Search Documents

By Charles F. Stack

The A. P. Green Refractories Co. operates clay mines in ten states. Eight of these states have reclamation laws with which we have to comply and indications are that the U. S. Congress will pass a federal surface mining reclamation act in the near future. These regulations, in addition to the value of land in most areas, dictate that mining and reclamation be considered as a single operation. In many instances the land may be more valuable after properly planned mining and reclamation than before. Refractory clay, commonly called "fire clay" is defined as a siliceous clay rich in hydrous aluminum silicates, capable of withstanding high temperatures. It is deficient in iron, calcium, and alkalies and approaches kaolin on composition. Refractory clay is much more limited in occurrence and usage than common clay or shale. During 1971, common clays and shales were mined in 47 states with a total production of 45 million tons. Fire clay production was reported in 22 states with a total production of only slightly over 3 million tons.(1) Many of these producing areas are extremely limited in extent and production. Several are contained within a one or two county area. This reflects the unique geological conditions required for the formation or development of fire clay. The major fire clay producing areas in the United States are shown in Figure 1.

Jan 1, 1974

By C. E. Stack

For the purposes of this presentation, "refractory clay" is intended to include any clay suitable for refractory products and thus represents a description based on industrial application. Other common examples based on use would be white-ware clay, bleaching clay, paper clay, or cement clay. Most users and producers of refractories have specific quality requirements which determine the quality or type of clay that can be utilized. Many clays can however be interchanged or substituted in use by changing manufacturing processes or upgrading less desirable clays. U.S. Bureau of Mines publications (Ampian, 1985) categorize days into six groups. These are kaolin, fire clay, ball clay, bentonite, fuller's earth, and common clay. These are practical groupings based on clay production and usage in the United States. Among these groups bentonite, fuller's earth, and common clay are primarily composed of the minerals, smectite, illite, or chlorite, and are non-refractory. Kaolin, ball clay, and fire clay are commonly used in refractories and thus qualify as refractory clays.

Jan 1, 1986

By W. S. Dyer

Introduction In northern Ontario, refractory clay is found on four rivers of the James Bay watershed: the Abitibi, the Mattagami, the Missinaibi, and the Moose. The clay all belongs to the same geological formation ( the Mattagami of Lower Cretaceous age) , and occurs within a structural depression or 'basin', the boundaries of which have never been defined but which appears to cover at least 1,500 square miles of territory. The recently constructed James Bay extension of the Temiskaming and Northern Ontario railway crosses the northeast end of the basin at the Onakawana lignite field, which by rail is 126 miles north of Cochrane, 605 miles north of Toronto, and 60 miles southwest of Moose Factory. Smoky Falls, the northern terminus of the railway owned by the Spruce Falls Power & Paper Company, Limited, is 7 miles south of one other point in the basin, i.e., the outcrops of refractory clay, sand, and kaolin at the foot of Long rapids on the Mattagami river. Smoky Falls is 50 miles north of Kapuskasing. In a very early report(l) , Dr. Robert Bell, of the Geological Survey of Canada, described '"light coloured marl in horizontal beds" from the Missinaibi river, and noted that the lignite also occurring in the river was probably :associated with the marls. This was undoubtedly the Cretaceous refractory day. Other early writers noted the occurrence of fire-clays, but it was not until Joseph Keele(2), of the Geological Survey, visited thee region in 1919 and studied the clays that their real significance was known.

Jan 1, 1933

By O. N. Sikazwe

The Nchanga Cu-Co ore deposit of the Zambian Copperbelt, is hosted in Neoproterozoic siliciclastic-carbonate sedimentary rocks, and it consists of two orebodies: the Lower Orebody (shale) and the Upper Orebody (arkose). Refractory Cu ores present in the Upper Orebody comprise 150 Mt with average 0.87% Cu, and are characterized by inadequate recovery of copper by leaching. This materials characterization study, conducted on refractory ore samples from the Upper Orebody using optical microscopy, QEMSCAN®, and microprobe, has shown that copper occurs mainly in biotite, phlogopite, malachite, pseudomalachite and goethite. QEMSCAN® has quantified the abundance of each phase and total Cu deportment in each phase.

Jan 1, 2008

By K. Yarnaguchi

In the Mitsubishi Continuous Copper Converting Furnace, calcium femte slag is used. Due to its extremely high basicity, the improvement of corrosion resistance of the refractory lining is in need. In order to clarify the corrosion mechanism and to search for a new corrosion resistant material, first, the surface snuctures of bricks corroded in molten slags were observed by EPMA. Second, the dissolution behaviors of sintered MgO-based pellets containing various oxide additives were examined. It was found that the formation and the dissolution of magnesiofemte at the surface of the bricks play an important role in their corrosion and an addition of NiO, Mn02, or Ti02 to MgO is effective in stabilizing the magnesio-femte and improving the corrosion resistance of MgO.

Jan 1, 1994

By D. R. Kreuzer

The sulfide smelting industry is striving for up-scaling their operations by increasing the throughput and efficiencies of the furnaces. The physical phenomena related to refractory materials prevailing in smelters and furnaces are highly complex. The refractory materials are exposed to fairly high temperatures, thermo-mechanical stresses, penetration of pores, erosion and chemical corrosion. The application of numerical simulation tools is needed for the refractory engineering task to consider those phenomena and to evaluate the impact of operational regimes on the refractory design and finally on the integrity of the furnaces. The work discusses case studies of simulations addressing problems and questions related to the refractory design process. Practical simulation approaches which employ simplified models are introduced as the engineering process demands results in a reasonable time.

By N. R. Shoko, J. Chirasha

Refractory design remains the most fundamental factor in furnace construction. Refractory design details and proven technology consideration is of paramount importance to come up with an optimum furnace life and to maintain productivity in the life span of the furnace lining. The failure to produce a technically or operationally durable refractory design lining could give rise to pre-mature deterioration of the refractory lining and furnace shell. The premature failure of the furnace lining will lead to extensive heat losses, furnace bath shift, change in taphole orientation and alteration of the Pitch Circle Diameter. A combination of these were experienced at Zimbabwe Alloys? new high carbon ferrochrome furnace. The Zimbabwe Alloys experience has shown an excellent furnace performance in the first two years of operation although signs of an anomaly showed within the first six months of the new furnace. Production slowed down due to induced problems from refractory failure causing furnace distortions impacting on the availability of the furnace and smelting capacity. This paper presents the lessons learnt, measures taken to deal with the premature failure and constraints within which the situation was managed.

Jan 1, 2007

By W. F. Rochow, W. C. Burke

Numerous designs of linings and accessories, including dams, lifters, and heat exchangers, contribute greatly to kiln efficiencies. Greater conductivity is achieved with basic brick than with fireclay and high-alumina refractories, depending largely upon the use of steel plates in radial joints between adjacent brick to increase heat transfer through the lining. Refractory lifters expose all portions of the load to radiant or convective heat and raise some portions to higher temperatures by cascading the load down through the path of the hot gases.

Jan 3, 1955

By J. P. Bennett, K. S. Kwong

Slagging gasifiers are used to produce chemicals and/or electricity from feedstocks such as coal and/or petroleum coke. A gasifier environment includes pressures from 400 to 1000 psi, temperatures from 1250-1550°C, are cyclic, reducing gases of CO and 112, and molten ash that interacts with the refractory liner materials. The high Cr2O3 refractory liners of gasifiers fail within 3 to 24 months. Gasifier users seek materials with increased reliability and service life. This paper discusses causes of refractory failure and efforts to increase refractory service life.

Jan 1, 2004

By C. G. Anderson

The treatment of materials for the recovery of the precious metals imposes many processing and environmental challenges. Sunshine Mining and Refining Company has developed hydrometallurgical technology for recovery of values from refractory precious metal materials. At Sunshine, the industrial focus of these processes has been for the direct recovery of silver without cyanidation. However, recent work has indicated that these technologies can provide a means for treating complex, refractory gold concentrates. This will be the focus of this paper. The practice of pretreating ores and concentrates to make them more amenable to cyanidation is becoming more common. Several pretreatment options for sulfide concentrates containing gold include roasting, bio-leaching, direct pressure oxidation and nitrogen species catalyzed pressure oxidation. The industrial use of nitrogen species catalyzed pressure oxidation has been limited to the Sunshine refinery where its focus has been for the treatment of silver concentrates. Much of the reluctance, outside of Sunshine, to use this type of technology may be based on the perception that high costs are associated with using nitrogen species (e.g. nitric acid, sodium nitrite) to leach. Also, the use of nitrogen species catalyzed pressure oxidation on an industrial scale is unfamiliar to most metallurgical professionals. A summary of pressure leaching processes which utilize nitrogen species as a catalyst is presented in Tables 1 and 2.

Jan 1, 1996

By John R. Goode

The fist part of this paper comprises a general discussion on refractory gold ores and their mineralogy. Processing methods now in use are reviewed and test procedures for the important methods are discussed. Factors determining the selection of a process are outlined. The paper includes a survey of production plants using pressure oxidation, roasting and biological oxidation to process refractory ore. The status of processes under development is briefly reviewed.

Jan 1, 1993

By C. J. Hunter

Prior to the commissioning of the Sansu Sulphide Treatment Plant (STP), Ashanti Goldfields' treatment facilities were capable of producing some 700 000 ounces of gold per annum. Ore sources were underground refractory sulphides, surface oxides and old tailings dams. In order to increase the mines production to 1 million ounces per annum and to accommodate the change in ore sources as surface mining moved into fresh sulphides, a part of the strategy adopted was -the construction of a new sulphide treatment plant with a capacity to mill 2.2 million tonnes per annum and produce 400 000 ounces of gold. The STP has been designed, built and commissioned. and has been in operation since February 1994. The Plant boasts the world's largest Bio-oxidation facility which is capable of treating 790 tonnes of sulphide concentrate per day at a grade of 11.4% sulphur and is currently undergoing an expansion to increase its capacity to 1050 tonnes per day. The following sections describe the reasons for selecting the BioX® Process, the plant design, the commissioning experience and the plant performance to date.

Jan 1, 1996

By Andy Cole, Stanley Bunk, Steve Dunn, Thom McCord

In 1994, Goldstrike initiated a research program to investigate processing options for treating what was then the small amount of carbonaceous ore identified in the reserves. The focus of the research was on developing a process which incorporated the autoclave technology already utilized at Goldstrike. Over the next two years, Barrick pursued the development of an ammonium thiosulfate leaching (ATS) process. During the period in which the ATS research was being conducted the amount of carbonaceous ore in Goldstrike's reserves increased substantially and continued growth was projected. By 1996, significant advancement was made on the development of the ATS process. The work culminated in a series of integrated pilot plant runs incorporating autoclaving, ATS leaching, resin in leach, stripping and cementation. Several questions about the process chemistry remained unanswered, preventing commercial development. Barrick was committed to producing gold from the carbonaceous ore reserves by 2000. A due diligence review of carbonaceous ore processing options was initiated during the second half of 1996. Processes considered in addition to ATS were fine grinding/autoclaving, as practiced then by Santa Fe, and whole ore roasting as practiced by Independence Mining and Newmont. The objective by year-end was to recommend the most robust and economical process for Goldstrike's carbonaceous resources. In the fall of 1996, a detailed review of roasting as a processing alternative for Goldstrike was initiated. Throughout the ATS development period, whole ore roasting was used as the benchmark. All the ATS metallurgical and financial results were compared to roasting bench top test results. It was clear this data was too imprecise for use in due diligence study, a more definitive recovery value was needed to complete the carbonaceous ore review. The primary goal of the roasting review was to conduct pilot plant roast tests to gain a more thorough understanding of Goldstrike's carbonaceous ore's response to roasting and its effects on gold recovery. Using the test facility at Hazen Research, four pilot plant campaigns were conducted to determine optimum roast conditions and further define metallurgical design parameters. Conventional two-stage fluid bed technology based on Freeport­McMoRan's roasting patent was the specific process basis for testing. The ore's response to roasting exceeded expectations. In January 1997, a preliminary economic evaluation comparing ATS and roasting was presented, and the outcome was approval to proceed with a roasting prefeasibility study. In July 1997, approval for Goldstrike's Roaster facility was received and basic engineering started immediately thereafter. Detailed engineering _began in January 1998 and plant construction commenced in October 1998,t, Goldstrike's Roaster facility is designed to treat 12,000 tpd of a refractory gold ore, which contains both pyrite and organic carbon. Circuits in the facility include primary and secondary crushing, dry grinding, roasting, gas handling, neutralization, thickening and standard CIL. Gold desorbtion and recovery is carried out at Goldstrike's existing refinery. Plant start-up of the first dry grinding and roasting train is scheduled for March 2000, with the second train coming online in May 2000.

Jan 1, 1999

By J. R. Goode

The first part of this paper comprises a general discussion on refractory gold ores and their mineralogy processing methods now in use are reviewed and test procedures for the important methods are discussed. Factors determining the selection of a process are outlined. The paper includes a survey of production plants using pressure oxidation, roasting and biological oxidation to process refractory ore. The status of processes under development is briefly reviewed.

Jan 1, 1993

By R. C. Dunne

A review of the current ?state of the art? of refractory gold treatment will be provided. This will include a global perspective of refractory processes past and present and the location of currently operating plants. Some discussion on the challenges that face the refractory gold industry will also be provided. Keywords: refractory gold treatment, flotation, roasting, pressure oxidation, bacterial oxidation, preg-robbing gold ores, fine grinding.

Sep 1, 2012

By E. D. Sehnke

The refractory materials industry provides the largest commercial market for nonmetallurgical grade bauxite. Refractory grade bauxite is prepared from bauxites having low iron, titania, and alkali content by calcining at temperatures near 1,650° C. Although there are substantial bauxite reserves in the world, premium grade bauxite ores suitable for use in refractory applications are limited to only a few specific sources, primarily in Guyana and the People's Republic of China. Consumption of bauxite for refractory use is closely associated with the production and consumption of primary metals, in particular iron and steel. Barring major disruptions within the principal producer nations, sufficient supplies of refractory bauxite will be available to meet world demand well into the next century, and raw material costs will continue to determine the availability of markets for bauxite-based refractory products.

Jan 1, 1992

By I. Donohue, M. Pearson, E. Barrette

"This paper presents the technique and benefits of the finite element approach for designing the refractory lining in pressure oxidation autoclaves. One-dimensional equations are used to develop an initial refractory design. ANSYS Parametric Design Language (APDL) scripts are then used to build and analyse a more accurate three-dimensional finite element model to verify the refractory thickness, determine weld overlay requirements, and assess mechanical stability. The APDL scripts provide a cost effective means to quickly evaluate various boundary conditions and multiple designs to determine the optimal lining configuration and nozzle layout.INTRODUCTIONNew ore processing facilities demand increased capacity, requiring hydrometallurgy processes that have larger reactor vessels operating at higher pressure and temperature. Many pressure hydrometallurgy operations require vessels with an impermeable membrane and one or more courses of refractory or ceramic brick. The membrane provides corrosion protection for the vessel shell and the brick provides thermal protection for the membrane. Designing a refractory lining with an economic service life as a thermal barrier requires the refractory to be erosion resistant, chemically compatible with the process fluid, and mechanically stable. A fundamental understanding of the factors affecting the lining system is essential as designs move further away from the industry’s experience base.During basic engineering the refractory lining design is developed using one dimensional cylindrical conduction equations for heat transfer and classical hoop stress-strain relationships for determining mechanical stability. The results of the thermal calculations specify the refractory thickness that should prevent the membrane temperature from exceeding the design limit. Mechanical stability of the lining is determined by examining the sensitivity of lining stability with respect to various parameters. There are three criteria that must be satisfied to conclude mechanical lining stability:"

Jan 1, 2012

By T. Egleston

ALTHOUGH the success of metallurgical operations depends so largely on the possibility of finding proper refractory materials, which enter so prominently into the cost of their operations, it can hardly be said that our knowledge of them is in a very satisfactory condition, or even that we know very much about them, beyond a few facts which have been gathered through their use. Experience, as a general thing, is an excellent master, but the requirements of * This article was written at the suggestion of the Committee of the Institute on Refractory Materials, with a view of calling attention to the anomalies and difficulties of the subject. It was hoped that its discussion would eventually lead to the appointment of a Commission, by the great metallurgical interests of the United States, to investigate the whole subject, since it is believed that a better and cheaper artificial product can be made than any now in use, and that many other important incidental results would be accomplished by such an investigation.

Jan 1, 1876

By Claus G. Goetzel

SOME of the reactions and procedures upon which modern techniques in the production of metal powders are based were used for 2000 years by the ancients to reduce iron and other metals from their ores. Despite this, however, the art of powder metallurgy is relatively new and probably stems from the introduction of incandescent electric lamp filaments. Attempts to improve upon Edison's carbon filaments led to the production, in order. of metallic filaments of osmium. tantalum.. and finally of tungsten, which ha, replaced the others and is the commercial product of today. These metallic filaments were originally manufactured by the extrusion and sintering of a mixture of the metal or its oxide with a reducing agent which also served as a binder. Further progress in this direction was in the pressing of a small percentage of nickel with the tungsten. The sintering operation was carried out in an atmosphere of hydrogen, at a tem-

Jan 1, 1944

By M. A. Boucher

The purpose of my presentation is threefold: a) to make you aware of what is available in Canada in terms of refractory minerals. b) indicate the mineral deposits that have potential for development. c) show the advantages of Canada as a supplier of electrical energy necessary for the production of electrofused minerals. Canada is a producer of natural refractory minerals, electrofused minerals, and synthetic refractory minerals. Several deposits also have good potential for development. The natural refractory minerals produced in Canada are shown in Table 1. The major minerals by decreasing order of importance in terms of tonnage and values are: dolomite, graphite and magnesite.

Jan 1, 1992