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By R. J. Sweigard

One of the foremost problems in reclaiming prime farmland is compaction of the subsoil which is caused by the reclamation equipment. Wheel tractor-scrapers are most commonly used to replace subsoil and have been blamed for the majority of the compaction problems. Two methods of alleviating this problem that are presently being considered are mechanical subsoil loosening machines and truck- shovel combinations for subsoil handling. A field study was conducted in which dry bulk density measurements were taken in an effort to determine the effectiveness of truck-shovel combinations and subsoil loosening equipment in reducing bulk density in comparison to typical scraper replacement.

Jan 1, 1987

By S. W. Thomas

One of the most difficult tasks associated with placer mining is the sampling of the deposit. More placer projects have failed due to inaccurate assessment of the reserves than to any other reason. Within the realm of placers, those containing valuable minerals with a high unit value .are more difficult to sample than those with larger bulk, lower unit value minerals. Some items to consider when sampling a placer deposit are as follows: A) A relatively large size sample is needed for accurate valuation of the ground being tested. Placers are composed of many sizes of gravel which makes a representative sample difficult to obtain. B) When sampling placers for high unit value minerals such as gold, any error in mineral content of the sample will be magnified in the calculation of reserves.

Jan 1, 1985

By John Lovering

The Afton property is located 180 air miles East-Northeast of Vancouver and nine miles West of Kamloops, a city of 60,000 people, in South Central British Columbia, Canada. The mine is adjacent to the Trans-Canada Highway at an elevation of 2,200 feet above sea level. The orebody is a porphyry, copper deposit that has undergone supergene alteration. The-major economic minerals in the supergene zone are native copper and chalcocite with chalcopyrite and bornite in the hypergene areas. The grade is one percent with an overall copper distribution: 70% native, 25% chalcocite and 5% chalcopyrite with bornite and covellite. The ore also contains important, but variable amounts of gold and silver.

Jan 1, 1985

By Carl E. Williams

Several years ago it was decided that ASARCO was in need of a good mine scheduling program to complete the computerized open pit mine planning package that was being used on new prospects and operating properties. A trial and error approach was being used to schedule a mine on a year by year basis, but this was time-consuming and far from offering an optimum solution l. Due to the magnitude of time and expertise required to develop such a sophisticated computer program, it was decided to search outside of the company for one already developed and available for purchase, This proved fruitless and therefore proposals were requested from consulting firms that had the expertise to develop such a program. Out of the five firms that submitted proposals, the one chosen was Systems Control, Inc., (S.C.I.) of Palo Alto, California. S.C.I. was selected because it was felt that they offered the greatest capability in the mathematical solution of complex problems. But due to their lack of mining expertise, a cooperative venture was developed whereby ASARCO would supply this mining knowledge. The selection of this vendor, the formulation of the contract and specifications, and the development of the computer program required about 3 years to accomplish.

Jan 1, 1973

By Lynn B. Hales

Everywhere you turn today there are articles on artificial intelligence and the rapid emergence of expert systems. Expert systems form a class of software that has developed as a result of the large research effort to develop computers and software that think intelligently. By definition, an expert system is a computer program that contains the knowledge component of an expert skill, can offer intelligent advice and justify its line of reasoning. Expert systems can advise people on what actions to take and when, assist in the diagnosis of the physical condition of a human patient or piece of equipment, or even take actions without human guidance, as in process control applications. Expert systems can also explain the line of reasoning behind a particular piece of advice or query for information from the user. Expert systems can be used as advisors to newcomers in any field in which mastery is attained by many years of experience. They often can provide expertise more uniformly and rapidly than human experts. Expert systems can also provide a means of documenting expert knowledge and procedures and provide a common repository for a changing knowledge base. The expert system can represent the best expertise available, thought out in the absence of pressure situations. Each of these attributes or characteristics should be helpful in improving typical concentrator control systems.

Jan 1, 1987

By Syd S. Peng

The key design parameters of roof bolting using expansion - shell type support for underground coal mine roof support are bolt length, bolt spacing, installed load and anchorage capacity. Depending on the utilization of suspension effect or friction effect, the bolt length is dictated either by the distance between the roof surface and the first overlying strong strata encountered or the desired magnitude of reduction in bending stress at the roof surface, The current prevailing practices about the bolt spacing and installed load are that an initial torque of 125 - 170 ft-lbs is applied and the bolts are spaced at 4- or 5- ft. square grid pattern. This seems to be a rather broad generalization in view of the great geological variances which are expected in underground coal mines. A modest evaluation program to measure the effectiveness of current roof bolting practices is to monitor the load history of roof bolts during a complete mining cycle including the phases of room development and pillar robbing. The load history, when compared with the anchorage capacity of roof bolts determined by in-situ pull tests, will provide information for evaluating the installed load, the bolt spacing as well as the specifications for structural and anchorage characteristics of the bolt assemblies. This paper presents a case history of monitoring the complete load histories of roof bolts in an underground coal mine of Pittsburgh seam.

Jan 1, 1976

By A. T. Yu

As a nation, we have been known as perhaps the most wasteful in history. From the perspective of engineers and builders on the other hand, planned obsolescence and demolition did beneficially pave way for growth and provided environment for new businesses. Recent economic recession and intense competition from overseas, however, have drastically changed the economics. The high cost of capital and the demise of indiscriminate plant expansion have totally altered the way we conduct our business and run our operations. As a response to increasing demands for better efficiency with little or no funding available, everyone is forced to make do and do better with whatever little he has. Today it nay not be an exaggeration to state that modification of existing facilities may have finally emerged as a way of life. This paper will outline examples of how several companies have effectively modified existing facilities to do more and do it efficiently without having to demolish everything and/or to spend a fortune.

Jan 1, 1985

By Adrian C. Dorenfeld

The concentrator of Bonneville Ltd.* at Wendover, Utah, processes a feed obtained by, solar evaporation of a brine containing sodium and potassium chlorides with minor amounts of impurities. Salable potassium chloride concentrateis produced from this feed in two steps: flotation with amine reagents to concentrate the potassium chloride, and washing of the concentrate with fresh water to reach final grade. In the flotation step emphasis is placed on recovery, whereas the washing step has as its objective the production of salable grade (in excess of 60 percent K20 equivalent), with recovery being important but secondary Ideally, flotation should give maximum recovery at a concentrate grade which will permit washing to salable grade with a minimum recovery loss, thereby maximizing over-all recovery. Except for this relationship, flotation and washing are two separate and distinct operations.

Jan 1, 1965

By George E. Williamson, Mikiya Higuchi, Michael T. Traylor

Extensive soil conditioning was required to allow Earth Pressure Balance(EPB) tunneling on the South Bay Ocean Outfall tunnel project in San Diego, California, near the Mexican border. This tunnel extends 19,000 feet out under the Pacific Ocean and was mined through soil formations including silts, sands, gravels, cobbles, and boulders. EPB pressures ranged from 3.0 to 7.0 bar, with the maximum pressures required when mining through the highly permeable granular formations.

Jan 1, 1999

By Charles M. Brinckerhoff

Everyone -- especially the engineer -- is aware of the great technological and social changes taking place in our world today, We realize that changes have been taking place since man's beginnings on earth, but the element we now face is the speed of change, rather than change itself. Developments in medicine, in transportation, in space exploration, in global communications, and in many other fields, are constantly being made known. These developments are affecting the lives of each of us, although some may appear remote and unrelated to us as individuals. New developments, almost on a daily basis, affect our work as well as our social, religious and educational lives. The effects are immediate and permanent.

Jan 1, 1967

By L. D. Hartzog

A pilot plant investigation of a semi-autogenous mill - ball mill circuit is described. The plant was operated with minus eight-inch diabase as feed material to the semi-autogenous mill. The semi-autogenous mill recycle screen underflow was put to a ball mill in closed circuit with a cyclone. An operating Work Index of 13.3 to 14.9 was obtained with the pilot ball mill. This Index is substantially in agreement with the scalped feed laboratory Work Index for 15.3 for recycle screen underflow. The Bond Index of the diabase was 15.8. Thus, one may use the scalped feed laboratory Work Index to size semi-autogenous grinding plant ball mills.

Jan 1, 1974

By C. L. Lin

Linear grade distribution measurements determined from polished sections of randomly oriented particles can be used to estimate the extent of liberation for multiphase particles of specified size. Two techniques, optical image analysis and microprobe analysis, have been used to establish linear grade distributions. Both techniques were evaluated and compared using variable grade samples of products from a copper porphyry flotation circuit. The statistical significance of the linear grade distribution data obtained by optical image analysis was assessed. The average chalcopyrite content of these samples, as determined by chemical assay was used to estimate the variance of the experimental procedure. For a given accuracy, the number of particles required to obtain an unbiased representation of the sample was determined.

Jan 1, 1985

By Karl S. Vorres

Coal my not seem like it, but it is a perishable commodity. The basic coal scientist cannot always replicate earlier experiments with a given sample because of changes that have taken place in the sample. This has led to a stated need for stable samples Coal looks like a uniform black solid to many people, but it does vary in its composition from state to state and mine to mine it also can be shown to vary significantly within a mine or seam. These variations have led to a stated need for consistent samples.

Jan 1, 1985

By Jay Parrish

Appalachian kimberlites appear to be spatially distributed along two structure parallel trends running from Tennessee to New York. It is hypothesized that the kimberlites were emplaced at the intersection of structure parallel basement faults and cross- structural lineaments. The latter are expressed in potential field and remotely sensed data. The western trend follows the Rome Trough from eastern Kentucky to south central New York. The eastern trend parallels the edge of the Ridge and Valley in Virginia and Maryland.

Jan 1, 1984

By H. G. Fleshman

Thousands of years ago, Chinese water well drillers developed a technique for punching holes in the ground by lifting massive metal bits and letting them fall against the rock. With diligence, they could pound away about 2 feet a day. The Chinese drillers pounded holes in the ground this way for almost 2000 years. In the 1860's, French water well drillers developed a perforated bit moistened by fluids pumped into the hole through a hollow rod. The fluids carried the cuttings from the hole and spared the Frenchmen the task of bailing them out by hand.

Jan 1, 1986

By Dwight K. Smith

Fly ash as an additive for oil well cement was introduced to the oil industry by the Halliburton Company in 1949. Since its early usage in the Illinois area of the U. S., the total amount of fly ash pumped into wells has exceeded 30 million sacks, The advantages of using fly ash-portland cement mixtures in wells are fundamentally the same as for concrete except the conditions of placement and curing are variable and the nomenclature of properties are expressed somewhat differently. In some instances deep wells have been cemented with mixtures of fly ash and hydrated lime together with an activator which functions as a catalyst for setting. This fly ash-lime formula has many advantages for high temperature-pressure conditions found in wells.

Jan 1, 1968

By M. G. Ayat

Although other methods of mineral concentration have been developed over the years, gravity separation remains one of the most efficient and economical for cleaning coal. The concentrating table and the spiral separator are popular devices used for the separation of minerals by exploiting the differences in specific gravities of the product material and the gangue. While the former device has been servicing the coal industry for over 75 years, the latter seems to have not been employed extensively for coal cleaning purposes in this country. As far as coal preparation is concerned, both separatory devices seem to be most efficient for intermediate to fine size fractions. As it stands there exists a great deal of confusion amongst preparation engineers and plant managers as to whether spirals can have a place in the coal industry. If so, whether their come back is the beginning of the end for concentrating tables, or can they be employed along with concentrating tables to contribute toward more efficient cleaning processes resulting in an improvement in the overall economics of the coal preparation industry. This paper examines the efficiency of both systems for coal processing operations as well as the basic principles, operational variables, economics, advantages and disadvantages associated with each unit operation. Attempts have been made to draw conclusions and make recommendations as to which system would be more beneficial for coals of known characteristics.

Jan 1, 1986

By James M. Baylor

Ladies and geltlemen, it is indeed a privilege and a pleasure to be here in Denver with you. I want you to know too I'm not a stranger out here. Golden, Colorado is the headquarters of A. T. Massey Coal Company's Western Division, headed by Vice President, Gregory H. Hoyl. I also have a very close friend and fraternity brother who works and lives in Denver so I could talk on and on about this area and our western coal properties, but it's Massey's coal terminal business I'm to focus in on today, and that's a horse of a different color. So on to the subject of my address: MASSEY COAL TERMINAL INVOLVEMENT As I have stated on other occasions, A. T. Massey Coal Company, for better or for worse, is in the coal terminal business.

Jan 1, 1981

By Yoshiak Mizuta, Hi Keu Lee

The manuscript of this paper was not available for publication when the Proceedings went to press. Should the authors elect, they may distribute copies at the time of the Symposium

Jan 1, 1986

By Z. Yu

Dewatering of a -0.5 mm fine coal has been studied extensively. Deep cleaning requires however fine grinding, and dewatering of such ultrafine products presents a great challenge. Several coal samples finely ground and characterized by different wettabilities have b.een used in the filtration tests. Vacuum and press filters have been employed. In this paper only the results obtained with different flocculants (totally hydrophobic. semi-hydrophobic and hydrophilic polymers) are included. The results reveal the effect of coal surface properties and flocculant type on filtration of ultrafine coal.

Jan 1, 1994