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By Giuli M, Barnaba P, Sacerdote R, Tammaro F

Following a theoretical consideration of the effect of flooding, fluidisation and softening on blast furnace blowing limits, results are presented which show the effect of these parameters on operation. Industrial trials on Oscar Sinigaglia No. 4 BF are reported and results compared with those obtained theoretically and in the laboratory. It is shown that in these trials the furnace operated at levels of fluidisation very much (80-90%) below those theoretically calculated whereas in some cases (high proportion of sinter) actual hot metal output was near the calculated flooding limit. However, it was observed that as the sinter percentage decreases also actual productivity becomes lower than the one caused by flooding. This gap, which increases as other ferrous components (essentially acidic) replace the basic sinter was explained by the softening of the burden under bosh conditions. Softening indices measured on the individual materials yield support to this explanation. Coke rates data show that for approximately every one percent increase in the basic sinter in place of blended sized ore, a coke rate decrease of 1.1 kg/thm results. For acidic pellets this value is 0.6 kg/thm. Results of breakdown and reduction characteristics are also given and their indices compared with actual pt oduction. Measures to improve operations are proposed.

Jan 1, 1975

By Myron W. Mellor

Our efforts at McNally, to find a better way to mechanically separate particles from liquid in a slurry have led to the development of two new centrifuges. The first unit utilizes a slotted opening screen as the filter media and retains all plus 200 Mesh and most of the 200 by 300 Mesh particles. The second unit is a solid bowl centrifuge with a novel method of removing the solids and delivers an effluent containing as little as 300 PPM solids in suspension. The first unit was designed to separate particles in the range of about 1 MM x 0 or smaller top size from the liquid slurry and produce solids having low surface moisture content, and a liquid concentrate containing a low percentage of solids. A prototype of this unit has been in the field undergoing tests for over two years. A few of these test results are shown in Tables I & 11. Testing has been mostly limited to the field of coal, how- ever this does not mean that the machine would accept only coal slurries. The machine has produced a dewatered product having as low as 5.5% surface moisture, and an effluent containing as low as 1.4% solids and handled slurries containing from 15 to 50% solids by weight.

Jan 1, 1975

As world demand for various minerals increases the mining industry in its endeavour to satisfy this demand will, eventually,look to the extraction of orebodies which previously may have been uneconomical to mine. These orebodies may be of two types. Firstly, new low grade orebodies and secondly, remnant sections of previously mined orebodies. Some of the factors relative to remnant mining operations are discussed and the potent- ial of remnant mining in providing an important contribution to future world metal production is considered.

Jan 1, 1975

On the 17th November, 1964, a new No., 2 lead blast furnace was blown in at Port Pirie. The furnace departed from previous designs by incorporating a centrally located continuous tapper for both lead bullion and slag. The use of a central tapper permitted a simple and effective layout for the handling of both products. Considerable development was necessary to bring the furnace to its present level of efficiency. Units vital to the continu- ous operation were developed to allow quick replacement, thus ensuring high time efficiency under varied operating and maintenance conditions. The furnace was designed with the following objectives in mind, 1. increased crucible life, 2. elimination of oxygen for slag tapping, 3. higher temperature slag for fuming operations-, 4. less operator skill needed, 5. reduced tapping tool consumption, 6. elimination of settler skull and scrap lead, 7. better control of blast air distributi.nn. And

Jan 1, 1975

By E. h. Erwin Gaertner

Before dealing with the technical equipment of this paper a short survey of the Rhenish Brown Coal Area is given in order to illustrate the special geologic and environmental conditions in this region, which led to the development of the mining technics, used today.

Jan 1, 1975

By Richard A. Sheppard

Zeolites-crystalline hydrated aluminosilicates of the alkalis and alkaline earths-are important rock-forming constituents in sedimentary rocks and are potentially valuable industrial minerals. They have a framework structure that encloses interconnected cavities occupied by the relatively large cations and water molecules. The cations, chiefly sodium, potassium, and calcium, and the water have considerable freedom of movement within the structure and give the zeolite their cation- exchange and reversible-dehydration properties. Some zeolites have essential contents of barium, strontium, or magnesium. The basic structure

Jan 1, 1975

The reasons for selecting two stage pebble milling in preference to conventional methods of grinding are discussed. Commissioning of the first section was completed in October, 1969. Improvements in both the operating and engineering aspects were then incorporated in the section commiss ioned in March, 1971.

Jan 1, 1975

By Richard C. Enochs

In order to clearly understand our process control system it is necessary to briefly discuss the various process control systems that were considered and why we chose our particular configuration. We considered Analog Systems, Computer Supervisory Systems, Computer Setpoint Systems, Direct Digital Systems and Direct Digital with Backup Systems. Our concept of these systems is illustrated in Figure 1 through Figure 5. We chose Direct Digital Control with Manual Backup because it had the greatest flexibility, ease of implementation and cost no more than a pure Analog Control System for one control concept. There would be no increase for a Direct Digital Control with Manual Backup System if the control concept were changed, while there could be considerable additional cost with an Analog System, if the control concept were changed.

Jan 1, 1975

Placing a detonating explosive inside a volume of rock is an efficient method of rock fragmentation. The explosion generates internal tensile stresses in the rock, and because rock is a brittle material, this brings about crack propagation and fragmentation far more efficiently than does application of explosive on the surface. To get the explosive inside, we drill a pattern of boreholes and charge the explosive into the holes. This is really the one and only purpose of making blastholes in mining: to give access for the explosive to the interior of the rock. No matter how big and expensive a drilling jumbo we stand up in front of a rock face, and no matter how many boreholes we let it drill, the rock does not fall apart by itself without blasting. It is the action of the explosive in the boreholes that does it. When we consider that we need a pound or two of explosive for every cubic yard of rock to be fragmented, and a pint of borehole volume for each pound of explosive, we see that the process of blasthole charging is an important element in the whole process of rock blasting.

Jan 1, 1975

By E. A. Lawrence

The experiences of Canex Placer Ltd. in establishing vegetation on a lead-zinc tailing pond are presented, hoping others with similar challenges will be benefited. History The tailing ponds are the result of 23 years of mining and milling operations, which ceased in August 1970. Roughly 7.9 million tons of lead-zinc ore were removed in that time. The ponds are located between Salmo River and B.C. Highway 3, about 8 miles north of Nelway near the Canada-U.S. border.

Jan 1, 1975

By Frank D. McGuirk

Underground coal mining is traditionally hazardous. Although many danger-prone human activities are now performed by mechanized equipment, this mechanization has itself brought new dangers to the underground mining industry, and the loss of life and limb has caused increased concern for mine safety. The 1969 Federal Coal Mine Health and Safety Act has precipitated a great deal of safety-related research on the part of the Government, industry, and private agencies. Much of this safety research has been focused on the new and varied man-machine interfaces caused by increased mechanization. Recent projects in this area have dealt with standardized controls, emergency shutdown capabilities (panic bars, strike plates, self-centering controls, "dead man" controls), and machine operator protective devices (fully enclosed cabs, canopies, side rails). There was a need for integration of the findings of current and past projects to move rapidly toward the smooth, orderly implementation of standardized operator work station designs for underground mining equipment.

Jan 1, 1975

By Moore R

An intensive safety campaign at Mount Isa Mines Limited from 1956 to 1966 saw the lost time accident frequency rate fall to half its original level. A review of the safety programme was carried out in 1967 and in 1968 the Five Point Safety System was introduced. The seven years since its introduction have been years of significant achievement both in production and safety. Improving safety is a fundamental part of Mount Isa Mines Limited's policy and this system has been a major tool in implementing that policy. To be successful personnel need to be prepared and trained for its introduction and subsequently counselled on its use. A carefully prepared programme is required to phase in various aspects of the system and to make use of complementary steps. The system has been a success and it is anticipated that the continued drive to improve the use of principles of the system will further improve safety. It is hoped that this paper will be of value to those personnel concerned with industrial safety in Australia.

Jan 1, 1975

By W. M. Dressel

In producing feed for a lead blast furnace, concentrates analyzing 70 to 80 pct Pb are sintered to produce a physically acceptable low-sulfur product which contains only about 50 pct Pb. Mixtures of PbS with varying amounts of SiO2, CaO, Fe 20., and ZnS were heated in an oxidizing atmosphere at 1,000° C; the products were cooled and examined to determine the problems involved in producing sinter with substantially higher lead levels. Microscopic and electron microprobe studies of the above products as well as experimental and commercial sinters indicate that sinters consist essentially of lead silicates, lead-zinc silicate, calcium zinc silicate, and spinel (ferrite). Lead oxide and lead sulfate areas appear to result from insufficient mixing of the materials prior to sintering. The data give an insight into the process and show that sintering results from a complex interaction of all constituents and that sintering is not simply a matter of diluting the mixture to control the oxidation of lead sulfide.

Jan 1, 1975

By Gary N. Weinrich

Large surface mining projects in sparsely populated regions of the West have the potential to create disruptions in an area's social and economic character with potential effects on man that can far outweigh the physical and ecological effects on man's environment. The data and analyses involved in addressing the socioeconomic issues are additional to those traditionally associated with surface coal mining, such as those concerning land reclamation and water quality. Appropriate socioeconomic studies in conjunction with mine-planning can identify the potential problem areas in order that project measures can be taken to maximize the beneficial impacts and minimize the adverse effects of surface coal mining. The information required to conduct such socioeconomic analyses, available data sources, and the applicable analyses are described. Overall impacts of some proposed Western surface mines are summarized and potential mitigating steps discussed.

Jan 1, 1975

By Samuel S. Adams

Potash, the generic term for a variety of potassium-bearing minerals, ores, and refined products (Table I), owes its importance as an industrial mineral to the potassium requirement of growing plants. The term "potash" originally referred to potassium carbonate produced by the leaching of wood ashes. This process, for which the first U.S. patent was issued in 1790, was the basis for the largest United States chemical industry in the early nineteenth century. The agricultural use of potash soon eclipsed the chemical applications following the German discovery in 1840 that potassium is essential to plant growth. The initial discoveries of large deposits of soluble potassium minerals, essential for agriculture applications, were made in 1857 in Germany and in 1914 in the United States. More than 90% of the 20.4 million short tons K2O produced in the world in 1970 (Eilertsen, 1971 ) was derived from marine evaporite deposits and approximately 90% was used in fertilizers. The potassium content of an ore, mineral, or product is customarily expressed as % K,O, a unit of measure which is neither a natural nor synthetic compound of potassium (1 .O% K is equivalent to 1.2046% K,O) . Geology Potassium, the seventh most abundant element in the earth's crust, is present in silicate minerals in igneous, sedimentary and meta- morphic rocks. Potassium is also a major constituent of many surface and subsurface brines (Table 2). Economic potash deposits are essentially restricted, however, to widespread, thick accumulations of marine chloride evaporite deposits. These deposits yield high grade, large tonnage ore bodies, many of which are amenable to low cost mining and beneficiation. The products from these deposits are, moreover, ideal for use in fertilizer because of the high relative solubility of the potassium chloride and sulfate evaporite minerals. World potash production and reserves for such de- posits so vastly overshadow other sources of potassium that the following discussion will be limited largely to potash deposits in marine evaporites with brief reference to certain potash-rich brines. Approximately 85% of current domestic production is from bedded salt deposits and much of the balance is from brines. Marine evaporite deposits are accumulations of salt minerals deposited in structural sedimentary basins through the evaporation of sea-water or mixtures of seawater and other brines. The salt minerals are precipitated in assemblages and sequences of assemblages as determined by the compositions of the brines and the solubility relations in the salt systems (D'Ans, 1933). The evaporation of seawater normally yields carbonate minerals as the first precipitates (Table 3). Further evaporation and concentration of the brine leads to the precipitation, in succession, of sulfate, chloride, and supersaline mineral assemblages including the salts of potassium and magnesium. The common minerals, ores, and products of potassium deposits are listed in [Table 1]. Many potash deposits contain accessory evaporite minerals together with a variety of detrital and authigenic silicates (Braitsch, 1971).

Jan 1, 1975

By Paul J. Bennett, James E. Castle

The kyanite minerals, including kyanite, silimanite, and andalusite, are anhydrous aluminum silicates with the formula Al2O3SiO2. lumortierite and topaz are also included in this group because they are closely allied in composition and thermal behavior. However, leither are mined commercially today. They ire typical metamorphic minerals which are found in metamorphic rocks on every continent. Kyanite minerals are prized chiefly for their refractoriness and are important components in a broad range of acid refractory products, especially in mortars and castables. World production of kyanite minerals is currently about 250,000 tpy and has been increasing at the rate of 3 to 8% a year for many {ears (Anon, 1972). While kyanite minerals lave widespread occurrence, the consumption of kyanite minerals is concentrated in the relatively few highly industrialized areas where refractories are manufactured, and which in turn are typically close to the major iron and steel producing regions of the world. Thus northern Europe, England, the United States, and Japan are the principal consumers of refractories and kyanite minerals. Of these countries only the U.S. is a significant producer. The largest use for domestic kyanite, both raw and calcined, is in the manufacture of refractory mortars, cements, castables, and plastic ramming mixes. In these applications kyanite constitutes from 10 to 40% of the mixture, the balance being refractory clays and coarser grog materials. A certain proportion of raw kyanite is used to offset the shrinking of the clay binder, whereas the calcined kyanite is used in the coarser sizes for body. Certain high grade refractory shapes and kiln furniture are composed chiefly of graded sizes of calcined kyanite bonded with a little ball clay. In most applications, however, kyanite is used only to fortify the mix or as a minor ingredient. Some manufacturers of mullite brick use domestic calcined kyanite for the fine-grained portion of the brick, but seldom in quantities exceeding 10% by weight. Kyanite is used by ceramic manufacturers of wall tile and sanitary ware to offset shrinkage and cracking after firing. Indian kyanite has traditionally been used to make the coarse grog sizes needed for the manufacture of mullite brick, and for the grog portions of mortar, cement, and castable mixes. It has been largely replaced, however, by synthetic mullite, high fired flint, and diaspore clay or calcined bauxite for other applications. Indian kyanite is available in lump as well as in granules and concentrates, as are sillimanite materials from India and South Africa. Andalusite is available as 8 mesh granules and as fines with chemical analyses not unlike those of domestic kyanites. From time to time and from place to place minor amounts of other aluminum silicate minerals such as dumortier- ite, topaz, and pyrophyllite have been made available at various prices and specifications, but have not been significant factors in the refractory industry. A mixture of kyanite and sillimanite of relatively fine grain-size and of low iron content was at one time offered to the molding sand industry by the Du Pont Co. as a byproduct from their deposits of heavy

Jan 1, 1975

By Robert E. Murray

It's indeed a pleasure for me to speak to you today about the development and operation of large-scale surface coal mining projects in the western United States. It is an exciting story about American business working to solve a critical national problem -- the energy shortage -- through research, new technologies, financial innovation, and imaginative management. The North American Coal Corporation -- the second largest independent mining company and ninth largest United States coal producer -- is proud to be a part of this story. Our operations in North Dakota reflect the coal industry's Western activities. So, today, I would like to focus on our planned involvement in that state. I'll briefly survey why North American is developing large- scale surface mining in North Dakota, and I will outline the many problems associated with this coal development and how we are working to solve them. Finally, I will look at the financial and management techniques we are using to make it all work. In short, I'm going to present a case study of Western coal mining. Let's begin by looking at the reasons we are in North Dakota. The United States Bureau of Mines estimates that 44 per cent of the nation's total recoverable coal deposits underlie the three Northern Great Plains States of North Dakota, Montana, and Wyoming. We estimate that North Dakota alone has about 25 billion economically surface-mineable tons of coal with today's technology. North Dakota has the energy that could keep our factories running and our homes lighted In the years ahead.

Jan 1, 1975

By Stanley J. LeFond, Neal Davis

Drilling an oil well or most other types of drilling or coring is no longer a simple and uncomplicated operation. Drilling today at depths which exceed 30,000 ft is hazardous and requires personnel with long and varied experience in drilling. It also requires extensive experience and knowledge in the use of materials which are added to the drilling fluid or "mud," more often than not materials utilizing an industrial mineral. The drilling fluid can vary from a simple mixture of water and "mud" to a very sophisticated, scientifically compounded drilling fluid. Industrial Minerals Used in Drilling Fluids Industrial minerals which are commonly used in oilwell drilling and completion are listed on [Table 1]. The most important minerals, determined by sales, are bentonite and barite. The other minerals listed are either used to achieve a specific purpose or are used regularly but in limited quantities. The main suppliers of drilling fluids internationally are Magcobar Div., Dresser Industries, Inc.; Baroid Div., National Lead Co.; IMC Drilling Mud Co., (a subsidiary of International Minerals and Chemicals Corp. and Halliburton Co.) ; and Milchem, a division of Baker Industries. Most of the industrial minerals are found in North America, with barite mines and processing plants located in Nevada, Arkansas, Missouri, and Arizona, and bentonite mines near Graybull, Wyo. Other mines, such as those in Nova Scotia, are capable of shipping to South America and to the European and Middle East countries. Most of the materials processed by any of the suppliers must conform to specifications set by the American Petroleum Institute (API) or the Oil Companies Material Organization (OCMA). These specifications provide for uniform physical and chemical properties of the materials to be sold on the open market.

Jan 1, 1975

By J W. Edl, F C. Wu

In instrumented model rock blasting experiments in granite blocks, best fragmentation results were obtained when delays between holes were 1 to 2 milliseconds per ft. of burden and when a rectangular shothole pattern was used with spacings larger than the burden. Effective fragmentation in multiple hole blasts seemed to depend primarily on the full development of the crack network around each hole before the charge in the next hole was detonated. The test results showed that simultaneous or almost simultaneous initiation of shotholes in bench blasting resulted in poor fragmentation.

Jan 1, 1975

By William P. Harris

The Lincoln Terminal System is described as a device with the capability to deliver technical information, monitor student performance, and assure learning in industrial training. An experimental unit, the LTS-3S, was constructed and delivered to the Bureau of Mines with appropriate lesson material for a test of feasibility and acceptability of this form of training in the mining environment. Operations were conducted at two mine maintenance schools. The overall results were that (1) there was a substantial improvement between tests before and after self-training on the LTS, (2) students found this an acceptable way to learn, and (3) reaction by training personnel and supervisors was favorable toward the feasibility and advantages of using the LTS in the mining environment. Transfer of the LTS to industry depends on availability of reliable units and adequate lesson material. The requirements for authors of training materials were established based on advice from mine training experts, formal analysis of lesson development procedures, and experience from efforts in lesson development at Lincoln Laboratory-It was concluded that experienced mine training instructors were best qualified to proceed effectively and economically to format instructional material for the LTS, if supported by well-designed facilities and services. Discussion with mining experts confirmed the desirability of generating training materials and delivering instruction at distributed locations to meet local training needs and in direct support of industrial operations.

Jan 1, 1975