includes tunnels, sewer separation, pumping station rehabilitation and green infrastructure to reduce combined sewer overflow (CSO) discharges to the District waterways. The Northeast Boundary Tunnel is a deep, large sewer tunnel that will reduce CSO discharges; signifi- cantly mitigate known chronic flooding in the Northeast Boundary drainage area and improve the water quality of the Anacostia River. This paper presents the unique combination of Owner and Contractor perspectives of the entire Project from conception through procurement, execution, and contract management, providing lesson learned, chal- lenges encountered, and solutions implemented to deliver the Project successfully.

Jun 23, 2024

By Michael Murphy, Gamal Rashed, Brent Slaker

Pillar stability continues to be a significant concern in multiple-level mining conditions, particularly for deep mines when pillars are not stacked or the thickness of interburden between mining levels is thin. The National Institute for Occupational Safety and Health (NIOSH) is currently conducting research to investigate the stability of pillars in multiple-level limestone mines. In this study, FLAC3D models were created to investigate the effect of interburden thickness, the degree of pillar offset between mining levels, and in situ stress conditions on pillar stability at various depths of cover. The FLAC3D models were validated through in situ monitoring that was conducted at a multiple-level stone mine. The critical interburden thickness required to minimize the interaction between the mining levels on top-level pillar stability was explored, where the top level mine was developed first followed by the bottom level mine. The model results showed that there is an interaction between numerous factors that control the stability of pillars in multiple- level conditions. A combination of these factors may lead to various degrees of pillar instabilities. The highest degree of local pillar instability occurred when pillar overlap ranges between 10 and 70%. On the contrary, the highest degree of stability occurs when the pillars are stacked, the underlying assumption is that the interburden between mining levels is elastic (never fails). Generally, for depths of cover investigated in this study, the stability of top-level pillars shallower than 100 m (328 ft) or with interburden thicknesses greater than 1.33 times the roof span—16 m (52.4 ft) in this study—does not appear significantly impacted by pillar offset. The results of this study improve understanding of multiple-level interactions and advances the ultimate goal of reducing the risk of pillar instability in underground stone mines.

Jul 27, 2022

By Ali Jaberi Zamharir, Abolfazl Shoghian‐Alanaghi, Hossein Aghajani, Arvin Taghizadeh Tabrizi

In this study, the leaching rate of molybdenite concentrate was evaluated in sulfuric medium, and the influence of the diverse oxidants including hydrogen peroxide, manganese oxide, copper sulfate on the leaching rate was studied. Also, the effect of the addition of the ethylene glycol to the hydrogen peroxide was studied and results showed that with the addition of ethylene glycol, the leaching rate is increased 55% from 41% up to 80.3%. The optimum condition is achieved as 0.7 M of H2SO4, 4.4 M of H2O2, and 3.5 M of EG at 30 °C within 4 h of leaching time and 500 rpm. Also, inserting the oxygen with the pressure of 6 bar to the leaching autoclave, the leaching rate is increased more up to 86.4%. Finally, the leaching process was studied kinetically and the determined mode of controlling factor was specified based on the activation energy which equals 46.252 kJ/mole indicating the chemical reaction mode.

Jun 5, 2022