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By K. L. Hanning

Grinding and classification circuits at Climax Molybdenum Co. are described. Since the installation of a direct digital control computer in 1974, a number of control strategies were developed and evaluated. This paper deals in particular with the practical experience and results obtained in direct digital control of a wet grinding circuit consisting of a ball mill, constant speed sump pump, and hydrocyclones. For this circuit throughput is maximized, while maintaining a desired product size. Product size is inferred from measurement of operating variables.

Jan 1, 1977

By William E. Robinson

Why did it fail? My first reaction when assigned this topic was to say: because somebody "goofed"--then thank you all for letting me say those few words, then promptly sit down. All of you have been bandying this problem around for many years--so all of a sudden I should come up with the solution. Well, While I might not provide you with your particular answer, I think I can show you some of the resolutions to it. Somewhere along your path of experience you may have discovered that a good formula for starting a fight is to tell a group of dedicated (Nordberg Crusher) users they should be using (Allis-Chalmers), or a group of (Allis-Chalmers) 'users they should be a (Traylor). Now, if you really want a melee, get both groups together and tell them they should be using a (Stedman Cage Mill). This is one sure way you can learn how great minds arrive at logical, well thought-out conclusions, based on all the relevant facts. Why did it fail? I could go on for hours giving you specific reasons why. One of my engineering professors used to start his new class off each year by writing on the blackboard--four and two, then turn to the class and ask: What is the problem? One brave scholar would venture to answer 8. His head would shake no. Another would dare 6. Again, a head shake. Now that the ball had gotten rolling, a number would vocally decide it had to be two, which produced only another shake of the head--no. All of them had missed the question he had asked : What is the problem? What he had gotten ,were some of the possible answers to the problem.

Jan 1, 1977

By Frank Cook

As in other areas of the country, surface coal mine productivity in the Central Coal Province--primarily Illinois, Indiana, and west Kentucky--has declined steadily since 1969 (figure 1). Productivity, as measured in tons of clean coal produced per man-shift, dropped 35 percent during the period 1969-1975. Unwelcome at any time, this phenomenon is particularly untimely now, when increased coal production is a national goal. The U.S. Bureau of Mines has been working with the coal industry to develop new operating methods and equipment to enable increased productivity and improved reclamation performance in surface coal mining. Several projects have involved identification and evaluation of existing overburden handling and reclamation practices, and development of means to improve operational procedures. Some results of one of those projects, as they apply to the Central Coal Province, are summarized in this paper.

Jan 1, 1977

By Harland E. Cofer

A computer-assisted resources and sedimentological study of the Andersonville, Georgia kaolin-bauxite district was begun in 1975 under a grant from the Office of Mineral Resources of the U.S. Geological Survey (Grant # 14-08-1110-G-173). A preliminary report on the kaolin and bauxite resources of the district has been placed on open file at the U.S.G.S. in Reston, Virginia; the Georgia-Geological Survey in Atlanta, Georgia; and Georgia Southwestern College in Americus, Georgia. In addition to a resources estimate, the objectives include the determination of the mineralogical variation, sedimentological parameters, and paleogeographic patterns of the deposition of the high alumina materials and their associated sediments. In the process of compiling data for the resources estimate, isopach maps were developed that provide information as to the shape, size, and distribution of the kaolin deposits and the kaolinitic sediments that contain them. These or similar maps developed for other districts can be useful exploration tools.

Jan 1, 1977

By Thomas L. Kesler

Lithium raw materials usable with present technology consist of pegmatite ore and surficial evaporite brine. Those advantageously located now supply world markets. Materials of similar grades and magnitude, but less favorably located, will come into production as present sources are depleted and markets expand. Some of these potential supplies have been explored, and are reserves in the sense of known availability and quality. Reserves herein are of two classes, those proved by close drilling and assaying, and those of only probable status because their scale and grade are unsystematically indicated. Possible resources include similar materials whose bulk can only be inferred on indirect evidence. All figures apply to total materials in the ground. No allowance is made for losses in mining, evaporation, beneficiation, or chemical processing.

Jan 1, 1977

By Larry D. Patts

Section 317(e) of the Federal Coal Mine Health & Safety Act of 1969 directed the Secretary of the Interior to prepare standards under which all working places in a mine shall be illuminated by permissible' lighting while persons are working in such places. Section 317(e) further provides that such Working places shall be illuminated within 18 months after such standards are promulgated. In accordance with this section of the Act, there was published in the Federal Register for December 31,1970 a notice of proposed ru1emaking which prescribed the illumination to be provided in the working p1 aces of underground coal mines. In 1ight of written comments, suggestions, and objections to this proposed ru1emaking, the proposed standards were with-drawn and reproposed in the Federal Register for Wednesday, October 27, 1971. In light of further comments, suggestions, and objections, a public hearing was held on April 4, 1974 and standards were again reproposed and published in the Federal Register for April 1, 1976. Promulgation of the final lighting standards took place on October 1, 1976 which means that the underground coal mining industry must comply with face illumination requirements by April 1, 1978. As mentioned previously, the first proposed ru1emaking for illumination of underground coal mines was published in the Federal Register on October 27, 1971. In early 1972, Consolidation Coal Company (Consol) and the United States Bureau of Mines agreed to a cooperative study of underground face illumination; Conso1 felt that expertise in this field would become increasingly important. Conso1's initial efforts in illumination were aimed at investigati.ng practical lighting systems for underground face equipment. We were concerned with installing unobtrusive lights which provided sufficient face illumination for safety, but at the same time were readily maintainable, electrically reliable, and physically sheltered from damage.

Jan 1, 1977

By David A. Summers

In May 1975 the U. S. Bureau of Mines contracted with the University of Missouri-Rolla, Rock Mechanics and Explosives Research Center to develop a Hydrominer modification to a long-wall shearer unit, wherein the rotating pick-laced drums and connecting gear drives are replaced by a water jet cutting head.1 The concept of the water jet cutting head is based on using the high localized energy of the water jets to isolate a slice of coal by cutting a slot under, at the back of, and at the top of the web. The plow blade of the head then advances into the cut and wedges the pillar over onto the conveyor (Figure 1). There were several potential advantages foreseen for the system of which perhaps the most significant were the elimination of coal dust from the working area2 and the ability, with a variation in nozzle geometry, to cut webs of greater depth with a small increase in equipment horsepower. The University initially designed the head, based on experiments carried out in the laboratory, under an earlier Bureau of mines contract. The experiments showed that it was more advantageous to work at a pressure of 10,000 psi with an estimated flow rate of 50 gpm than go to the higher pressures and lower flow rates which have been advocated elsewhere.

Jan 1, 1977

By Richard Klimpel

1. Introduction Laboratory and industrial grinding tests have shown that the process of size reduction can be significantly influenced by chemicals added to the powder or slurry being ground. The terms grinding aid or grinding additive refers to a substance which when mixed into the mill contents causes an increase in the rate of size reduction. The increased rate can be used to grind a higher feed rate to the desired product size or it can be used to produce a finer product size at a fixed feed rate. Whether the use of a grinding aid is justified in any given situation depends on the cost of the substance versus the improvement of output or product quality obtained with its use. Obviously, an expensive chemical must be effective in very small concentrations if it is to be economically justifiable; the cost criteria is calculated on the basis of the cost of the grinding additive per ton of material ground. Although there is direct experimental verification of the advantageous effect of grinding additives, no sound scientific explanation has yet been offered which explains or predicts the general behavior of additives. Rose and Sullivan have summarized most of the work undertaken prior to 1950 and Hartley, Prisbrey, and Wick have recently prepared an updated synopsis of the grinding additive literature. Many of the studies reported consist of subjecting materials with simple geometric shapes to some type of hardness or controlled single fracture test. On the other hand, a number of the studies were carried out on operating industrial scale mills, with little control or precise monitoring of the effect of the additives.

Jan 1, 1977

By Z. M. Zavodni, M. K. McCarter

This paper identifies physical conditions responsible for past instability of the Main Hill area in Kennecott Copper Corporation's Bingham Canyon Mine, Bingham Canyon, Utah, and describes successful stabilization techniques employed in this slide zone. Geotechnical highlights of recent slides are presented, including monitoring, geological engineering data collection, hydrology, physical rock properties, and stability analyses. Local conditions responsible for slope movement in the Main Hill zone are: (1) high pore water pressure that causes a substantial decrease in real and effective material strengths; (2) continuous structural systems that allow sliding in the more competent rock zones; and (3) broad areas containing fractured, altered , and incompetent rock and soil- like materials. The failure mode is structurally controlled and involves a circular-type soil failure in the toe region initiated by excessive pore water pressure. A surface mapping method is presented which assigns rock mass quality on the basis of block size and rock substance strength. This site characterization technique has successfully predicted slide boundaries and failure modes; used in conjunction with laboratory determined shear strengths, it has provided basic input for calculating slope safety factors in the Main Hill slide zone.

Jan 1, 1977

By L. P. Johnson

Longwall mining has gained acceptance as a safe method of maintaining coal production where conventional systems were unsuccessful or uneconomic due to bad roof conditions (Kuti8). One of the major problems confronting American operators involves the correct choice of equipment which should be selected to suit the local mining and geologic conditions for optimum productivity. To achieve this, factors such as rock strengths, local geology, panel geometry, and panel orientation must be examined to optimize production and minimize down time due to ground control problems. Little quantitative information is available in the literature regarding the effects of geologic conditions on American longwall operations, and past implementations of longwall systems appear to have been based largely on experience. When mining engineers are able to assess the geologic conditions both quantitatively and qualitatively, they can more fully optimize equipment selection and panel design.

Jan 1, 1977

By Kenneth R. Krivanek

In recent years the widespread problems of air and water pollution generated by both population and industrial expansion have become a major public concern. Therefore, many municipalities are striving to achieve more efficient wastewater treatment processes so these wastewater's can be reintroduced into the waterways of our nation with little or no detrimental effects on the future beneficial use of that water. With this, improved treatment comes an ever increasing volume of wastewater sludge which must be disposed of in a manner of minimal impact on the environment. Furthermore, with demand for energy continually accelerating in this nation, our concern over high oil prices and our increasing dependency on foreign oil sources, there has been an ever growing interest in the largest energy source that are nation has, coal. However, surface mining of coal can cause many environmental problems when adequate precautions are not faithfully adhered to. These problems include water pollution from silt and/or clay erosion and acid runoff, produced by oxidation and hydrolysis of pyrite; i.e., FeS2 + 3/02 + H20 + FeSO4 + H2SO4. One method of wastewater sludge disposal which can utilize large volumes of sludge for a beneficial project that may not compound our environmental problems is spray irrigation, to either depleted farmland or to abandoned strip-mined soils. Sludge is characteristically high in organics, as well as having near neutral to alkaline pH properties. With these two qualities it possesses a potential for neutralizing acid strip mine spoils, which would enhance the establishment of a vegetative ground cover. Sludge can accomplish this by lowering the oxidation potential, reducing the solubility of iron and aluminum and by the chelation of metals, thereby

Jan 1, 1977

By Nick Hasenack

In the pelletizing plant of Hoogovens, Estel BV, a varying mixture of hematites and magnetites is used for the production of acid and (occasionally) fluxed pellets. Optimum results regarding productivity, quality and process control are obtained with mixtures containing 30-40 % magnetites. A decrease of the magnetite ratio or an increase of the basicity has a great influence on both productivity and heat and power consumption. Tests have been carried out to find the extent to which magnetite can be replaced by b.f. dust, mill-scale and coke breeze. Pilot plant tests show that about 80-100 % of the production loss due to a decrease in magnetite content or to the increase in basicity can be regained without damage to the quality by adding coke breeze. The amount of coke breeze should be limited tot 1,5 %; if this percen¬tage is chosen higher, the quality of the pellets deteriorates rapidly. The amount of coke breeze to be added should be about 30 % above the theoretical value, based on heat balance considerations. The results achieved by incorporating b.f. dust and mill-scale into the pelletmix were also encouraging, but as some types of mill-scale are very difficult to grind and the supply of b.f. dust is limited, the research has not been carried out extensively in this field. The pilot plant tests on replacement of magnetite by coke breeze have been followed by industrial tests, during which the breeze was added to the ore feed before the dry-grinding system.

Jan 1, 1977

By J. R. Cooper

Since man began beneficiating ores, a limited number of factors influenced the type of treatment. The ore itself has always been a factor. The first form of concentration was probably hand sorting, and the grade of concentrate and recovery had to be considered from the start. The cost of labor as a factor in mill design did not attain importance until the period following World War I. Power was one of the cheapest commodities available, and consequently power consumption was ignored. That no longer holds true. The present work does nothing to simplify the work of the metallurgist, or designer. On the contrary it adds another element to the design considerations. And while this report concentrates on power consumption, the mill designer must take the other factors into account as well. This study is based on a compilation of data supplied by a number of Western United States copper operations, as well as information from equipment manufacturers. Although its conclusiones apply to other minerals and geographic areas, the information is more precise, when applied to similar ores. The discussion has been divided into sections covering crushing, grinding, and flotation as these are the principal power consuming functions.

Jan 1, 1977

By G Luxbacher

Computer simulation of mine ventilation systems is rapidly becoming an essential tool in mine planning and design. This paper examines the utilization of ventilation simulation techniques to evaluate the number, shape, size and layout of mine entries in a typical coal mining system. Since the mains and sub-mains serve mainly for transportation and ventilation and the ventilation system is critically important to the health and safety of the workers, there exists a great need for optimal designs in this area. Evaluation criteria, could include, among others, minimization of power costs, shaft requirements and leakage. Constraints of this optimization problem include health and safety regulations and production and mine infrastructure requirements.

Jan 1, 1977

By Douglas J. Kramm

This paper discusses the history and development of the Rotary Kiln in improved fuel economy. It discusses latest technology to optimize fuel economy in a long Rotary Kiln. It discusses the limestone preheater, the SF process for cement manufacture, and the flash calciner with suspension preheat and. suspension deheat for fine limestone.

Jan 1, 1977

By W. Blake, J. Mahaut, W. Hustrulid

Division II at Kamoto mine in Kolwezi, Zaire represents a transition zone between Divisions I and III where transverse and longitudinal cut-and-fill rooms were being mined. Because this transition zone had been geologically depicted as being badly faulted the mining in this division had been deferred to a future time. However, to increase production and to reduce mining costs by carrying out the mining of the 3 divisions simultaneously, it was decided to mine Division II. The mining research group of Gecamines was given the task of designing a mining geometry then testing this design in a full scale test. Based on an evaluation of the faulting and fracturing of the 2 parallel orebodies and on an extensive in situ testing program preliminary mathematical analyses were used to develop and evaluate room and pillar designs in the 35°-65° dipping bedded formations. Based on these analyses and the constraints of having to fit the design of Division II to grade into Divisions I and III in a logical manner, a mining geometry for Division II evolved. To test this design an instrumented room was excavated in the most critical area. The results of this full scale testing showed that the behavior of the roof and wall rocks were as had been predicted by finite element computer model studies which incorporated the material properties and results of the field testing. The room geometry design was both judged and observed to be stable, hence mining commenced.

Jan 1, 1977

By Jerome A. Westphal

The Middle Mississippi River extends from the mouth of the Ohio River to the mouth of the Missouri River, a distance of about 310 kilometers (km) measured along the river. From its founding in 1764 to the first steamboat arrival in 1817, the City of St. Louis was little more than a trading post. However, with the advent of the shallow-draft steamboat, the Middle Mississippi River rapidly became a major thoroughfare of commerce. In this regard, its importance has been reflected by the development of port facilities at St. Louis and by Federal activity relating to channel maintenance and improvement. First Federal work on the Middle Mississippi River was autho¬rized by Congress in 1824. This work was for snag removal and bank clearing and was directed at reducing the hazards to steamboat traffic, particularly during low-flow periods. During the 1820's and early 1830's, the main channel threatened to move toward the Illinois shore and abandon the St. Louis port facilities. In 1836 and 1837, Congress authorized construction of permanent improvements to keep-the river next to St. Louis (Missouri shore). By 1880, it was recognized that bank clearing activities had resulted in a wider and shallower river which exacerbated navigation

Jan 1, 1977

By James P. Odendahl

Missouri is a state rich in mineral commodities. There is a variety of types of mining as well as minerals in the state. Different phases of mining are controlled by a variety of state and federal laws. What I hope to do today is to present briefly some of the interaction and interplay that has occurred in the recent years between the mineral industry and the Missouri regulatory agencies, as well as some of the interactions by federal agencies. First a little history which dates back to the late 1600's. For many years Missouri has been a leader in the production of lead and zinc. In fact, recent studies have indicated that Missouri produces better than three-fourths of the nation's present lead supply. Less well known but important resource is iron mining. Some of these operations were the source of confrontation during the Civil War. Major battles were fought in and around Ironton, Missouri where iron mining has occurred for many years. One of the largest pelletizing operations in the state is currently located within the city of Ironton. Joplin, Missouri, the home of Thomas Hart Benton, the famous Missouri painter, has a history of lead and zinc mining, going back to the later 1800's. Many of the paintings by Benton contain reference to the early days of mining in Missouri. There is a Benton mural in the City Hall at Carthage depicting the early days of lead mining in that area. Later, the center of lead mining moved to southeast Missouri near Bonne Terre and Flat River. The names of the towns in this area reflect the history of mining, examples - Leadington, Old Mines, Rivermines, etc. The history of lead mining in Missouri has been referred to in some detail in various publications(l).

Jan 1, 1977

By W. C. Morgan

Recently passed federal strip mining legislation officially emphasizes that the increased coal production required by this country through surface mining is going to be obtained only with stricter environmental standards. Dozing overburden down the hillside in Appalachian contour mining or leaving drag1ine spoils in area mining is now taboo and it is now or will soon be necessary to return the disturbed land to as good or better condition than before mining. These new restrictions will create a need for new and better ways to do the job. This paper describes one approach for utilizing scrapers and dozers to strip all of the overburden and to replace that overburden in an environmentally satisfactory fashion. The objective was to do this at a lower cost than that possible with the traditional dragline system using dozers and scrapers for reclamation and topsoil handling. In area stripping, the dragline has been able to move overburden at an extremely low cost. Operating costs of 8-13¢/bcy are typical in many operations where rehandling is not required. However, the cost of leveling the spoil piles and rehandling topsoil add considerably to the low basic cost of drag1ine stripping.

Jan 1, 1977

By Robert C. Freas

Dravo Lime Company has opened a new 290m (940 ft.) deep lime-stone mine near Maysville, Kentucky. As the mine was opened there were many unknowns as to the stress relationships within the rock, and their influence, if any, on the selected mining method. Therefore, a system of overlay geologic and structural maps, borehold extenso-meter measurements, and oriented photography was developed for the purposes of monitoring the internal structural relationships of the rock mass. This paper presents a description of the methods used, the observations made, and the conclusions and recommendations made as a result of the initial monitoring program.

Jan 1, 1977