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By Allen D. Look, Norman King

For many years, much thought and effort have been devoted to the achievement of safety in the use of explosives by those interested in the preservation of human life and the protection of property. As a result, we now have adequate rules pertaining to the safe use of explosives , which, if observed, would prevent many, perhaps ail , of the explosives accidents that yet occur . Although the rules respecting the use of explosives are believed to be well - known, many accidents occur because they are disregarded . The mental awareness aroused by a tragic accident usually will cause safety precautions to be taken for a while ; however , this awareness gradually disappears unless a sincere effort is made permanently to prevent similar accidents . Frequently, because safe methods are more irksome than unsafe methods , the lessons taught by accident experience are forgotten in a short time , vigilance is relaxed , and there is a gradual return to unsafe , easy methods of performing work. If the preservation of human life is important , the unfortunate experiences of others and the lessons taught by them should be applied to reduce unnecessary loss of life . The value of a life lost as the resuit of accident should be calculated not only from the monetary and humanitarian standpoint but also according to what the accident could contribute in the way of saving other lives and suffering . This saving of other lives can and will , if the lessons from unfortunate accidents are applied , convert a loss to a gain a gain of such magnitude that the accident victim could be considered

May 1, 1944

By Harry M. Mikami

Chromite is the only ore mineral of metallic chromium and chromium compounds and chemicals. Because of this fact, chromite and chrome ore are used synonymously in trade literature. In commercial market quotations, chrome ore is the term commonly used. Chromite per se, because of properties imparted by its chromium content, is used in refractories and in special purpose moulding sands for metal casting. There are many other minerals containing some, generally minor, amounts of chromium, but none are commercial sources of the element (Thayer, 1956, p. 15). Chromium and chromite have many diverse uses that, directly and indirectly, critically affect vast segments of our modern industrial system. Most important are probably the metallurgical applications wherein chromium is a component of heat, abrasion, corrosion, and oxidation-resistant, and high strength alloys of many types. Stainless steels are the largest volume category of chrome-bearing alloys. Chromium chemicals are used in leather tanning, in pigments, dyes and mordants, printing, :hemica1 process industries, photography, pharmaceuticals, metal plating, pure chromium metal production, and for many other purposes. Chromite is a necessary constituent in basic refractories indispensable for the production of steel, copper, cement, and glass. Under present economic-political conditions, he U.S. and for that matter, North America, has virtually insignificant ore reserves of chromite. There are chromite deposits, as will be described, but they would only be used under highly abnormal conditions if all outside sources were cut off. All chromite used in the U.S. is imported from the eastern hemisphere in which are contained the principal world reserves. As the main suppliers in 1971-72 were the USSR, Turkey, Republic of South Africa, Philippines, and Rhodesia, the strategic nature of chromite is obvious.

Jan 1, 1975

By S Hall

Mining schools around the world, many unfortunately now closed, were often established to teach the techniques of narrow vein mining and associated processing to students studying part-time while working in the industry. This arrangement ensured graduates (or æassociatesÆ) had a mix of skills and knowledge invaluable to the industry.It is argued that there is still a need to educate students in these narrow vein techniques and that there will be a growing demand for such graduates with a high level appreciation of this type of mining. There is also a need for innovation in narrow vein mining and processing to develop specific technologies and allow the use of techniques applied in æbulk miningÆ to achieve improvements in productivity, safety and economic performance.This paper aims to review the situation with regard to education and innovation in narrow vein mining.CITATION:Hall, S, 2012. Narrow vein education - back to the future?, in Proceedings Narrow Vein Mining 2012 , pp 23-26 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 26, 2012

By J. D. Lubahn

The influence of precipitation from solid solution on the subsequent deformation resistance of alloys is well known. However, the influence of precipitation or aging that occurs simultaneously with deformation may be entirely different and of considerable importance. It is thought1 that the presence or absence of a yield point jog in impure iron at room temperature and the presence or absence of discontinuous flow at higher temperatures may be directly related to aging phenomena, particularly since the yield point jog is absent when the carbon and nitrogen are sufficiently removed.2 As a preliminary attack on the problem of simultaneous aging and deformation, three kinds of tests—constant strain rate tensile tests, constant load creep tests, and variable strain rate tensile tests—were carried out on an age hardenahle aluminum alloy. Constant Strain Rate Tensile Tests Stress-strain curves at a strain rale of about 0.001 min-1 were obtained for specimens of 61S that had been quenched into liquid nitrogen after a one-hour solution treatment at 521°C, then aged at room temperature 10 min., 20 min., 4 hr, and 26.5 hr before testing. Strain-time curves were obtained on the same chart with the stress-strain curve by means of an auxiliary pen, driven parallel to the axis of the chart drum at constant speed by a synchronous motor and gear chain. The angle of rotation of the chart drum was proportional to strain. The strain rates reported are the measured slopes of the strain time curves. Constant strain rate was approximated (within a factor of 2) by manual adjustment of the oil inlet valve of the hydraulic testing machine in such a way that the course of the recorder pen was parallel to pre-drawn strain-time lines of the desired slope. The specimens were machined from 9/16 in. rod. The cylindrical portion was 0.357 in. in diam by 13/4 in. long and

Jan 1, 1950

By K. P. Stricker, H. Keddeinis, K. Grebe

Recent investigations by Mannesmann Research have shown that disintegration of sinter with widely varying quality levels is subject to a much more complex set of influences than was previously assumed. It was confirmed that disintegration at temperatures between 300° and 600°C (570° and 1,110°F) is triggered by the degradation of hematite. The specific tendency of hematite to disintegrate is, however, not constant: sinters containing the same amount of hematite can show widely differing disintegration tendencies, depending on structural homogeneity, porosity, and gangue quantity. Sinters with heterogeneous structures transmit stress to the hematite phase and this favors disintegration. Another factor is the brittleness of the glassy silicate phase, which can be influenced even by small modifications of minor gangue constituents.

Jan 2, 1984

By M. C. Fuerstenau

A number of interesting and. important phenomena were revealed during a study of the response of beryl to sulfonate flotation (1). Perhaps the most important observation is the effect of various cations on flotation response. Experiments showed that in the vicinity of pH = 3. 0, about three ppm Fe.+++ increased recovery of leached beryl from about 60 to 100 per cent, whereas about four ppm Ca++ reduced the recovery from 60 to 2 per cent. With the exception of ferric iron, all of the other cations investigated reduced flotation recoveries drastically at this pH. As postulated in the paper "Sulfonate Flotation of Beryl", (1) even with low concentrations of polyvalent cations and sulfonate (on the order of one ppm), cation¬ sulfonates are precipitated immediately in solution. That is, blueish-white clouds .were noted to form after given additions of salts to. known solutions of sulfonate. Furthermore, it was also shown that one-hundred-fold more ferric iron than necessary to form the precipitated cloud had to be added to effect complete flotation. In other words, some form of solid ferric sulfonate was found to function as the collector in these systems. The form of the compound was suggested to be Fe (RSC3)2OH and that bonding to the surface occurs through the hydrogen of the hydroxyl. As the form of this compound was shown to be dependent on the extent of hydrolysis of ferric iron, it is to be expected that ferric iron will be unique in some pH region. Further, if the presence of hydroxyl in the neutral precipitated compound is of primary importance, then other cations should function similarly but at different values of pH, since they will hydrolyze at different concentrations of hydroxyl ion. To determine whether the premise of hydrolysis is correct, the study was extended to quartz systems lit the presence of various cations at various values of pH.

Jan 1, 1964

By R. Wirth, B. Orberger, C. Wagner, A. Tudryn, B. Baptiste, S. Miska, Université Paris-Sud

Banded iron formations (BIFs) comprise complex textures and mineralogy, which result from fluid-rock interactions related to high and low temperature alteration. The initial iron oxy hydroxide mineralogy and associated phases such as carbonates, quartz, apatite and phyllosilicates were transformed leading to an upgrading of these BIFs into the world’s largest source of iron ore. In low-grade BIFs, a large part of the iron is related to micro- and nano- metric iron-bearing inclusions within micrometric quartz and/or carbonates (mainly dolomite). We studied laminated jaspilitic BIF samples from a drill core containing 26.71 wt.% total iron, 0.2 wt.% SiO2, 0.32 wt.% MnO, 15.46 wt.% MgO, 22.32 wt.% CaO, 0.09 wt.% P2O5, < 0.05 wt.% Al2O3, 0.15 wt.% H2O and 34.08 wt.% CO2 (Aguas Claras Mine, Quadrilatero Ferrifero, Brazil). Bright rose coloured dolomite and quartz bands alternate with massive specular hematite bands. Raman spectroscopy, X-ray diffraction and FIB-TEM analyses reveal that the micro- and nanometric inclusions in dolomite are mainly hematite and minor goethite, partly occurring as clusters in voids. Curie Balance analyses were carried out at different heating steps and temperatures on whole rock samples and a synthetic mix of decarbonated sample and pure dolomite. X-ray diffraction on the products of the heating experiments shows that that hematite is stable and new phases: magnesioferrite (MgFe2O4), lime (CaO), periclase (MgO), portlandite (Ca(OH)2) and srebrodoskite (Ca2Fe2O5) were formed between 680°C and 920°C. These finding gives hints to optimizing the beneficiation process, as the presence of hydroxyl ions bearing goethite micro- and nanoinclusions lowers the sintering temperature. Prior separation of coarse hematite and barren dolomite and quartz, followed by lower temperature sintering of the inclusionbearing dolomite/quartz leads to transformations into phases with higher magnetic susceptibilities (such as hematite and magnesioferrite). The entire Fe and Fe/Mg oxide feed (the priorly separated fraction added to the sintered fraction) can then pass through wet-high intensity magnetic separation after crushing.

Jan 1, 2016

By G Brudek, P Elestedt

Schalker Eisenh&#252;tte und Maschinenfabrik GmbH, Nordic Minesteel Technologies and Bombardier Transportation have developed an evaluation tool that considers the main cost drivers of the rail, truck and conveyor haulage systems on the market today. In almost every circumstance, the advantages of a haulage solution are clear. A haulage system is outlined that is fully automated, including driverless operation, and that provides increased tonnage, safety and equipment life and reduced maintenance downtime. The haulage system has been implemented by a number of companies, including Codelco, LKAB and Freeport’s Grasberg mine. CITATION:Brudek, G, Elliott, R P and Elestedt, P, 2016. Moving mORE for less, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 535–542 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By Ralph C. Flow

In Cleveland County, North Carolina, 1 ½ miles south of Kings Mountain, Foote Mineral Co. operates an open pit for the production of spodumene, feldspar, mica and commercial stone. Spodumene concentrate is sent to Foote Mineral&apos;s Sunbright, Va., plant and to other customers. Exton, Pa. and New Johnsonville, Tenn., plants produce lithium com- pounds sold to the oil industry for multipurpose lithium-base greases, to the metal industry as welding flux, to the air conditioning market and to the glass industry. Ceramic-grade spodumene, feldspar, and mica concentrates go to other processing companies from the Kings Mountain plant. Waste amphibolite is delivered to a neighboring quarry operation. Geology and exploration of the deposit have been described by T. L. Kesler, Chief Geologist of Foote Mineral Co., in the September 1961 MINING ENGINEERING. Measured ore reserves as published at that time were 20.7 million tons. The ore deposit consists of a series of lithium-bearing pegmatites enclosed in amphibolite and mica schist wall rocks. The general strike of the pegmatites is northerly, and in the southern part of the pit, they dip slightly towards the west. The largest body being mined has a fairly uniform thickness of about 200 ft. Other pegmatites in the pit area range from 20 to 100 ft in thickness. Minerals in the pegmatites are 20% spodumene, 32% quartz, 6% muscovite, 41 % feldspar and 1 % trace minerals.

Jan 10, 1962

By J. F. Hutwelker

A pilot plant was constructed and operated to investigate the column flotation of 20 x 200 mesh North Carolina phosphate ore, using high throughput, high solids operating conditions developed at the NCSU Minerals Research Laboratory. Flotation was performed at 45% solids in a 9.5 cm (3.75 in.) diameter by 2.26 m (7.4 ft.) tall column at throughputs of 19.1 t/hr/m2 (2.0 stph/ft2) and 31.7 t/hr/m2 (3.3 stph/ft2). Recoveries in excess of 98% of the phosphate value were obtained at the lower throughput -- while obtaining concentrate grades containing over 28% P205 (61.2% BPL) at that recovery. Recoveries of about 95% of the phosphate value were obtained at the higher throughput, while making a concentrate averaging 27.6% P209 (60.3% BPL). In addition, a better understanding of the variables governing the column flotation of coarse nonmetallic minerals was gained. Low air flow rates adversely affected concentrate grade at the lower throughput. At the higher throughput, phosphate recovery decreased at an elevated air flow rate. An unexpected result of the study was the effect that frother type had upon phosphate metallurgy. Use of Nottingham Econofroth 925 provided better flotation selectivity than American Cyanamid F-65 at the low throughput. This is significant since the high&apos; throughput tests were conducted with F-65 exclusively. It is reasonable to expect further improvement in high throughput performance when the optimal frother type and dosage are determined.

Jan 1, 1993

By Maurice Ewing, J. A. Peoples, J. W. Peoples, A. P. Craby

The purpose of this paper is to present the results of the application of the earth-resistivity method of subsurface investigation to the problem of locating seams of anthracite coal beneath a mantle of soil and subsoil. Details are given of the successful use of this method in locating the outcrops of anthracite seams in actual prospecting. The presence of the outcrop of an anthracite seam is indicated at points where electrical resistivity tests showed relatively low readings. The reason for this is that in some localities the resistivity of anthracite was found to be about 0.0001 megohm-cm. compared to 1 to 200 megohm-cm. for shales and sandstones. For two reasons it is believed that the data summarized in this paper should be of particular interest. In the first place, most of the interpretations of the resistivity survey have been checked by subsequent drilling and some by the removal of the overburden and the exposing of the anthracite seams. It is infrequent that the opportunity for checking results so thoroughly is given. In the second place, the fact that recent commentatorsl,2,3 on the application of geophysical methods to mining have concluded that direct prospecting for anthracite and other types of coal is not promising makes the good results obtained more significant. So far as the authors can learn, the only previous experiment with electrical methods in the Pennsylvania anthracite field was one made by Sherwin F. Kelly in 1921, when he used the self-potential method at Wilkes-Barre4. The profile he made does not show a very marked correlation with the geologic cross section. Kelly points out that stray currents from electric motors in the mines undoubtedly affected &apos;his results, but the experience of the present authors with stray currents from mining machinery suggests the possibility that the potentials measured by Kelly were due almost entirely to this effect.

Jan 1, 1936

By Maurice Ewing, A. P. Craby, J. W. Peoples, J. A. Peoples

The purpose of this paper is to present the results of the application of the earth-resistivity method of subsurface investigation to the problem of locating seams of anthracite coal beneath a mantle of soil and subsoil. Details are given of the successful use of this method in locating the outcrops of anthracite seams in actual prospecting. The presence of the outcrop of an anthracite seam is indicated at points where electrical resistivity tests showed relatively low readings. The reason for this is that in some localities the resistivity of anthracite was found to be about 0.0001 megohm-cm. compared to 1 to 200 megohm-cm. for shales and sandstones. For two reasons it is believed that the data summarized in this paper should be of particular interest. In the first place, most of the interpretations of the resistivity survey have been checked by subsequent drilling and some by the removal of the overburden and the exposing of the anthracite seams. It is infrequent that the opportunity for checking results so thoroughly is given. In the second place, the fact that recent commentatorsl,2,3 on the application of geophysical methods to mining have concluded that direct prospecting for anthracite and other types of coal is not promising makes the good results obtained more significant. So far as the authors can learn, the only previous experiment with electrical methods in the Pennsylvania anthracite field was one made by Sherwin F. Kelly in 1921, when he used the self-potential method at Wilkes-Barre4. The profile he made does not show a very marked correlation with the geologic cross section. Kelly points out that stray currents from electric motors in the mines undoubtedly affected &apos;his results, but the experience of the present authors with stray currents from mining machinery suggests the possibility that the potentials measured by Kelly were due almost entirely to this effect.

Jan 1, 1936

By R Hartner

Digital optical microscopy (DOM) and automated SEM-based (ASEM) mineralogy systems (MLA, QEMSCAN) have experienced significant developments within the last decade. However these developments have been independent from each other and the two mineralogical techniques have so far not yet been integrated to combine the strengths and technical benefits of both analytical platforms. This detailed comprehensive mineralogical information is critical support for geometallurgy.Major hardware and software advances in DOM in the last few years have provided important new capabilities with potential applications to automated mineralogy. These technological advances have been largely driven by sectors outside mining (eg medical pathology) and have not yet been widely adopted within the minerals industry. The advent of DOM offers significantly more automated mineralogy capabilities than traditional expert-mineralogist driven optical microscopy. This is based on advances in automated image acquisition, high resolution cameras for digital imaging, imaging of large areas through mosaic options, integration of multiple layers and application of advanced image analysis techniques.Ongoing research involves combining the outputs of DOM and ASEM-based microscopy to create new capabilities for integrated microscopy based on development of advanced cross-platform image fusion and data integration between DOM and ASEM (exploiting the benefits of both analytical platforms). This requires non-linear image registration and transfer of mineralogical identification from ASEM to DOM systems using sophisticated image manipulation and data analysis software.Examples will be given of image fusion and data registration for a range of different ore types. Image fusion techniques are demonstrated using a porphyry copper deposit sample where sulfides and precious metals are classified using the MLA and gangue mineralogy obtained from DOM images. Data integration enables creation of a library containing optical property variability information for minerals identified by the MLA; thus reducing the reliance on skilled mineral identification by supplementing human interpretation

Sep 5, 2011

By F. S. White, E. L. Kinsella

THE solids fluidization process brought out by the Standard Oil Development Co. in the early forties for catalytic cracking of petroleum enabled rapid transfer of large quantities of heat from gases to solids under closely controlled temperature conditions. As the technique developed, it was natural that applications for the process outside the petroleum industry would be sought. The calcination of limestone to &apos; quicklime requires the transfer of a large quantity of heat at high and closely controlled temperatures. For these reasons, this possible application was one of the first to be investigated. Laboratory work conducted by the Dorr Co. indicated that lime produced by solids fluidization would be of exceptional quality. Calculation of theoretical heat balances showed that savings in fuel could be expected. Accordingly, a pilot plant of 10 tons per day capacity was erected by the New England Lime Co. at Adams, Mass., to substantiate the process. Operation of the pilot plant, previously described,1 showed that excellent lime could be produced with a saving in fuel. The work also indicated the necessity of preparing feed to remove the finer fractions if dust losses were to be held to a tolerable level. A single-stage fluidized solids drier-stripper was developed to accomplish this sizing.2 Subsequently a commercial lime reactor was erected at Adams, beginning operation in June 1949, followed by air sizer facilities completed in November 1951. This paper will describe these two applications of solids fluidization. The raw material for preparation of lime by the fluidizing process is a high calcium crystalline lime stone having the approximate chemical composition shown in Table I. The stone is first prepared by crushing and grinding in conventional equipment to pass a 6-mesh sieve. After crushing, the material is sent to the FluoDry unit for drying and dedusting. Fluidized Drying and Sizing As shown in Fig. 1, the FluoDry unit consists of a 1/4-in. cylindrical steel shell, 9-ft ID by 22-ft 6-in. overall height. Attached horizontally at the bottom is a 6-ft diam combustion chamber, approximately 7 ft 6 in. long. A refractory constriction dome, consisting of first-quality fire brick shapes, partitions the inside into two sections. The lower section is called the windbox and the upper the bed compartment. The vertical wall of the shell is lined with 6-in. first-quality rotary kiln blocks. In the bottom of the windbox a hoppered section is formed with castable refractory to permit the windbox to be readily cleaned via a 6-in. screw conveyor. The combustion chamber is similarly lined with refractory shapes. On the 6-in. diam section, 4 1/2 in. of insulating brick, HW-26, are used. The inner combustion chamber is lined with 4 1/2-in. Korundal brick to withstand the high flame temperatures encountered. An 8-in. steel feed pipe, entering vertically through the top and fitted with an air-operated cone valve,

Jan 1, 1952

By L. H. Van Loon, E. G. Crayston, A. F. Heather

"IntroductionTHE PROPERTY of Madsen Red Lake Gold Mines. Limited. comprises fifty-eight claims located between Russet and Faulkenham lakes in Baird and Heyson townships of the Patricia portion of the District of Kenora. The mine is seven miles •by road from the hamlet of Red Lake. This latter centre is .connected to the Trans-Canada Highway at Vermillion Bay, Ontario, by provincial highway No. 105 which has a total length of one hundred and thirteen miles.The Madsen property went into production on August 11th, 1938, with a milling plant rated at 300 tons per twenty-four hours. Changes made in the crushing plant during October, 1938, allowed a •finer feed to be delivered to the mill and increased the milling •capacity to 400 tons per twenty-four hours. During 1948, steps were taken to add an additional 400-ton capacity unit to the milling plant. This latter work was completed by May, 1949, giving the present total milling .capacity of 800 tons per twenty-four hours.It was realized in the early 1940's that, eventually, considerable material suitable for backfilling in the mine would be required. As there were no large deposits of gravel or sand anywhere near the mine, officials of the Company considered it advisable to investigate the feasibility of using mill tailings for mine •backfill. Since Madsen mill tailings contain approximately 80 per •cent of minus-200-mesh material, it was not considered practical to use them for underground backfill without first removing the finer material. as the slimes present in a product of this fineness would without doubt preclude any drainage whatsoever. Table I gives a sizing analysis of Madsen mill tailings and Table II a quantitative chemical analysis of the ore."

Jan 1, 1954

By A Whaanga

The use of photogrammetry has greatly increased the accuracy of 3D mapping underground. However, this has not reduced the need or desire for geologists to produce plans and sections showing an interpretation of the mapped geology. At the Waihi Underground Gold Mine, a hybrid solution has been developed that utilises the accuracy of photogrammetry and mapping onto face photos with the CAD-based Deswik.MappingTM functions to create plan and section maps. These have the benefit of looking like traditional paper maps but are more spatially accurate and richly attributed with metadata that can be filtered and exported to downstream processes. Deswik.MappingTM is a tablet-based solution that allows the geologist to map digitally with a stylus. Automation is utilised for the updating of survey as-builts, approved designs, drill holes, geological mapping, vein interpretations and mine work areas, reducing the requirement to print out maps at various locations and scales. Having 3D mine software on a tablet device provides a wealth of features not available when using paper: scaling is a problem of the past; information can be turned on and off; features can be viewed in 3D; and measurements between points of interest can be calculated in 3D space, for example, between vein wireframes and drill hole sample information. A suite of custom scripts has been developed that take the spatially accurate, registered and attributed polyline data from photogrammetry scans and converts them to a geological mapping legend with vein textures, structural information, and lithological boundaries. These 3D maps can be plotted in plan or section view and satisfy the requirements of the most ardent paper map supporter.

Mar 22, 2022

By Michael M. Hamilton

In 1985, at the request of the U.S. Bureau of Land Management, the U.S. Bureau of Mines studied a 37,542-acre portion of the 57,002-acre Riordan?s Well Wilderness Study Area (NV-040-166) in order to evaluate its mineral resources. The area studied is located in Nye County, NV, about 60 miles southwest of Ely, NV. Subeconomic mineral resources of limestone and sand and gravel were identified in the study area. The Troy and Irwin mining districts, 4 miles to the west, were active between 1868 and 1963, producing small amounts of gold, silver, lead, and tungsten from mines well outside the study area. Except for minor prospecting activity, most mining activity in the study area has been since 1980, consisting of claim locations and geochemical surveys.

Jan 1, 1987

By W. Mostowitsch

Lead sulphate occurs as anglesite, and is formed in every roasting of lead sulphides or sulpho-salts containing lead. In smelting in the blast furnace an ore containing natural or artificial lead sulphate, a large part of the sulphur present goes to the formation of the intermediary product matte which requires further treatment for the recovery of the values it contains. It is therefore of importance to study the behavior of lead sulphate at elevated temperatures, both without and with reducing agents, especially as the information available gives data which are more or less conflicting. 11. Decomposition of PbS04 by Heat The dissociation of PbSO4 into PbO and SO3 or SO2 and 0 has been discussed by many metallurgists. The following data are considered to be representative. Doeltz and Graumannl found that PbS04 was not affected-by heat at 800" C.; that dissociation began at 900" C., and was rapid at 1,000° when the salt lost in 1 1/2 hr. 14.3 per cent. of its weight, the dry salt containing 26.43 per cent. SO3. Hofman and Wanjukow2 summarize their work upon the dissociation of metallic sulphates with the statement that the decomposition of PbS04 begins at 195&apos; C., but progresses very slowly, with the formation of the basic salt 6PbO.5SO3 at 705"; that this salt undergoes a transformation at 847") begins to be decomposed at 888") to sinter at 896", and to fuse at 910"; rapid dissociation begins at 952") and is accompanied by volatilization of PbO; retardations at 958" and 962" indicate an acceleration of decomposition which, however, is not complete. Proske3 found that PbSO4 gave off at 900" C. in 30 min. only 0.63 per cent. of its 803, and that the loss increased with

Jan 1, 1917

By K. S. Fraser, R. Frischmuth

High temperature pressure oxidation (>190°C) is a wellrecognized and versatile metallurgical oxidative pre-treatment process commonly used to liberate gold from refractory sulfide ores and concentrates. The pressure oxidation of refractory gold ores was first commercially applied in 1985, at Homestake Mining Company’s McLaughlin mine in the United States. Since that time numerous refractory gold and other high temperature pressure oxidation facilities have been built throughout the world. The design of each facility was met with unique challenges and opportunities which have led to an array of plant configurations, pressure oxidation autoclave sizes, and sulfide oxidation capacities. This paper presents a historical review of high temperature pressure oxidation operations and current projects in execution with a focus on the autoclave vessel design, circuit configuration, and unit sulfide oxidation capacity as a basis for characterization and comparison.

Mar 2, 2022

By Victor De Ysassi

THE iron mines of Spain are located on the mountain ridge forming the boundary between the, Teruel and Guadalajara provinces, called Sierra Menera. They form a property of 25 mines extending over an area of 1,677 hectares (4,140 acres) situated at a height varying from 1,200 m. (3,940 ft.) to 1,500 m. (4,920 ft.) above sea level. The deposit follows the direction north to south; huge masses of ore are being found both on the slopes and at the summit of the Sierra. The ore occurs among quartzites and magnesite limestone, in some places overlaid by quartzite 15 in. (50 ft.) thick; in some others (and this is more general) the ore is overlaid by earth and boulders of quartzite origin,; this layer is about 8 m. (26 ft.) thick. The ore beds occupy the geological horizon of the Superior Trias or Muschelkask, which are here in direct contact with the Silurian quartzites. The lime-stones have been more or less transformed. There is ample evidence to show that these mines were worked in very ancient times-objects and tools employed in mining by the ancient Romans and Arabs are to be found plentifully in old workings which extend down into the deposits. It has been estimated that more than 10,000,000 tons of ore were mined in the old days in this district and carried to the primitive forges in the vicinity where iron of much renown in Spain was extracted. Remains of more than 20 of these forges are found in the neighborhood of Sierra Menera and are usually situated near waterfalls and forests. Much investigation has been carried on for the purpose of determining the quantity of ore to be found in these mines, but no exact calculations can be made at present. When the investigation is completed it will surely be found that the deposit contains a much larger quantity than the 100,000,000 tons indicated by the present workings.

Jan 2, 1916