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By S. Moodley

In the chloride process for Ti02 pigment production, various titania feedstocks (i.e. rutile, synthetic rutile, slag, and upgraded titania slag (UGS)) are chlorinated in a fluidized bed reactor with petroleum coke at temperatures between 1000°C and 1100°C to yield gaseous metal chlorides. Although feedstock preference is largely based on Ti02 content, feedstock physical properties (i.e. density, sphericity, size distribution, and porosity) differ; these differences will affect fluidization behaviour and can inadvertently affect conversion efficiency. For example, a high carryover from the reactor reduces particle residence time and decreases conversion rates. Owing to dwindling rutile reserves in the world, most chloride producers are forced to feed blends of feedstocks to their chlori¬nators; and so it becomes important to understand whether blends have an effect on the hydrodynamic properties of the bed. This paper describes the physical characterization of different feeds and the determination of the elutriation constants for slag, rutile, synthetic rutile, and a blend (i.e. 50 wt% rutile, 50 wt% slag). A common feature of the tests was that particles finer than 75 Km tended more than any other size to be elutriated. The tested rutile, classified as a Geldart Group B material, had the lowest carryover, whereas the slags had the highest. Interestingly, the elutriation constant (ki) of the blend is lower than those of either of its individual components.

Jan 1, 2012

By S. F. Radtke, J. A. Snyder, R. M. Scriver

DISCUSSION, J. R. Long presiding R. I. Jaffee (Battelle Memorial Institute, Columbus, Ohio)—The authors have written a fine and important paper, and are to be congratulated. I do not entirely follow their discussion of the relationship between the ductility of titanium and its crystal structure. Since high purity titanium is extremely ductile, being capable of cold reductions of ovei- 99 pct, its ductility cannot be unduly restricted by its hexagonal crystal structure. It is true that interstitial solid solutions of nitrogen and oxygen do have a restricting effect on ductility, but this would appear to be an alloying effect rather than a crystal structure effect. The point made by the authors concerning the relative ductility between forged and rolled titanium does not appear to be conclusive, either. It would appear that in the same condition forged material would have equivalent or better ductility than sheet material. The difference between the ductility reported for forged bar and annealed sheet in Table I may be the result of a greater degree of cold work in the as-forged condition. S. F. Radtke, R. M. Scriver, and J. A. Snyder (authors' reply)—We appreciate the discussion by Dr. Jaffee. His point is well taken that the hexagonal structure of titanium does not, in itself, restrict the ductility of iodide material and, therefore, should not be limiting in this case. It is true, however, that the ductility of different grades of titanium is not necessarily related to their hexagonal structure but more likely to their orientation and composition. It is also true that the presence of small amounts of foreign elements in hexagonal metals may have more pronounced influence on ductility than a corresponding quantity in cubic metals. Average values from a large number of tests might show relatively better ductility for forged titanium than is recorded in Table I. The forged bars used in this work were tested in the annealed condition; little is known concerning the effect of forging practice on ductility in titanium metal.

Jan 1, 1952

By M. G. Ayat, B. C. Scott

H. P. Ferri I refer to the article "Degradation Process in Coal Slurry Pipelines" by M.G. Ayat and B.C. Scott in the September 1988 issue of Mining Engineering. I would like to congratulate Dr. Ayat and his colleague on a very interesting and valuable piece of work. This article is an excellent one, describing a real phenomenon that has been ignored for so long. I do, however, have an objection. The article fails to address the degradation process when coal is processed or transported in other ways than slurry form, particularly those employed in this work. Could, for example, screening (wet or dry) have contributed to the extent of degradation? Perhaps scanning electron micrographs of the samples examined and after screening would have helped to clarify this. I would like to point out that degradation is also observed in pneumatic conveying systems, mechanical conveying, and other means of transportations employed by the mineral industry. Reply by M. G. Ayat We gratefully acknowledge Dr. Fern's comments on the subject paper. As he so rightly points out, the degradation process is a real problem, not only in coal slurry pipelines, but also in many handling and processing equipment employed by the coal and mineral industry. Scanning Electron Microscopic examination of samples may offer very little information about the extent of degradation for several reasons. One is that preparing a representative sample that has undergone degradation will be extremely difficult if not impossible. This problem is exacerbated by the fact that SEM requires only very small amounts of material for testing. Secondly, there is a sample preparation step involved in the SEM examination and, as such, it would be very difficult to associate the extent of degradation to either sample preparation or handling and processing operations. Finally, it is probably worth mentioning that degradation is a multi-faceted phenomenon involving many natural and man-made factors. The logical approach to this problem would, therefore, seem to be a "one-step-at-a-time" approach.

Jan 2, 1989

By Sharwood M

Welcome to the morning of the second day of Minval '89. There are some three hundred and fifty of us here today. That represents certainly the most influential gathering of the mining and investment community in Sydney for a very long time, and on behalf of the Institute I bid you all a very great welcome. Due to the pilots' strike some of you have arrived by very unusual methods and others have travelled long distances. So for those of you that have made a special effort, thank you very much. Inevitably some people have not been able to get to Sydney and this has led to some minor programme changes. I'd like to thank our sponsors. Our underwriting sponsors are Energy Resources of Australia, Neil Cole & Associates, Resource Finance Corporation and Robertson Australia Limited, and to those firms thank you very much. To our major sponsors, County NatWest, I would like to say a particular thank you. County is the lead sponsor for Minval '89. They've :made an important contribution to the programme, and we're indebted to them for this support. We look forward to County's continuing involvement in the programme today. County NatWest is a major participant in the Australian equities markets and a growing merchant banking organisation in this country. It's parent organisation, National Westminster Bank, isa leading UK domiciled bank which is also active in Australia. This session is the Pancontinental Mining Ltd sponsored session, and I'd like to record the gratitude of the Australasian Institute of Mining and Metallurgy to Pancontinental for its generosity in sponsoring the session. This morning's session focuses on valuation and follows on from yesterday's proceedings which looked particularly at the impact of NCSC draft Policy Release Number 149. Robert de Crespigny, who was to have been the Chairman of this morning's session, has had some special problems with the pilots' strike.So we have the privilage to have in his stead Michael Sharwood.

Jan 1, 1989

By F. R. Wadleigh

It is generally realized and very often admitted by both producers and consumers of coal that there is great need for a revision of existing commercial classifications, and this will involve, of course, determination of a standard classification and a constant revision of marketing practices as they are affected by coal classification. I recently sent out some 200 letters to producers and consumers with a request for their views on the subject of commercial classification. Nearly all of the replies from both sides were that there was needed some change in the present method. There were three or four dissenting voices but the great majority of opinion was in favor of the formulation of some standard commercial classification. The classifications in commercial use today can best be described as a hodgepodge. They are made upon different bases, have different names and have different ways. There are, for instance, about 11 single bases of classifications as used commercially and some 17 or 18 combination bases. Then there were the Tidewater Pool Exchanges. The classification which they put in force is still used in the tidewater markets and has several different bases of its own. It will be considerable of an undertaking to bring about a change in marketing methods as affected by coal classification but it is well worth doing and I think the committee which has been appointed under the auspices of the American Society for Testing Materials realizes the importance of the subject and is on the way to at least bring about some provision for adjusting matters. By way of starting, each member of the Committee on Commercial Classification has been assigned to a general market district and each member is now engaged in collecting the commercial market practice data for submission at the next meeting of the Committee. About a year ago I made up a list of the commercial classifications in the different markets and the total was 171. The 11 single bases I found used in commercial practice were:

Jan 1, 1930

By R. C. Kirkman

Your interesting and well-written paper brings up the issue of the purpose or use of a mineral property appraisal, specifically the value of these evaluations when the quality and quantity of the mineral resource to be exploited have not been thoroughly investigated. I am not a practicing professional in regards to valuation of limestone investment opportunities. I simply wish to make a few generic observations about the appraisal process in order to stimulate meaningful thinking by appraisal professionals whose reports may be reviewed by professional investors and "laypersons" alike. It is my contention that the analysis given in your paper is very thorough, considering the data that was made available to you. But I would not like to be the person responsible for investment decision making without having a feel for the risk involved. Therefore, the reviewer must classify this type of analysis as relatively "subjective" because they have not received an indication of the inherent risk involved in exploiting a mineral resource. This risk can best be quantified by using probabilistic methods in conjunction with the quality and quantity of the mineral to be produced. Most appraisals passively ignore this problem. Specifically, you have accurately identified the various costs and values entering the economic appraisal process. These can usually be quantified with a great deal more certainty than the capability of the resource to provide 25 years of quality material. Also, in Cases A (West Virginia)and B (Alabama), you are fortunate enough to have previous operations data. What if there had never been production from these properties? How does a potential mineral property investor evaluate the resource capability to meet various projected financial outcomes without spending a good deal of up-front capital to drill and delineate enough quality resources for a 20-plus year operation. These questions pose a substantial risk to any potential mineral investor. Only probabilistic methods should be used to quantify this type of problem, short of drilling and metallurgical testing. I might be considered a "layperson," not being familiar

Jan 1, 1991

The Carol concentrator of the Iron Ore Company of Canada was completed in 1962 and through expansions .has become one of the largest iron ore beneficiation plants in the world with a new feed capacity of 147,000 It (149,350 mt) per day. The Carol ore contains specular hematite and magnetite having a bulk density of 166 lb/cu ft (2660 kg/m3) It is crushed to 7 in. (178 mm) for feeding to autogenous mills for subsequent concentration by Humphrey’s s spirals. Mine ore is loaded into 150 It (152 mt) trucks by 10 cu yd (7.65 m3) shovels and then, at a transfer station, is loaded into side-dump rail cars of 100 It (101.6 mt) capacity. Each train is composed of twenty cars and operates completely automatically as it hauls the ore to the primary crushing station, dumps its loads, and returns to the loading station, a 11.5 mile (18.5 km) round trip. The primary crushing station is composed of two 60 in. by 89 in. gyratories installed in 1962 and 1972. Neither crusher has a grizzly ahead of it. Rail cars are dumped into 300 It (305 mt) pockets which contain splitters for spider protection. What few oversize boulders which do not go through the crushers are drilled and blasted. Liners in the dump pocket and the crushed ore pokcet under the crusher are manganese steel. Both crushers are direct driven by 700 hp (5 15 kw) motors, and the hardness of the ore causes them to pull almost their full power. Crushed ore drops into a 160 It (163 mt) pocket equipped with radioactive level control units for low-intermediate, and high level indications. The low level unit stops and starts the apron feeder, the intermediate unit controls the feeder speed, and a high-level reading stops the car dumping. Apron feeders are 72 in. (1. 82 m) wide and are variable speed from 12 to 52 fpm (3. 7 to 15. 8 mpm). They discharge to 60 in. (1.52 m) wide takeaway belts. Crushing capacity, nominal and maximum for each crusher, is 4, 000 ltph (4. 064 mtph) and 4,600 ltph (4,674 mtph). The crusher eccentric is removed by a conventional cart which travels on removable rails. Mainshaft removal and maintenance is done by 65 and 75/10 ton cranes. Mainshaft replacement requires eight hours, a usual time, but concave replacement requires only sixteen hours, a result of a fine maintenance organization. Mantle relining is done at grade next to a repair track. Zinc is used for backing both mantles and concaves. Both the electrical rooms and the dust collectors are located below grade,

Jan 1, 1978

By George Schipper, Peter Gelten, Pepijn Adriaen, Hugo Uijtdebroeks

Tata Steel IJmuiden Hot Strip Mill 2 (HSM2, 5.5 Mtonnes/yr) is currently being upgraded, resulting in an increased rolling force and motor power capacity. With the current conventional work roll spray cooling, a deterioration in work roll & strip surface quality performance is expected as a result of the increased mill capacities. In order to improve strip surface quality, HSM2 decided to do a full-scale production trial with High Turbulence Roll Cooling (HTRC) at stand FM2. HTRC is a novel way of roll cooling using a high turbulent flow regime. HTRC is positioned very close to the roll surface and gap exit, which is beneficial for the roll surface quality. It is operated at a high flow rate but at a low pressure. HTRC not only significantly improves the roll surface quality, in addition, it makes high pressure pumps, needed for the conventional spray cooling, redundant, leading to substantial savings on electricity costs and thus CO2 emissions. HTRC is in trial operation since 7 August 2018. Results show no operational issues, an excellent roll surface quality and an increased cooling efficiency. In summer 2020 stands FM1-FM2-FM3-FM4 of HSM2 will be equipped with HTRC.

Oct 1, 2019

By R. D. Carpenter, R. R. Smith, E. E. Sougstad

The Union Carbide Nuclear Co., in treating low-grade tungsten and molybdenum-copper ores at the Pine Creek mill near Bishop, Calif., employs flotation for the initial extraction of the valuable mineral constituents. These minerals consist of scheelite, molybdenite, and several of the copper sulfides including chalcopyrite, bornite, and possibly chalcocite. They occur in a gangue consisting mainly of quartz, pyroxene, and garnet, with minor amounts of calcite and fluorite. This assemblage of minerals presents an unusual grinding problem because of their diverse physical characteristics. Feed for the circuit is prepared from -6-in. ore by screening on a rod deck screen to remove the -5/8 - in. material. The+5/8-in. fraction is crushed in open circuit with a 5 1/2-ft Symons shorthead crusher operated at a closed- side setting of approximately 3/8 in. The screen undersize and the conecrusher discharge are then combined to constitute the feed to the grinding circuit. The ore is ground in 6 by 5-ft grate discharge ball mills operated in closed circuit with 54-in. spiral classifiers. The classifier overflow goes directly to the flotation section of the plant. Studies of the flotation circuits have shown that the maximum recovery of the tungsten, molybdenum, and copper minerals occurs in the particle-sue range from 100 mesh to approximately 400 mesh. Further, practice has shown that the ore minerals are effectively reduced to this size range if the total ore is ground to -48 mesh. The general objective of the grinding circuit then is to reduce the feed to -48 mesh with the production of a minimum amount of slimes. The purpose of this investigation was to ascertain how well the grinding circuit was carrying out this objective. The method used was to sample the various products in the grinding section, size these products accurately, and analyze the resulting sue distributions. SAMPLE PREPARATION AND SIZING TECHNIQUES Representative samples of the different grinding circuit products, namely, new feed to the ball mill, ball mill discharge, classifier overflow, and classifier return, were taken over a 24-hr period. The samples were then dried without being filtered to avoid loss of slimes. The percentages of solids in the different products were the following: new ball-mill feed, 95%; ball mill discharge, 82%; classifier overflow, 52%; and classifier return, 84% solids. Particle sizes were determined on each product by wet-screening an

Jan 1, 1962

Throughout the 1970s, the US Bureau of Mines rode an ebb tide in Washington political circles. In rapid fire succession, the agency lost its mine health and safety enforcement responsibility (1973), a large portion of its energy research responsibility (1975), and then its fuel statistics functions plus a sizable portion of its coal R&D (1977). By 1978, johnny-come-latelies in the Energy, Labor, and Interior Departments had siphoned away from the Bureau some $125 million in program responsibilities as well as 900 of its employees. The bruising decade came to a close with a Department of Natural Resources proposal that, in its original form, would have scattered the Bureau's responsibilities to the winds. "There is no doubt in my wind," said Lindsay Norman, acting director of the Bureau of Mines (see box), "that were the Bureau to continue down the path it was on, the next step was closing the doors and going out of business." The doors are still open, but erosion of responsibilities had a devastating effect on the resources available to fulfill the Bureau's mission. Devastating, too, in terms of internal morale, considering the Bureau had six directors in a 10-year span. "When the troops are in the trenches and are being shot at," Norman said, "they need a leader-hopefully, a permanent one- that can get them advancing. This is something the Bureau did not consistently have in the 1970s." In September 1978, Roger Markle climbed aboard as director of the Bureau to rejuvenate the 70-year-old agency. He resigned only six months later* but the program Markle set in motion is being carried through by Lindsay Norman. Since Norman's appointment as acting director, he has spent considerable time on the road explaining his agency's redefined goals. At one such stop in Duluth, Norman and his two deputy directors, Charles Kenahan and Mike Kaas, answered the following questions. Lindsay, you were the principal architect in the Bureau's 1979 reorganization. How about a glimpse of what that entailed? Toward the end of the 1970s, after almost a decade of steady dismemberment, we reached what we felt was a critical point in the Bureau's history-we had the choice of redefining and strengthening our organization to meet the mineral challenges ahead, or continuing down the path toward the agency's eventual demise. We felt the Bureau's mission too important to abandon, so in 1978 with Roger Markle as director we initiated a six-month, no-holds-barred intro spection of just what the Bureau should be doing, why, and toward what ultimate national needs. And what did this self-reflection reveal? That there is, indeed, a unique federal role for the Bureau of Mines-that of a lead agency for influencing mineral decisions and pioneering tomorrow's technologic advances. Don't confuse us with policymakers, we're not. But we are policy analysts; we're scientists, engineers, and mineral professionals who can offer a sorely needed source of objective, accurate information to decision makers in both the public and private sectors. I feel there is no better brain trust in government than the Bureau when it comes to mineral expertise-of course, I'm biased. Do I understand you to say the Bureau of Mines is an advocate agency for the minerals industry? We plead no parochial interests, nor ought we, but from our viewpoint a sound minerals industry is extremely important to the broader national goals of security and a healthy economy. US dependence on foreign sources for critical minerals, the increasing noncompetitiveness of some US mineral sectors, and the array of land use issues surrounding mineral-rich lands all have much more serious implications than many otherwise informed people seem to recognize. In your estimation, how vulnerable is the US to foreign mineral suppliers? Let me make a distinction between dependency and vulnerability. The

Jan 4, 1980

This Workshop was held at the Doubletree Inn, Seattle, Washington from September 26 to 28, 1997. Run under the auspices of the Deep Foundations Institute (DFI), it was co-funded by the newly formed Japanese Association of Micropiles (JAMP), and the Federal Highway Administration (FHWA). The Workshop was jointly organized and facilitated by Fujita Research Corporation and ECO Geosystems, Inc., with close support by Donald B. Murphy Contractors, Inc. DFI kindly consented to publish these Proceedings. As is clear from the list of attendees, 42 specially invited engineers from all aspects of micropile technology were present, representing Japanese, European and American practice. This proved to be a most friendly and interactive group of people, who freely exchanged ideas, views and close comradeship, not only during the technical sessions, but (and especially!) during the numerous social events. Perhaps the best illustration of this came in Day 2 when the attendees were divided into five competing teams, each comprising representatives from the different geographic groupings. These teams had to quickly devise solutions to two technical problems (using standard data previously provided. A team of "referees" (who also acted as "coaches") later determined the most apposite response, based on constructability design concept, cost, schedule and so on. Not only were the winning team very liberal in distributing the prize (vintage California champagne) among themselves, but the whole Workshop soon benefited from their generous division of the spoils of victory.

Jan 1, 1997

The completion of the 3rd expansion at Queensland Alumina added 725,000 t.p.y. capacity to what was already the world's largest alumina refinery. Rated design capacity is now 2.0 million t.p.y. The expansion was achieved by adding a separate liquor circuit, interconnected with the old at strategic points. This effectively linked a new facility to the existing plant. The resultant problems in controlling plant flow highlighted problems which required considerable operator retraining. The process control problems caused by an inexperienced work force are discussed as are some of the solutions now under study at Q.A.L.

Jan 1, 1974

By P. T. L. Koh

The effect of particle shape on the flotation process has been investigated in laboratory experiments with monosized spherical ballotini and roughly ground ballotini. The particles were treated by partial methylation with trimethylchlorosilane to achieve varying degrees of hydrophobicity. In flotation, the process of film thinning and liquid drainage is critical in the formation of a stable bubble-particle attachment and this is affected by the particle shape and surface hydrophobicity. The rate of attachment affects the overall flotation rate. Flotation tests with different particle sizes at various degrees of partial methylation have been performed in a modified Denver cell. Predictions from a computational fluid dynamic model of the cell which incorporates fundamental aspects of bubble-particle attachment are compared against flotation test results. Contact angles of the particles have also been measured using the capillary rise technique to indicate surface hydrophobicity.

Jan 1, 2014

By A. Muan

Liquidus data are presented for mixtures in the ternary system FeO-Fe2O3-SiO2 in equilibrium with a gas phase with O2 pressures ranging from 10-10.9 to 1 atm. Data obtained are combined with previously published data to construct lines of equal 02 pressures and lines of equal CO2/H2 mixing ratios along the liquidus surface. Courses of crystallization of selected mixtures under conditions of constant total composition, constant O2 pressures, and constant CO2/H2 mixing ratios are discussed. PHASE equilibrium studies of silicate systems where iron is one component are complicated by the fact that iron readily occurs in three different states of oxidation: Fe3+, Fe2+, and Fe0. Success or failure in work with iron silicate systems is to a large extent dependent on control of the oxidation state of iron and all investigations therefore must be carried out under carefully controlled atmospheric conditions. Silicate systems containing only strongly electropositive metals (like Na+, Ca2+, Mg", etc.) can, for simplicity, be treated as condensed systems, that is, the gas phase can be neglected and the phase relationships discussed in terms of the phase rule written in the well known simplified form P + F = C + 1. In the case of iron silicate systems, however, the composition of the condensed phases varies with the gas composition, and a complete picture of phase relationships can be obtained only by varying the gas composition over a wide range. In order to understand the phase relationships in the more complicated multicomponent silicate systems with iron oxide as one of the constituents, a knowledge of the ternary system FeO-Fe2O3-SiO2 is essential, since it constitutes a bounding portion of all such systems. It was with this in mind that the present study was undertaken. Previous Work A considerable amount of work has been done on various aspects of the chemistry and metallurgy of systems containing silica and iron oxides. The two bounding binary systems FeO-Fe2O3 and FeO-SiO2" The first attempt to obtain information on phase relationships of iron oxide-SiO, mixtures at different 0, pressures was made by Greig.' Darken" determined the melting points of iron oxide on solid silica under various atmospheric conditions. Darken did not determine experimentally the composition of the melts at liquidus temperatures but discussed very ably the principles involved in applying the phase rule to the system. In a recent study Schuhmann, Powell, and Michal8 determined experimentally the liquidus surface of a portion of the ternary system and combined the new information with data in the literature to construct a phase diagram. Their method was briefly as follows: Homogeneous mixtures with various contents of SiO2, FeO, and Fe2O3 were made up by melting together stock mixtures in various proportions. Samples of the homogeneous mixtures, the compositions of which were determined by chemical analysis, were then heated in platinum crucibles in an inert atmosphere until equilibrium among the condensed phases was achieved. The samples were quenched to room temperature and the phases present determined by microscopic examination. Assuming that no change in composition takes place during the equilibration run in inert atmosphere, the liquidus surface can be determined, but no information is obtained regarding the partial pressures of 0, of the gas phase in equilibrium with the condensed phases. The author's method, to be described in the next section, permitted the location of points at the liquidus surface as well as a calculation of the corresponding partial pressures of O2. Experimental Method General Procedure: The standard quenching technique was adapted for a study under controlled variable atmospheric conditions. Premelted mixtures of silica and iron oxides in platinum envelopes were held at constant temperature under chosen atmospheric conditions until equilibrium was reached among solid, liquid, and gas phases. The sample was then quenched to room temperature, the phases present identified, and, for the most significant runs, the composition was determined by chemical analysis. The corresponding partial pressure of 0, was calculated from known equilibrium constants of the gas reactions occuring in the furnace atmosphere. Materials: Starting materials were oxides of commercially highest available purity; cp silicic acid was dehydrated by heating to 1350°C for 6 hr and cp Fe2O3 was dried at 400° C for the same length of time. Samples of 10 g were made up by mixing

Jan 1, 1956

By C. T. Cox

W. A. Reich.*—I should like to ask Mr. Cox if he has any information on the change in

Jan 1, 1945

By Henry P. Chandler

Tripoli is the general name for a number of fine-grained, lightweight, friable, minutely porous, forms of decomposed siliceous rock, probably derived from siliceous limestones or calcareous cherts. Tripoli is often confused, both in the trade and technical literature, with tripolite, a diatomaceous earth (diatomite), found in Tripoli, North Africa. A material found near Seneca, Mo., resembling tripolite was incorrectly termed "tripoli." This name has persisted and now has a definite physical and trade meaning. However, tripoli contains no diatoms, is of an entirely different origin, and has chemical and physical properties different from those of tripolite. There are two distinct types of tripoli in the United States; that from the Missouri-Oklahoma field and that from the Southern Illinois field. Commercially the term "tripoli" is applied to the material from the Missouri-Oklahoma field, while the material from the Southern Illinois area is often referred to as "amorphous" or "soft" silica. Material similar to the Missouri-Oklahoma tripoli, but finer grained, occurs in northwestern Arkansas. In its Minerals Yearbook the Federal Bureau of Mines groups statistically under "natural silica abrasives," tripoli from these producing areas and rottenstone from Pennsylvania. The justification for this grouping is the similarity of use. Composition and Physical Properties Commercial tripoli contains 97 to 99 pet SiO2. The remainder is mostly alumina, iron, lime, soda, and potash, some of which may impart desirable physical properties to the material. Variations in the chemical composition of tripoli are not as important as its physical characteristics. The color of tripoli varies from white to cream, brown, rose, and red, the variations from white being the result of iron deposited from percolating surface waters. The commercial varieties of tripoli mined in the Missouri-Oklahoma area are designated as cream and rose. Other physical properties of the tripoli from this area are: Free quartz, less than 0.5 pct; oil absorption, 50.71 to 53.14 pct; water absorption of the crude tripoli, about 38 pct, and of prepared material, about 52 pct; fracture, uneven to conchoidal; specific gravity, 2.15 to 2.62; weight per cubic foot crude, 35 lb, ground, 55 lb; fusion point, 3,225° to 3,300°F; and refractive index, 1.54. Tripoli occupies about 1 cu yd to the short ton in place and about 1.5 cu yd when broken. Packed for shipment, the powdered material occupies about 33 cu ft to the ton. Its value and usefulness depend primarily on a low content of crystalline silica, size of the natural particles, absorption, and color. Some beds in the Missouri-Oklahoma area are of sufficiently compact material that large, fairly strong blocks may be removed. These find a market as filter blocks and have been used for building material. In the Southern Illinois field the color of the material is the important physical property; pure white is preferred. The rottenstone mined in Pennsylvania is of higher density and lower in silica content than the various types of tripoli. Its composition approximates 60 pct silica, 18 pct alumina, 9 pct iron oxide, 8 pct alkalies, with small amounts of lime and magnesia. The material apparently is a ferruginous and siliceous shale, having properties rendering it suitable as an abrasive or as a filter for paint, rubber, and plastics.

Jan 1, 1960

By S. N. Groudev

A process for the combined chemico-biological removal of iron present as oxide minerals in different mineral raw materials (quartz sands, kaolins, clays, etc.) was developed. In the process, mineral raw materials are leached at about 90 °C with lixiviant containing microbially produced oxalic and hydrochloric acids. The leaching is carried out in mechanically stirred acid-resistant reactors for periods of from 1 to 6 hours, depending on the iron content and the forms of iron in the raw materials being leached. The iron contents of some sands treated by this method were lowered from levels that were in the range of 0.035% to 0.088% Fe2O3 to less than 0.012% Fe2O3, making them suitable for the preparation of high-quality glass. The iron contents of different kaolins were lowered from levels that were in the range of 0.65% to 1.49% Fe2O3 to levels in the range of 0.44% to 0.75% Fe2O3. As a result, the whiteness was increased from values of 55% to 87% to values of 86% to 92%. The iron content of clay was lowered from 6.25% Fe2O3 to 1.85% Fe2O3, and this increased the “fireproofness" of the clay from 1,670°C to 1,750°C. A similar process was used for the leaching of aluminum from aluminosilicates, mainly clays and kaolins. However, in this case, the microbial fermentation fluid containing citric acid was acidified by means of sulfuric or hydrochloric acid or by means of different mixtures of mineral acids. For enhancing aluminum solubilization, the aluminosilicates were heated before leaching at 600° to 650°C for 1 to 2 hours. Over 90% of the aluminum present in different clays and kaolins were leached within 3 to 6 hours. "Silicate " bacteria related to the species Bacillus circulans were used to leach silicon from low-grade bauxite ores containing aluminosilicates as impurities. The bacterial action was connected with the degradation of the mineral structures (by means of microbial metabolites such as organic acids and exopolysaccharides), as well as with the selective separation of the rich-in-aluminum fine fractions, which were retained by the mucilaginous capsules of the bacteria. The solid residues after treatment were characterized by higher values of alumina and silicon module (A1203: SiO2 ratio), and they were suitable for processing by means of the Bayer process for recovering aluminum. The bending strength and other ceramic properties of kaolins were improved by contact with well-developed cultures of "silicate" bacteria. The improvement was caused mainly by bacterial metabolites (exopolysaccharides) that acted as resins during drying.

Jan 1, 2000

By Pascoal Ferrari Pedrosa

Neste trabalho é apresentado os resultados de um estudo experimental com tijolos de solo-cimento vazado, com diferentes adições de resíduos de borracha vulcanizada oriundas da indústria de recauchutagem de pneus. Foram realizados ensaios de caracterização do solo utilizado, das composições desse solo com resíduos de borracha e das misturas de solo-cimento produzidas com essas composições. Conforme os resultados de ensaios realizados em corpos-de-prova cilíndricos e em tijolos de solo-cimento, verificou-se que: ainda não é possível a introdução do resíduo de borracha de pneus de pneus em blocos de solo-cimento, pois não atendem características da NBR-10834 [4] e precisam ser melhor avaliados.

Aug 16, 2017

By Alexander V. Epiforov, Stanislav V. Balikov

This paper describes of processing tests of 8 flotation concentrates containing precious and base metals by pressure oxidation (POX) method. Concentrates 1 and 2 were gold-copper concentrates. Zinc and silver were by-products in these concentrates. These concentrates were processed by POX with following cyanidation of POX solid residues, copper solvent extraction and zinc carbonate precipitation. The recoveries of gold, copper, silver and zinc from these concentrate were 98, 99, 30 and 99%, respectively. Concentrates 3 and 4 were lead-zinc concentrates. Silver was by-product in concentrate 3. Gold, silver and copper were by-products in concentrate 4. Concentrate 3 was processed by POX with following reduction smelting of POX cakes for primary lead recovery and zinc carbonate precipitation from POX solution. The recoveries of lead and silver into ingot were 96 and 98%, respectively. The recovery of zinc was 99%. Concentrate 4 was processed by POX with following zinc carbonate precipitation and reduction smelting of POX cakes. Copper was precipitated from the POX solution using sodium sulphide prior zinc precipitation. The recovery of zinc into carbonate concentrate was 99%. The recoveries of lead, gold and silver into lead bullion were 95, 99 and 98% respectively. The recovery of copper into sulphide concentrate was 99%. Concentrate 5 was gold-pyrite concentrate, and concentrates 6-8 were double refractory gold-arsenopyrite concentrates. Silver was by-product in these concentrates. These concentrates processed by POX and CIL. The recovery of gold from concentrate 5 was 98%, and from concentrates 6-8 was 85-90. Low gold recovery from concentrates 6-8 was associated with preg-robbing factor. The recovery of silver from gold-sulphide concentrates did not exceed 10-20%. The low silver recovery was associated with argentojarosite formation that is resistant to cyanidation. The flowsheets for complex processing of precious and base metals sulphide flotation concentrates based on this test work results were proposed.

Jan 1, 2018

By Z. S. Abisheva

Rare and rare earth metals use quite often is an indicator of national economy development. The world structure of the rare-earth metals manufacturing countries in 2015 was presented as follows: China – 94.2%, India – 2.0%, Russia – 1.8%, the USA – 1.2%, Brazil – 0.5%, Malaysia – 0.3%. In Russia, large reserves of rare-earth metals, which reach nearly 28 million tons, are revealed. Kazakhstan, possessing a raw materials source of rare-earth metals, has all prerequisites for development of branch. Rare metals are manufactured in Kazakhstan incidentally by non-ferrous metals production. The production of indium, thallium, cadmium, selenium, tellurium, bismuth is made at the Ust-Kamenogorsk lead plant; tantalum, beryllium, niobium and molybdenum – at the enterprises of “National Atomic Company Kazatomprom” JSC. Production of a titanium, magnesium and vanadium is adjusted on “Ust-Kamenogorsk Titanium-magnesium Plant” JSC. Capacities for beryllic production yield are available on “Ulba Metallurgical Plant” JSC. The main producer of perrhenic production and osmium-187 is "Zhezkazganredmet" RSE. The single producer of gallium in Kazakhstan is “Aluminium of Kazakhstan” JSC; the capacity of enterprise is 25 t a year. In Kazakhstan innovative technologies for rare and rare earths mineral raw materials processing are created. The technology has been developed and a vacuum distillation apparatus has been created to purify crude selenium, which makes it possible to obtain a metal with a main component content of 99.9-99.99%. Technologies for processing of technogenic wastes and byproducts of the copper industry are developed. Implementation of technologies allow to obtain ammonium perrhenate, perrhenic acid, osmium isotope -187, tribasic lead sulphate, silver-concentrate. The technology of complex processing of black shales of Balasauskandyk deposit with the production of gold, vanadium, rare earth elements, uranium and ferrosilicon has been proposed. The processing was carried out using methods of autoclave leaching, sorption, extraction, precipitation. A highly profitable sorption technology for recovery of rhenium from solutions of underground leaching of uranium ores containing 0.2-0.4 mg/L of Re has been created. The organization of ammonium perrhenate production from solutions of uranium ore will significantly increase the volume of its production in Kazakhstan.

Jan 1, 2018