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By D. Scott Scovira, Remi Proulx

The Meikle Mine is a high grade, underground gold mine utilizing primary-secondary longhole open stoping with delayed backfill to produce 3000 stpd of ore. Hot and reactive ground conditions were encountered early on in the mine life. Ground temperatures up to 330” F were measured. In the early stages of mining, the mine experienced premature detonations using different explosives. The learning curve to safely mine this high-grade gold deposit in hot and severely reactive ground was indeed very steep. Currently, the Meikle Mine uses a special buffered bulk emulsion in all blasts to address hot and reactive ground concerns. In addition, exacting procedures are also followed to ensure safe work with explosives. The combination of new explosives technology and strict loading procedures permits high mine productivity with the highest degree of safety.

Jan 1, 2000

By A. S. Richardson

Ventilation of the Butte mines has long been a rather difficult problem because of the natural high temperature of the rock. With increase* in mining depth, higher rock temperatures have been encountered, and this has caused a constantly growing demand for more effective ventilation measures. During recent years the hazards of dust in mine air have been more clearly recognized, and have necessitated the adoption of dust-prevention methods. To meet these ventilation problems in the mines of the Anaconda Copper Mining Co., a mines ventilation department was organized in 1918, to act under the direction of the general superintendent of mines. At the present time, under normal operating conditions, the force employed includes the ventilation engineer, two chief assistant ventilation engineers and eight assistant ventilation engineers. The activities of the department are, briefly: (1) planning and supervising operation of the general ventilation system; (2) planning and supervising the operation of dust-prevention measures, together with dust sampling and related microscopic work for the quantitation of the dust samples and determination of particle-size distribution; (3) the design and development of air-conditioning methods to meet present exceptionally severe temperature conditions and in anticipation of future requirements. To a large extent the technical features of the ventilation methods have been described in earlier papers by the author. This paper is written mainly to summarize past accomplishments bearing most closely on health and safety, with a somewhat more detailed account of the dust-prevention measures that have been developed comparatively recently. Facilitating Flow of Am As a basic requirement for the safety of the mcn, all ventilation plans are subject to a ruling that the main operating shafts must be maintained as inlet air courses. Under this condition, a safe, fresh-air escapeway is assured if a fire occurs within the mine, and the shaft; is available as a base

Jan 1, 1940

By A. S. Richardson

Ventilation of the Butte mines has long been a rather difficult problem because of the natural high temperature of the rock. With increase* in mining depth, higher rock temperatures have been encountered, and this has caused a constantly growing demand for more effective ventilation measures. During recent years the hazards of dust in mine air have been more clearly recognized, and have necessitated the adoption of dust-prevention methods. To meet these ventilation problems in the mines of the Anaconda Copper Mining Co., a mines ventilation department was organized in 1918, to act under the direction of the general superintendent of mines. At the present time, under normal operating conditions, the force employed includes the ventilation engineer, two chief assistant ventilation engineers and eight assistant ventilation engineers. The activities of the department are, briefly: (1) planning and supervising operation of the general ventilation system; (2) planning and supervising the operation of dust-prevention measures, together with dust sampling and related microscopic work for the quantitation of the dust samples and determination of particle-size distribution; (3) the design and development of air-conditioning methods to meet present exceptionally severe temperature conditions and in anticipation of future requirements. To a large extent the technical features of the ventilation methods have been described in earlier papers by the author. This paper is written mainly to summarize past accomplishments bearing most closely on health and safety, with a somewhat more detailed account of the dust-prevention measures that have been developed comparatively recently. Facilitating Flow of Am As a basic requirement for the safety of the mcn, all ventilation plans are subject to a ruling that the main operating shafts must be maintained as inlet air courses. Under this condition, a safe, fresh-air escapeway is assured if a fire occurs within the mine, and the shaft; is available as a base

Jan 1, 1940

By J. B. Hiskey

Introduction The domestic copper industry has suffered for some time from declining ore grades; rising costs associated with conventional mining, milling, smelting and refining; tightening environmental restrictions; and shrinking markets due to materials substitution. Ore grade depletion is a major problem. It is illustrated by the decline in average copper yield shown in Fig. 1. From 1979, copper grade has dropped 60%, lowering yields from 1.2% to 0.49% (Sousa, 1981). The US copper industry is taking drastic measures to enhance its competitive posture and to guarantee its future worldwide position. In a sense, this involves a general restructuring of the processing philosophy of US copper producers. Judging from recent trends, this restructuring relates to the application of solution mining techniques to the treatment of copper ores and low grade waste material. Recovering copper by leaching techniques has been practiced for centuries. As early as the mid-16th century, some Hungarian copper mines were recycling copper bearing leach solutions through waste heaps (Nash, 1912). In the US, recovering copper from dilute mine waters has been carried out for more than 100 years. There are, however, certain technical innovations that have elevated the importance of solution mining as a process for copper recovery. These include: • Advances in solvent extract-electrowinning (SX-EW); • Developments in acid and acid ferric cure processes for oxide and mixed oxide sulfide ores; • Improvements in heap and dump construction; and • Advances in in situ leaching technology. Generally, solution mining enjoys certain intrinsic advantages over conventional mining and milling. Compared to conventional milling, the combined capital and operating costs of leaching facilities are normally lower, start-up times are faster, and the leaching operation usually has less impact on the environment. Furthermore, solution mining represents an expedient way of extracting metals from small shallow deposits, and is particularly suited to the treatment of low grade sources. And, in the case of waste dump leaching, there is a tremendous resource in-place that has the mining cost already off the books. This paper updates current US copper solution mining trends. Solution mining systems Schlitt (1980) summarized the characteristics of the principle leach systems in the US. He pointed out that the wide variations in copper deposits make solution mining a more site-specific activity than conventional mining and milling. Heap leaching is usually selected for moderate to high grade ores having a copper mineralization that is amenable to acid leaching (oxides, silicates and certain sulfides). Higher grade ores mined specifically for heap leaching are usually treated to optimize copper extraction, therefore, crushing and some pretreatment (acid curing) may be justified. On the other hand, dump leaching practice usually involves leaching low grade waste rock placed on large dumps as dictated by topography and haulage costs. Mine waste is therefore treated in an uncrushed run-of-mine condition. Finally, in situ leaching is appropriate for either very deep ore bodies or for recovering copper from low grade rock left behind in abandoned pit walls, stopes, and subsidence zones from earlier mining activities. True in-situ solution mining should be defined as the leaching of ore in its original geologic setting. Heap leaching Heap leaching has a long history as a hydrometallurgical process for copper recovery. The methodology of heap leaching established at Rio Tinto in Spain more than 300 years ago is basically the same as that used today. Processing concepts, such as solution management (sprinklers and leach/rest cycles) and copper

Jan 11, 1986

By A. E. Harnsberger

IT is obvious that details such as the physical and chemical properties and methods of heat-treating of the materials mentioned must be omitted in a paper on the subject of materials used in oil-refinery pumps1. Only sufficient identification is given to enable the reader to find additional information from already published data. Also, the subject covers many operating conditions, but only the most important services can be discussed here. To the oil refiner, the pumping equipment is of vital interest. Practi-cally every refinery operation, from the charging of crude oil to a dis-tillation unit to the shipping of refined products, involves some form of pumping machinery. Intermediate refining stages involve a great variety of pumping machinery to carry out successfully the aims of the refinery technologist. Temperatures at which oils are handled vary from -50° F. to 900° F. Pressure may vary from subatmospheric to 2000 lb. per, sq. inch. The selection of the proper materials involves a careful consideration of the conditions under which the particular pump must operate. The four most important considerations are temperature, pressure, corrosion, and abrasion or wear. Consideration of temperature may be divided into three parts: (1) extremely low temperatures of the order of -50° F.; (2) temperatures at atmospheric or slightly above; (3) temperatures from 200° to 900° F. Pressures fall into two groups: (1) pressures reached by ordinary trade pumps of the order of 200 lb. per sq. in., (2) extreme pressure conditions involving pressures as high as 2000 lb. Noncorrosive and corrosive oils can be treated differently. Under the latter falls corrosion in the presence of water, which will occur up to 250° F. The second type of corrosion occurs in high-temperature pump-ing equipment, with temperatures from 450° to 900° F., largely caused by sulfur compounds. There are also other corrosive conditions met with

Jan 1, 1935

By A. E. Harnsberger

IT is obvious that details such as the physical and chemical properties and methods of heat-treating of the materials mentioned must be omitted in a paper on the subject of materials used in oil-refinery pumps1. Only sufficient identification is given to enable the reader to find additional information from already published data. Also, the subject covers many operating conditions, but only the most important services can be discussed here. To the oil refiner, the pumping equipment is of vital interest. Practi-cally every refinery operation, from the charging of crude oil to a dis-tillation unit to the shipping of refined products, involves some form of pumping machinery. Intermediate refining stages involve a great variety of pumping machinery to carry out successfully the aims of the refinery technologist. Temperatures at which oils are handled vary from -50° F. to 900° F. Pressure may vary from subatmospheric to 2000 lb. per sq. inch. The selection of the proper materials involves a careful consideration of the conditions under which the particular pump must operate. The four most important considerations are temperature, pressure, corrosion, and abrasion or wear. Consideration of temperature "may be divided into three parts: (1) extremely low temperatures of the order of -50° F.; (2) temperatures at atmospheric or slightly above; (3) temperatures from 200° to 900° F. Pressures fall into two groups: (1) pressures reached by ordinary trade pumps of the order of 200 lb. per sq. in., (2) extreme pressure conditions involving pressures as high as 2000 lb. Noncorrosive and corrosive oils can be treated differently. Under the latter falls corrosion in the presence of water, which will occur up to 250° F. The second type of corrosion occurs in high-temperature pump-ing equipment, with temperatures from 450° to 900° F., largely caused by sulfur compounds. There are also other corrosive conditions met with

Jan 1, 1935

Much interesting data on cemented carbides has been published over a period of years which, when classified and pieced together, gives a clear picture of this special branch of powder metallurgy. This is an attempt to present the essential information in an ordered account.THE HARD CARBIDES-THEIR PROPERTIES AND PREPARATIONThe so-called hard or refractory carbides are the carbides of a number of metals which are grouped together in the Periodic Classification. These metals are in groups IV, V and VI. They are titanium, vanadium, chromium, zirconium, niobium (columbium), molybdenum, hafnium, tantalum and tungsten. These carbides have attracted the attention of chemists because of their remarkable properties. They possess very high melting points, and are rather difficult to prepare in the pure state. Their outstanding propertyis their extreme hardness, which they share with certain other carbides, such as those of silicon and boron. In addition, these compounds possess distinctly metallic properties, such as lustre (in fused specimens) and high thermal conductivities.(l)t They are capable of forming alloys in two ways:1. With metals, particularly those of the iron group. 2. With each other (a case of solid solubility).The constitution of these substances is not that of ordinary salts, which obey the usual valency rules, but must be likened to that of certain intermetallic compounds. Actually they are "interstitial" compounds(2), that is, they are formed from the ordinary metallic lattice by the insertion of the relatively small carbon atoms in the interstices.. The energy required to fill the lattice completely is high, and this explains the difficulty often found in obtaining the exact stoicheiometric compound. Thus the carbides can have a range of composition, and can be considered as solutions of carbon in the respective metals.Physical Properties of the CarbidesThe hardness of these compounds is so great that it is difficult to compare the individual compounds on this basis. Becker(l) gives values on Moh's scale, which are not very accurate and are of no great value. Burden(3) has reproduced a diagram by Hatfield which indicates that the cemented carbides are between 1,400 and 2,000 on the Vickers diamond scale. However, the pure carbides are harder, tungsten carbide being about 2,200. Hoyt(4) describes a method of measuring hardness applicable to powdered specimenswhereby the powder is rubbed on a standard block of cemented tungsten carbide under standard conditions, and the rate of wear is determined. In...

Jan 1, 1942

LAKE MARGARET is situate high up on the West Coast Range of Tasmania, and lies in a roughly triangular valley formed by the ridge of Mount Sedgwick on the south, the ridge formed by Mounts Geikie and Tyndal on the west, amid a ridge connecting Mounts Geikie and Sedgwick on the east. Any description of this hydroelectric installation, however brief, naturally divides itself into the following sections:1. STORAGE BASIN, &c. 2. DAM. 3. PIPE LINES. 4. POWER STATION. 5. TRANSMISSION LINES. 6. SUBSTATION 7. VARIOUS WORKS utilizing the power.The Storage Basin used is the natural lake itself, which has a maximum length of 110 chains, a maximum width of 40 chains, and a mean arelj. of 300 acres. The water-level of the lake, which has been maintained by a natural dam, is 2143 ft. above sea-level. The approximate catchment area at present appropriated is 7 sq. miles, and the rainfall, on the average, about 144 in. per annum. It is possible to increase this catchment area by suitable races, &c. Dam.-The dam constructed is of very small dimensions, and is not a storage dam in the usual sense of the term. The natural storage ot-the lake itself was used by means of a channel cut through the natural dam and thence to the mouth of the lake, the lake level being thus temporarily lowered while the outlet pipes, screens, &c., were placed in position, and the channel was then closed again with a concrete wall in which the pipes and screens are set. This channel was cut partly through rock and partly through sand and conglomerate boulders for a total...

Jan 1, 1915

By S. G. Malghan

This paper reviews uses of sodium sulfide in the flotation of oxide minerals of copper, lead, and zinc. The activation and depression effects of sodium sulfide are of particular importance because of their applications with oxidized lead and copper ores. In spite of its industrial importance, the nature of the heterogeneous reactions between sulfide ions in solution and the surface of oxidized minerals has not been fully understood. Hence, proposed mechanisms of the sulfide action in flotation, methods of measuring and monitoring sodium sulfide in flotation pulps, and variables influencing the sulfide addition are analyzed. Recent studies on sodium sulfide addition to flotation pulps, monitoring its concentration, and the optimum dosage control using platinum and/or sulfide specific ion electrodes are discussed.

Jan 1, 1987

By B Bamford

High speed diamond cutting has extensive applications in civil and mining engineering. A project involving the diamond sawing of black granite is investigating the nature of the diamond cutting process. A sawing machine was devised to adjust the cutting load and measure cutting speed. Cuttings were collected for size distribution analysis. The surface produced by interaction between diamond. grits and the rock was subjected to microscopic investigation. Increasing load prompts the proportional increase in the cutting rate. But the mean size of cuttings shows little change. The photomicrographs of the cutting tracks indicate neither patterns of crack formation nor signs of the ductile behaviour of the rock. A diamond cutting model for hard rock is formulated on these observations. Diamond cutting is a process of surface failure, which advances in four stages. The polycrystalline characteristics of a hard rock and the action of high-speed diamond grits guarantee the creation of crack nuclei which develop into cracks in various directions. This network crisscrossing cracks enable the stripping of this surface layer from the rock.

Jan 1, 1992

By Shahab Alizadeh, Ahmad Khodadadi Darban, Mehdi Mohseni, Mahmoud Abdollahy

This study probed the selective separation of lanthanum and yttrium in a nitrate medium in the presence of aluminum and calcium impurities using di-(2-ethylhexyl) phosphoric acid (D2EHPA). The factors studied in a central composite design (CCD) included extractant concentration, pH, concentration ratio of total impurities to rare earth elements, and interaction of these three factors. The extraction mechanism and types of extracted metal-containing species were delineated by the slope analysis method. The obtained thermodynamic data showed that lanthanum and yttrium extraction by the D2EHPA extractant was exothermic. The extraction of both rare earth elements was accompanied by an entropy reduction. The negative magnitude of ΔS in yttrium extraction reaction suggests stronger D2EHPA-Y(III) complexation relative to La(III). As entropy decreased and enthalpy increased, the extraction process became unspontaneous. Using the proposed flowsheet, lanthanum and yttrium products with > 90% purity were obtained.

Aug 10, 2021

By T. Bhambhani, J. Jankolovits

Sphalerite flotation using copper sulfate has been performed in the industry for decades and the mechanism of Cu activation is well established. Despite its ubiquity, many practical questions surrounding copper sulfate persist. It is not clear how iron selectivity is achieved in zinc circuits given the propensity of iron sulfides to be activated by copper. Also, the large variation in copper sulfate dosages across different plants and ore types cannot be explained. Lastly, Zn flotation with greatly reduced copper sulfate dosages attracts significant interest and has been demonstrated in certain laboratory settings, but no information is available on why those laboratory solutions have not been adopted in plant practice. Flotation studies are presented that demonstrate that Zn flotation with very low copper sulfate dosages is possible when using certain novel collectors that are not practised in the industry. However, these reagent schemes are impractical because of a heretofore unappreciated and critical role that copper sulfate plays in Fe rejection. With both very low and standard copper sulfate dosages, copper sulfate influences both Zn flotation and Fe rejection. The results highlight the multifaceted role of copper sulfate in zinc flotation and the need to holistically consider complex systems’ behaviour to understand flotation reagent mechanisms and optimise plant performance. Keywords: Sphalerite flotation, metal activation, copper sulfate, iron rejection

Jan 1, 2020

By W. R. SHAHAN, W. R. Reed, J. P. Rider

Roof bolter operators may be exposed to high respirable dust concentrations on continuous miner sections with blowing face ventilation when bolting is performed downwind of the continuous miner. One solution to reduce the high respirable dust concentrations is to use a canopy air curtain (CAC) to deliver clean air from a filtered blower fan directly to the bolter operators under the canopies. The influence of CAC installation on the airflow and dust dispersion around the location of the roof bolter operator can be evaluated by using computational fluid dynamics (CFD). 

By Somayeh Dashti, Ehsan Vahidi, Fereshteh Rashchi

"The main goals in zinc electrowinning process are decreasing of power consumption and increasing of current efficiency. In this study, the electrowinning of zinc in the presence of different additives in electrolyte were established and Arabic Gum, Gelatine, sodium lauryl sulphate and l-hexyl-3-methylimidazolium hydrogen sulfate in the five levels using Taguchi method was examined. In our previous researches, using orthogonal array, effect of zinc electrowinning parameters such as anode type, current density, sulphuric acid concentration, temperature and zinc ion concentration was studied and the optimized conditions for zinc electrowinning was obtained. Anode composition: Pb-Ag 0.5%-Sn2%-Sb1%, current density (A/m2):500, acid concentration (g/1):165, temperature: 60°C, zinc ion concentration (g/1):70. The main goals in zinc electrowinning process are decreasing of power consumption and increasing of current efficiency. ln this research, the effect of four additives: Gum Arabic, Gelatine, sodium lauryl sulphate and an organic material in the four levels with Taguchi method was examined. ln fact the effect of electrolyte environment and determining the best electrolyte under the optimized conditions is the main aim of this study.IntroductionDue to its low cost and abundance, zinc is widely used in the production of brass, galvanized steel, sacrificed anodes and primary and secondary batteries [I]. Some 80% of world primary zinc production is derived via roast-leach-electrowinning processes [2-4]. In the electrowinning process to both improve final product quality and current efficiency the leachate should be purified [5].To produce zinc a current method is to extractit from acidic zinc sulphate solutions by electrolysis with aluminum cathodes and insoluble lead-based anodes [6]. Though the electrolytic processing of zinc has been performed for many years, there are still current efficiency problems in the cathodic process. These low efficiencies (88- 93%) have a serious impact on the costs associated with the energy consumption. On the other hand, these low efficiencies increase energy consumption and decrease the quality of the surface morphology [7- 8]."

Jan 1, 2012

The structure of the Bulli coal seam at Appin Colliery was detailed by the seismic reflection method. This unusual application of the seismic method was possible because there is a reflector near the seam as was revealed during exploration for petroleum in an area north-west of Appin. The reflector, which was at a depth of 1,500 ft, was shallow by normal reflection survey standards. Measurement of the seismic velocity at two ventilation shafts showed that the reflector was probably the Bulli coal seam. Accurate depth control was established from previous drilling results.INTRODUCTIONAppin Colliery, situated on the Southern Coalfield of N.S.W. (Fig. 1), is being developed to supply coking coal to the Port Kembla steelworks of Australian Iron and Steel Pty. Ltd. The colliery is mechanized and a detailed knowledge of structure, particularly faulting, is important in planning the workings.The Bulli seam, which is approximately 9 ft thick, and between 1,500 ft and 1,800 ft below the surface, is worked in the colliery. It is the uppermost member of the Permian Coal Measures and is overlain by Triassic rocks, which consist of thick sandstone beds containing beds of coloured shales, and which are subdivided into the Narrabeen Group, the Hawkesbury Sandstone, and the Wianamatta Group.In the early stages of development of the colliery, surface geological mapping and diamond drilling provided information on structure. Generalized results of the mapping are shown on Fig. 2. Drilling indicated that the physical and chemical properties of the Bulli seam are relatively constant, and that the seam is nearly horizontal, the average dipbeing about 1 in 25 to the west.

Jan 1, 1965

By V. Vogt

During the phosphating of car bodies containing aluminium, the employed phosphating chemicals zinc, manganese and nickel are, for thermodynamic reasons, only used to a limited extent for the desired surface coating. The major proportion of these metals is discharged together with the incidental cryolite-containing phosphating sludges and the rinse water. Commissioned by the German Federal Ministry of Education and Research (BMBF), the Institute of Mineral and Waste Processing, Waste Disposal and Geomechanics at the Clausthal University of Technology has developed a two-stage process for the production-integrated recovery of the dragged out chemicals and for closing the rinse water cycle for Audi AG. During the first stage, the phosphating chemicals are recovered by means of leaching. In the second stage, the rinse water is treated by means of electroflotation followed by an ion exchanger.

Jan 1, 2014

By W. W. Heywood

"IntroductionCIRCULAR structures on the Arctic islands were first noticed early after World War II. During the indexing of the 1950 Royal Canadian Air Force photographs their occurrence was brought to the attention of the Geological Survey of Canada by Mr. W. B. Waugh, Surveyor General. As a result, I. C. Brown ( 195l) of the Geological Survey of Canada studied the air photographs of these structures and discussed theories that might explain their origin. The author, as a member of the Geological Survey of Canada, spent several months in 1952 and 1953 in reconnaissance study of the geology of Ellef Ringnes island, using the Isachsen meteorological station as a base. Twelve days in the summer of 1953 were spent mapping the Isachsen dome and adjacent areas. The Isachsen dome, one of several similar structures occurring on Ellef Ringnes island, is situated 35 miles southeast of the meteorological station.PhysiographyEllef Ringnes island is a mature, stream dissected plain having an average elevation of about 400 feet. The surface of the plain is undulating with a relief of about 150 feet; only a few of the numerous streams that form a dendritic drainage pattern have eroded valleys this deep. Long, low, cuesta escarpments cross' the plain, which is underlain by sedimentary rocks of Lower Cretaceous and possibly younger age. The sedimentary strata have a low regional dip to the southeast; exceptions are found in the vicinity of the domes, where the strata are up-turned, and in the plateau region, northeast of Deer bay, where they are flat lying. The plateau, which is underlain in large part by basalt, is deeply dissected and has an average elevation of 1,000 feet."

Jan 1, 1955

By R. W. Smith, A. Raichur, M. Misra, I. A. H. Schneider

The concept of microorganisms as chemical reagents (flocculants, flotation modifiers and flotation collectors) is quite new. Potential uses for microorganisms include their use in place of certain conventional flotation reagents and as flocculating agents in minerals engineering processes. In addition, in some studies micro-organisms have been used to modify mineral surfaces and, thus, the flotation or flocculation of the minerals.

Jan 1, 1995

By A. H. Lee

Discussion of the paper of H. P. HOWLAND, printed in Bulletin No. 111, March, 1916, pp. 627 to 650. A. H. LEE, Buffalo, N. Y. (communication to the Secretary*). The statements and results recorded in Mr. Howland's paper can be accounted for by the use of coke with a low sulphur content (0.60 and under). This allows the furnaces to be run on a small volume of acid slag, which it is presumed was done in Mr. Howland's practice. H. A. Brassert has admitted that this was the largest factor in low fuel consumption in his practice. Where the coke contains from 1.00 to 1.25 per cent. of sulphur the situation is quite different and I doubt whether the results mentioned by Mr. Howland could be obtained under such circumstances. ` N. M. LANGDON, Mancelona, Mich. (communication to the Secretary + ).-Gruner's ideal working (which is but a statement of the law first enunciated by Bell) as given in Gordon's Translation of Studies of Blast Furnace Phenomena, "supposes that the reduction of the oxide of iron is effected by the CO only, without intervention of solid carbon." This ideal, if reached, would mean theoretically perfect or 100 per cent. efficiency of reduction. The workings of the large number of furnaces as given in Bell's and Gruner's great works do not show that this standard of perfection ever was reached. This problem has been worked out by the writer for a number of furnaces, and his results, as well as those given by others, all show a failure to reach perfection. Some furnaces, however, approach nearer to perfection than others. The "ideal" as given by Gruner was not stated as a solved problem in blast-furnace practice, but as an ideal to the attainment of which furnace managers should strive. A study of the factors involved from every angle is interesting and instructive and the paper on this subject contributed by H. P. Howland is no exception to the rule. This article is fairly open to criticism, not because of the unique method of presenting the subject, but for the reason that, as the writer conceives, erroneous assumptions are taken which lead naturally to incorrect conclusions.

Jan 7, 1916

By Z. H. Zhou

It is difficult to remove cadmium from raw indium using only electrolytic refining because their standard potentials are similar. In this paper, physical and chemical methods were used to remove Cd from raw indium. Indium metal is vacuum refined for two hours at 400°C with a vacuum pressure of 20 Pa. In this process, 99.70% of the Cd can be removed. The removal rate of Cd reaches 90% to 95% when indium is further smelted for 10 minutes in a 20% glycerin solution of KI and I2 at 180°C. When pre-indium is electrolytic refined in an In2(SO4)3-H2SO4 system, in which the indium content is 80 to 100 g/L, the pH is 2.0-3.0 and the current density is 80 to 100 A/m2, the contents of the impurities decrease and the purity of the indium product reaches 99.99%.

Jan 1, 2007