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By T. McWaters

In 1911, Miami Copper Co. began a block caving operation at its Miami, AZ property. A gravity mill was used to separate copper minerals from the Pinal Schist host rock. Until 1932, the mill tailings were deposited by the upstream method using perimeter launders and spigot valves in six canyons adjacent to the mill. In 1928, the larger and more distant Solitude tailing pile was developed. By 1932, it was receiving all tailings. In 1925, Miami Copper converted the gravity mill to flotation with sulfide copper recoveries. From 1934 to 1943, Miami, Copper ran a leach-precipitate float (LPF) circuit on mined ore and, in 1943, began sulfuric acid in-place leaching of a portion of the caved area formed by block caving. The pregnant solutions were collected underground and pumped to the LPF precipitating drums to harvest copper. In 1954, the company started mining low-grade ore. This led to the running an old LPF plant on select mill tailings from April 1957 to March 1959. In 1959, block-cave mining ceased. Solution mining became the only source of production using a launder precipitation plant. In the mid-1960s, Miami Copper merged with the Tennessee Corp. In the latter part of the decade, Cities Service Co. bought the combined properties. In 1976, Cities Service commissioned a 15-t/d (16.5-stpd) solvent extraction electrowinning(SX-EW) facility at its Miami copper property to replace the precipitation plant. In 1982, Occidental Petroleum Co. bought Cities Service. In 1983, the Miami operations were sold to Newmont Mining Corp. and set up as a subsidiary company, Pinto Valley Copper Corp. Finally, in 1987, Newmont Mining spun off a combined Pinto Valley and San Manuel unit as Magma Copper Co.

Jan 1, 1990

By F. F. Aplan

Mineral process engineering is a small but important part of the nation's raw material industry. Minerals are usually processed in large plants of high capacity, at low cost, using few engineers and operators, and at an ever-increasing level of plant sophistication. The magnitude of the mining industry is huge, with about 4 Gt (4.5 billion st) of ore, coal and industrial minerals mined annually in the United States. Industries such as construction, manufacturing and power generation rely heavily on a strong US resource base to maintain a competitive edge. Though rooted in classical chemistry, geology, physics and mathematics, a mineral process engineer must be trained in the science and engineering required to process raw materials. A modern mineral processing program still stresses the traditional aspects of the profession. But it also emphasizes particle technology, applied surface chemistry, chemical processing of ores, solid-fluid separations, process and equipment modeling and optimization, materials handling, personnel management, maintenance and environmental and health aspects. In such areas as particle technology and some aspects of applied surface chemistry, mineral processing academic programs have taken a leadership position in supplying specialists to a variety of other industries. The objectives of a mineral processing program are: • to furnish personnel to support the basic raw materials industries (undergraduate programs); • to provide a research and development base for industry (graduate programs); and • to provide expertise in particle technology, applied surface chemistry and environmental programs for other industries (undergraduate and graduate programs). In the United States, mineral process engineering programs have historically been associated with mining and metallurgy departments. The recent movement of metallurgy programs away from primary processing towards materials science has created the need for a new accommodation.

Jan 1, 1992

ON July 2 the Krupp plant in Essen was occupied by the French. The City of Frankfurt, on the edge of the Mayence Bridgehead was surrounded by the French. French infantry and cavalry occupied some more towns in the Ruhr. These moves were apparently in the way of reprisals. The Bank of England on July 5 raised its discount rate from three per cent. to four, per, cent., the lower rate having previously prevailed for almost exactly a year.. The advance appears to have been inspired by the reserve ratio, but especially owing to the fact that the low rate in the London market had led to the out-flow of funds from there to other markets. Philip Snowden brought up again in the British .Parliament his motion in favor of the condemnation of the capitalistic system and the substitution of socialism. The motion was put to vote and was defeated by large majority, only the members of the Labor party voting for it. The Allies and the Turks finally came to an agree-ment at Lausanne, the Turks getting about all for which they asked. It would be tiresome to record the details. The main fact is that the Turks, after having been ejected from Europe in 1918, are now going to return. Russia agreed to the settlement respecting the Straits. The Soviet Government of Russia formulated and adopted, subject to ratification, a constitution for the United States of Russia, which appears to be patterned after the constitution of the United States of America and the unwritten constitution of Great Britain. The important thing about this seems to be that it definitely reunites the constituent parts of the old Empire, the semi-independence of the Ukraine being surrendered.

Jan 7, 1923

W. A. SCHLESINGER,* Denver, Colo.-Two problems are of great interest to the radium manufacturer at the present tine: The first is to perfect a process, more efficient and more economical, which is capable of treating a greater variety of ores. . Practically all the radium now manufactured in the United States is extracted from carnotite ores and these vary a great deal according to their location. The amount of sulfates contained in the ore is of particular importance, and any straight acid-leaching method, such as developed by the Bureau of Mines, becomes prohibitive when the ore contains more than 0.5 per cent. of sulfates, as the sulfates go into solution and naturally precipitate the radium as insoluble radium sulfate. Since the amount of ore obtained from any one claim is usually comparatively small, it is necessary to work a number of claims in different localities, and a process, in order to be commercially satisfactory, should handle all of these ores. In other words, it would be entirely unprofitable for radium manufacturers to employ any process which cannot treat any but sulfate-free ores. He must deal with carnotite containing appreciable amounts of sulfates, and must be able to work this in with the other ores. Carbonaceous ores from certain sections in Utah; which are known to contain as pinch as 1.0 per cent. and more of volatile matters, are prone to a, nitric acid-leaching process. The second problem relates to the treatment of concentrates. There is no doubt that a very large amount of low-grade ore, containing less than 0.75 per cent. uranium oxide, is available. It has been demonstrated that these ores can be concentrated, but there is still room for research

Jan 11, 1918

By W. Spencer Hutchinson

It is the purpose of this paper to describe a method used to determine the corundum contents of samples of hard crystalline gneiss containing both corundum and red garnet. A chemical analysis of the rock for alumina would not fix the amount of corundum became at least three other constituent minerals of the rock, mica, feldspar, and garnet, contain alumina combined with silica. Following are the principal minerals found in the samples, together with their specific gravity and hardness as given by Dana: The corundum occurred in crystals of a gray or bluish gray color, in minute grains and coarser up to 0.5 in., and no massive or block corundum was observed. The larger crystals were commonly quite slender, well defined, and the normal hexagonal form clearly developed. They lay with the structural planes of the gneiss, and sometimes appeared prominently in relief on weathered surfaces. In some cases these crystals had suffered partial or total alteration to mica, margarite, or other soft minerals, a condition illustrated by sample D, which appeared to be studded abundantly with corundum on the flat faces. Garnet, a striking feature of nearly all the samples, was present in small rounded crystals of a pink to red color. The samples were first broken to pass a No. 4 mesh screen. This was done with a hammer on an iron plate, particular care being taken to avoid the breaking of the crystals finer than need be to pass the screen. A portion of the sample weighing 500 g. was then taken and, with a little water added, was scoured round and round in an iron bucket with a wooden block, until the coarse crystals of corundum were cleaned of adhering pieces of mica. The bucket was then re-

Jan 1, 1914

By M. F. Trice

PYROPHYLLITE is a hydrous aluminum silicate (A12Si4O10(OH)2)1 that occurs in both the foliated and the massive forms. The foliated variety resembles talc in that it has a greasy feel, a pearly luster, perfect basal cleavage, and usually is white, although in some deposits apple green, gray, brown, russet, and nearly black specimens may be found. The massive deposits of pyrophyllite yield pearl gray to light tan aggregates, some of which are so friable that they may be crushed with the hands into a fine gritty powder. Frequently specimens of the massive variety are studded with crystals of radial structure. The mineral has a specific gravity of about 2.7 and a hardness of 1 on Mohs' scale.1 The chemical composition of commercial pyrophyllite reflects the mineralogy of the deposits, which, according to Stuckey,2 contain pyrophyllite and quartz, together with chloritoid, sericite, and a few other minerals of negligible importance. The latter, he says, "are noticed in but small quantities to the extent they might occur as accessory constituents of an igneous rock or as products of regional metamorphism or weathering. . . . Quartz is abundant everywhere except in the very best grades of pyrophyllite." Analyses of specimens from several deposits are listed in Table 1, showing that the silica content varies from 57 to 73 per cent and the alumina from 22 to 33 per cent. Oxides of iron and the alkaline metals are collectively present, with one exception, to an extent of about 1 to 1.5 per cent. SOURCES At present, North Carolina is the only commercial source of pyrophyllite, although the mineral has been found in small quantities in many parts of the world. The North Carolina deposits are in the "Carolina Slate Belt," which traverses the center of the state in a southwesterly direction. This

Jan 1, 1940

By Daniel J. Turk, William R. Banning, John Paterson, Thomas J. Weitz, Michael L. Clark

Introduction Pegasus Gold's Montana Tunnels mine is a large surface gold, silver, lead, and zinc mine located 37 km (23 miles) south of Helena in southwestern Montana. Milling operations commenced in late March 1987. The concentrator achieved full production in May that year after undergo¬ing several modifications and improvements. Production for 1988 is projected to be 2.48 t ,80,000 oz) of gold, 34.2 t (1.1 million oz) of silver, along with 8.5 kt (9400 st) of lead, and 22.6 kt (25,000 st) of zinc from lead and zinc concentrates. Mill throughput currently averages 11.7 kt/d (12,900 stpd), compared to the origi¬nally designed capacity of 11.3 kt/d (12,500 stpd). Cash production costs, net of bypro¬duct revenues for the third quarter 1988, were below $3.20/g ($100 per oz). The introduction of ore to the concen¬trator marked the culmination of 12 years ex¬ploration, evaluation, and development. Initial milling operations encountered diffi¬culties with the circuit as designed. As a result, several modifications and improve¬ments were made to the plant. This article is intended to assist other companies developing projects of this type and complexity. It discusses the mine's de¬velopment from feasibility and construction through start-up. The operation, as it exists today, is reviewed including the modifica¬tions and improvements made since start-up. History The mine is situated in Jefferson County, MT within the historic Corbin-Wickes min¬ing district. Underground mining began in 1864 and flourished until the early 1900s. Between 1864 and 1900 the vein deposits in the district produced about $41 million dol¬lars worth of lead and silver ores containing subordinate amounts of zinc, copper, and gold. At various times, three smelters were operated in the area.

Jan 1, 1989

Statistics compiled by the United States Geological Survey show that the iron ore mined in the United States in 1917 reached a total of 75,288,851 gross tons, exceeding the former record output of 1916 by 121,179 tons. The shipments from the mines in 1917 were 75, 573,181 gross tons, valued at $238,260,333, a decrease in quantity of 2,297,372 tons, or 2.95 per cent., and an increase in value of $56,358,056, or 30.98 per cent., over the shipments in 1916. The average value per ton at the mines for all grades of ore in 1917 was $3.15 as against $2.34 in 1916. Stocks of iron ore at mines, mainly in Minnesota and Michigan, amounted at the close of 1917 to 10,628,908 gross tons, compared with 10,876,352 gross tons in 1916. The quantity of pig iron, exclusive of ferro-alloys, sold or used in 1917, according to reports of producers to the United States Geological Survey, amounted to 38,612,546 gross tons, valued at $1,053,785,975; compared with 39,126,324 gross tons, valued at $663,478,118 in 1916, a decrease of 1.32 per cent. in quantity and an increase of 59 per cent. in value. The average price per ton at furnaces in 1917, as reported to the Survey, was $27.29, compared with $16.96 in 1916, an increase of 61 per cent. The production of pig iron, including ferro-alloys, was 38,647,397 gross tons in 1917, compared with 39,434,797 gross tons in 1916, a decrease of 4.5 per cent., according to figures published by the American Iron and Steel Institute, March 18, 1918.

Jan 12, 1918

The meeting of the Board of Directors, on November 22, was attended by eight directors, the Secretary of the Institute, and eight guests. The proposed James Douglas Prize and Tablet was referred to a committee of eleven. Robert H. Richards was appointed representative of this Institute to attend the meeting of the Society for the Promotion of Engineering Education. J. V. N. Dorr was made chairman of the Finance Committee in place of George D. Barron, resigned. The sum of $200 was appropriated for the 1918 expense of the American Engineering Standards Committee; the question of an appropriation for 1919 was referred to the Executive Committee for study and report. The sum of $50 was appropriated to the Treasurer's clerk. The following representatives of the Institute were elected: W. L. Saunders to succeed himself as United Engineering Society Trustee; R. M. Raymond to succeed himself as member of Engineering Foundation Board; S. J. Jennings to succeed himself as member of Engineering Council; George F. Kunz to succeed himself as member of Engineering Council; C. F. Rand to succeed himself as member of John Fritz Medal Board of Award; E. Gybbon Spilsbury to succeed himself as member of the Library Board. To members of the Canadian Mining Institute residing in Canada or Newfoundland, the privilege was extended to subscribe to the Bulletin at the price of $5. An invitation was extended to the Mining and Metallurgical Society of America to consolidate with the American Institute of Mining Engineers. The appointment of Engineering Societies' Employment Bureau was reported. Thirty-nine members and ten associates were elected. Two members were reinstated. Extension of time for the payment of clues was granted to four members. Seventeen members on active duty at the front had their dues remitted.

Jan 1, 1919

W. H. LINNEY, Chairman, OSCAR LACHMUND, Vice-Chairman LYNDON K. ARMSTRONG, Secretary-Treasurer, P. O. Drawer 2154; Spokane, Wash. STANLY A. EASTON, S. SHEDD. Mining camps from Mexico to Alaska and from the Pacific coast to the Atlantic were represented by delegates at the 5th Annual Northwest Mining Convention which was held in Spokane, Wash., Feb. 19-24, 1917. About 300 delegates from outlying regions were present, this being fully 100 more than have been counted at any previous mining convention in Spokane. Graham B. Dennis, president of the Northwest Mining Association, made the address of welcome. In part, he said: "Heaven has made us the possessors of an area great enough for an empire, varied enough in climate and possibilities to compass the whole complex field of modern industry. In the development of this broad heritage, we are not only actors for today, but trustees for future ages. "It is to foster this spirit of unity; to create and maintain strong bonds of mutual good will and confidence, that we founded the Northwest Mining Association. Wee support it because we believe it will give us strength; because we believe we shall learn from each other; because, in industry as in every other walk of life, personal contact and establishment of ties of friendship enrich and round out the characters of men." One of the interesting lectures of the week was that on "Alaskan and Russian Gravel Mining," by Dr.' Henry Mace Payne, consulting engineer for the Russian government and Consolidated Goldfields of South Africa. Dr. Payne's illustrations showed the different appliances in use in the countries mentioned. The Resolutions Committee reported back to the Convention six of the seven resolutions that had been presented to it. These were adopted as submitted, with some minor changes.

Jan 5, 1917

By G. H. F. Gardner

The boundary conditions F = 1.0 and 4 = 1.0 (100 per cent) are dictated by the definition of F in the equation 1/F = aFp. These conditions have physical significance as the "limiting conditions" for the observed behavior in systems of dispersed particles. The other boundary conditions, cited by Gardner in his Eq. 3 as applying to this system, have no significance in the systems we studied. Maxwell's equation (Eq. 2) cited in Gardner's comments was developed for and limited to a regular, rather than random, dispersion of spheres which are sufficiently removed from each other so that they do not interfere with current flow about their neighbors. These restrictions also apply to Rayleigh's analysis. The title of Rayleigh's paper cited by Gardner is "On the Influence of Obstacles Arrayed in Rectangular Order upon the Properties of a Medium". He is not discussing randomly dispersed spheres. It might be inferred from Gardner's comments that Rayleigh specifically considered the differential equation (Gardner's Eq. 3). This is not the case. Mathematically, Gardner's Eq. 3 is exactly true for the system to which it applies, however, as both Rayleigh and Maxwell note that their equation for F in terms of F is not for randomly dispersed spheres. At the time we wrote our paper, we were aware of the work of Wyllie and Gregory as cited by Gardner. We cited their work in Ref. 5 of our paper. Our comment on page 287 of the paper about the validity of an m value of 1.3 for spheres with a porosity of 38 per cent remains as our answer to Gardner's question on this point. Our data, at 38 per cent porosity, show that the condition a = 1 and m = 1.3 holds for spheres near 40 per cent porosity.

By J. D. Mooney, D. L. Darnell

The accompanying chart has been drawn for the convenicncc of engineers as' a means of quickly determining the correct number of plies of conveyor belts operating under specific conditions. The calculations are based on the average safe strength (factor of safety, 15) of the various standard rubber conveyor belts. The calculations assume maximum loading conditions; that is, the belt is considered as carrying the greatest load that it will handle without spillage at ordinary belt speeds. This not only produces the most economical operating conditions, but also the maximum tension in the belt. The chart is a graphical representation of the formula: Where, p = kg W(L + 10H) p = the correct number of plies k = a constant, depending on the type of drive g = the weight 'in pounds per cubic foot of material handled W = the width of the belt in inches L = the length of the belt in feet (approximately twice the center distance). H = the difference in elevation between the head and tail pulleys, in feet. For a simple drive, with a bare pulley, k = ----1 For a simple drive, with a rubber-lagged pulley, k = --- 1 For a, tandem drivej with bare pulleys, k = 1/375.000 For a tandem drive, with rubber-lagged pulleys, k = ---1 The chart is drawn for a simple drive, with a bare pulley (k — =e)1 ; therefore, the number of plies obtained from the chart should be multi- ' plied by the factor 0.83 or 5/6 for simple, lagged drive; the factor 0.67 or 2/3 for tandem, bare; and the factor 0.55 or 11/20, for tandem, lagged. The formula p = kgW(L + 10H) has been developed mathematically

Jan 1, 1916

By P Joyce, A S. Ray, P S. Thomas, J Haggman

Climate change and global warming present a significant challenge as unsustainable levels of greenhouse gas emissions arising from human activities continue to be emitted. The cement industry is responsible for between five and ten per cent of annual world carbon dioxide emissions; most arising from the manufacture of Portland cement (PC). An effective way of reducing emissions is by incorporating supplementary cementitious materials (SCMs) as partial PC replacements. SCMs are silicate or aluminosilicate based pozzolanic materials which, in finely divided form, combine with water and calcium hydroxide (lime), liberated by cement hydration, to form compounds exhibiting cementitious properties. Pitchstone is such an aluminosilicate and has the potential to act as an effective pozzolan for partial replacement of PC. In North Queensland, Australia, a vast deposit of pitchstone is mined and processed for expandable perlite aggregate. During the classification stage of the excavated natural material, waste pitchstone fines (PF) less than 0.5 mm in size are generated. This study evaluates the waste PF as a viable, eco-friendly pozzolan for the partial replacement of PC. The reactivity of the PF is compared to fly ash (FA), using the pozzolanic compressive strength activity index (SAI) after seven, 28, and 91 days ageing at 20 per cent and 40 per cent PC substitutions. PF was found to be comparable to FA as a pozzolan at 20 per cent PC substitution at all ages tested. However, for the 40 per cent substitution blends significant strength was only achieved at 91 days ageing for the FA blend. The pozzolanic reactivity was also investigated using thermogravimetric analysis to determine the degree of free lime present after 91 days. In all cases where an SCM was added, the free lime was observed to be consumed with increasing age.

Jan 1, 2008

By O. Guyot, T. Mulpeter

Sadiola Hill mine is located in the sub-Saharan part of Mali. In its first two years of operations, Sadiola Hill mine had already exceeded expectations with respect to profitability, plant capacity, metallurgical recovery, cash costs and social integration into the area. The advanced control system installed by the authors has been a major contributor in the substantial throughput of the mill over the design tonnage with no loss of recovery. The run-of-mine ore at Sadiola consists of soft clays with a varying percentage of grit, producing a high viscosity slurry. The percentage of grit fed to the plant varies on an hourly basis. This combination was expected to have a large impact on the milling circuit and determined that the early installation of an expert mill control system would be advantageous. Svedala Cisa OCS©, was selected as the most suitable support software. The operational rules and control philosophy are housed in the OCS© graphic-oriented fuzzy expert system while a model­based Soft Sensor has the remarkable ability to detect the variations in grit in the feed. Designed during the second half of 1996, commissioning of the system began in March 1997, the OCS was fully on-line by September. With the implementation of the optimising control strategy a throughput of 5.0 million tons relative to the target of 4.4 million tons was achieved for the 1998-operating year. The Sadiola project confirms that advanced process control techniques are among the most cost-and time-effective methods of improving metallurgical plant performance. The recipe that worked at Sadiola is a mix of metallurgical expertise, proper software selection, adequate design of control philosophy, and excellent plant support and follow­up. The early decision, design and installation of the mill control system has resulted in an enhanced Return on Investment.

Jan 1, 2000

By Avi Shonberg

With the advancement of offshore wind farm projects towards deeper waters and larger wind turbine generators, founda- tion solutions other than the monopile have received increasing attention over the past 5 years. Monopiles are the most commonly used foundation solution for offshore wind turbines, with 82% in European waters founded on monopile foundations (EWEA, 2019). However, 2018 saw a record number of suction bucket jacket (SBJ) structures, which consist of a three-legged jacket sup- ported by a suction bucket at each leg (Figure 1), installed for offshore wind. applications. SBJs have now been installed successfully at the Borkum Riffgrund 1, Borkum Riffgrund 2 and Aberdeen Bay offshore windfarms. Suction-installed foundations, referred to in this paper as suction buckets, suction caissons, suction piles or suction anchors, have been widely used in the offshore industry since the early 1980s for a range of offshore applications predominantly as anchors for floating offshore structures - where they are "the most widely used anchor types for deep-water mooring applications" (McCarron, 2011). Suction buckets, installed using pumps that generate suction forces by creating a pressure difference between the inside and outside of the bucket, allow for the installation to be undertaken with minimal noise and without the use of mechanical force. Therefore, a key difference between suction-installed foundations and other foundation types is that the installation design, which must consider the soil type, soil strength and installation specific risks (for example, soil stratification with significant differences in permeability) may have a direct influence on the dimensions of the foundation. While the number of SBJS installed for offshore wind applications has increased significantly in recent years, the installation process for SBJ struc- tures is yet to become standard practice and is considerably more complicated than the installation process for mon- opiles. This paper provides a brief

Jul 1, 2022

By David Wilburn

Recycled materials are increasingly being used in road construction to supplement natural aggregate derived from crushed stone, sand, and gravel. An understanding of the amount of substitution that is taking place, its economics, and factors affecting the level of substitution is useful in estimating the potential for recycling and in assessing the total supply of aggregate. While U.S. consumption of recycled aggregates from crushed concrete is estimated to have increased 160 percent between 1994 and 1996; it comprised less than 5 percent of total aggregates consumed in 1995. Construction waste supply is regional, and is determined by infrastructure decay and replacement rates. Aggregate recycling rates are greater in urban areas where infrastructure is being replaced, natural aggregate resources are limited, disposal costs are high, or strict environmental regulations prevent disposal. Recycling is expected to increase as construction contractors attempt to save on transportation, disposal, and new material costs. Aggregate producers include recycled material as an option to consumers in order to prolong the life of their reserves and improve their range of products. Recycled aggregates can be a supplement for natural aggregates in selected applications, but their use should be evaluated locally based upon relative cost, quality, and market factors Because aggregate recycling is often affected by local and regional transportation systems, disposal and tipping fees, resource supply, the market for specific products, and municipal support, costs for three representative fixed site operations of different sizes were modeled. Under study conditions, all were found to be profitable, but highly dependent upon local tipping fees and market prices, which can differ significantly by location. Smaller operations were found to have different operational dynamics, often requiring creative marketing or incentives to maintain profitability.

Jan 1, 2001

By D. M. Sloan

While surety capacity for the mining industry continues to shrink, States are demanding greater financial certainty for closure/post closure obligations. To combat these demands, larger mining companies are pursuing a Mining Surety Reinsurance Program that requires a significant up front capital contribution. This paper outlines an alter-native program for middle market mining organizations. The program utilizes a “Blended Finite Risk” environmental insurance solution with surety acting as the “front” in states where insurance is not an acceptable form of collateral. Marsh proposes creating separate programs for each State requiring surety. The reason for separate programs stems from each states’ different surety rules. Insurance companies typically require at least $5 million in future value remediation liabilities for finite risk programs. Since most middle market mining companies have obligations that fall below this threshold, the Blended Finite Risk Program contemplates combining several companies closure/post closure liabilities to accomplish the minimum amount required by the insurance company. Why use a Blended Finite Risk Program? One of the primary benefits is the financial assurance that funds will be available for planned remediation. For example, the financial assurance may be required by a government agency. The certainty may help facilitate a merger or acquisition. Additionally, the funds may be part of a CER-CLA PRP settlement. In all cases, the insurer providing coverage would be a secure independent 3rd party. A Blended Finite Risk Program also provides a long-term solution – up to 30 years and in some select cases longer. The benefit to a state or the BLM is the removal of financial uncertainty. An insurance company writing the policy would have an AA or AAA balance sheet. The hardening of surety markets coupled with the tightening of financial assurance requirements in many states have necessitated the posting of 100% collateral. This program substantially reduces these collateral requirements.

Jan 1, 2004

By H Aral, L Malishev

The carbothermic chlorination of titaniferous materials such as rutile, synthetic rutile (SR), upgraded slag and ilmenite in a fluidised bed is an established commercial process. In this work, ilmenite sourced from the Murray Basin area of South Eastern Australia was chlorinated and an assessment of the chlorination characteristics of the ilmenite, in terms of pre-treatment, type of reductant and reaction time was made. Selective chlorination of Murray Basin ilmenite to remove Fe and Mn was achieved in this work. A synthetic rutile sample containing around 93 per cent TiO2, one per cent Fe2O3 and 0.5 per cent MgO was produced at a chlorination temperature of 1000¦C with around 25 per cent loss of Ti as TiCl4. Raising the reductant to ilmenite ratio in the chlorination reactions increased the amount of Ti chlorinated. However, complete chlorination of Murray Basin ilmenite to produce FeCl3 and TiCl4, was not achieved under the conditions used in this work. Pre-oxidation of Murray Basin ilmenite before chlorination had little affect on its reactivity, compared with æas receivedÆ ilmenite. In contrast weathered West Coast ilmenite chlorinated appreciably better than West Coast primary ilmenite, in terms of bed residues remaining and amounts of elements removed. The presence of large amounts of Mg and chrome spinel grains in the Murray Basin ilmenite used in this study are likely to make it difficult to chlorinate directly in a commercial chlorinator. However, this is not to say these ilmenites will be unsuitable for chlorination applications. Further work is needed in the separation of Mg and chrome spinel grains from Murray Basin ilmenites and the products resulting from these tests could then be assessed in terms of chlorination performance, so that further processing options can be explored.

Jan 1, 2000

By R. B. Lincoln

THE function of a pyrometer protecting tube is to maintain an atmosphere about the thermocouple most favorable to its continued accuracy and long life, and at the same time permit the weld of the couple to attain the full temperature of the area or object being measured. In addition to protecting the thermocouple from the chemical or alloying effects of the products of combustion or bath being measured, the tube must also protect the couple from mechanical injury. The conditions met in practice vary so much that no one material is suitable for all applications. The usefulness as well as the expense of maintenance of a pyrometer system are influenced greatly by a choice of the most suitable protecting tube. The tube must protect the couple without itself becoming too great an expense item. The protecting tube should have the following qualities: (1) A melting point well above the highest temperature to be encountered. (2) Sufficient strength through the entire range of temperatures to hold up its own weight and resist such shock and jar as are unavoidable. (3) It must be impervious to the atmosphere or bath to which it will be subject. (4) It must not give off any vapor injurious to the couple. (5) It must not form any oxides fusible below the highest temperature to be measured. The proper location of the tube in the furnace is almost as important as the choice of material. The tube must be placed as near to the work to be heated .as possible. It must be kept out of the direct path of flame, both because that would give too high temperature readings and because partly burned fuel will destroy the tube faster than the quiet products of combustion.

Jan 9, 1919

At the meeting of the Board of Directors the following resolution was passed: "The members of the Board of Directors of the American Institute of Mining Engineers desire: to place on record their appreciation of the very great generosity of one of their colleagues and a member of the Board, George D. Barron, expressed in his gift of $5000 to relieve the financial stringency caused by the unusual expenditures of the Institute for war work and the remission of dues of those members on active service." By-Law VIII. was amended to make a slight change in District No. 5. The report of the Auditing Committee was accepted. Tellers were appointed to: count the ballots on officers and on the proposed amendment. The proposed budget for the year 1919 was presented. The following resolution re Secretary Emeritus Rossiter W. Raymond, which had been prepared, by request, by Dr. A. R. Ledoux was then unanimously adopted. "The Board of Directors of the American Institute of Mining Engineers would place upon its minutes its profound sense of loss and sorrow in the death of Rossiter Worthington Raymond, Ph. D., LL. D., Secretary Emeritus of the Institute. Both as one of its founders and as its Sec-retary for 27 years, his was the guiding spirit of the Institute for more than a generation. "During the greater part of this long period, it might almost have been said that the Institute was Dr. Raymond-and Dr. Raymond the Institute. When with the progress of growth and development, great changes were introduced, Dr. Raymond acquiesced in these in spite of some misgivings, such as those with which a father might contemplate the emergence of his child from the careful supervision of the home; but as Secretary Emeritus for the past eight years, lie was always ready with valuable advice and helpful suggestion.

Jan 3, 1919