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By S. D. Michaelson

Open pits and quarries are the major sources of all "hard rock" tonnage mined today. Normally, ore is fractured from the pit face by blasting and then truck-hauled to a primary crusher where processing begins; over- burden (or waste) is generally truck-hauled from the pit to dump areas. Truck haulage of blasted ore and overburden accounts for some 25 to 50 percent of total mining costs in a typical open pit and commonly is the largest single cost factor. Obviously then, cost reduction efforts should properly focus on improving existing haulage systems and developing new breakthrough techniques for material transport. Continuous flow systems for large tonnages ordinarily will result in a lower cost than batch systems such as truck or rail haulage. Continuous flow with pipelines for liquids and slurries, or conveyors for medium to coarse dry materials (in the -8 in. range) are the accepted economic answers for bulk materials handling over reasonable distances.

Jan 1, 1968

By K. Rajamani

The word adapt means "to change so that one's behavior will conform to new or changed circumstances." Applying this definition to process controllers suggests that an adaptive controller can change its behavior in response to changes in the dynamics and disturbances of the process. In the minerals industry there are many control cases where adaptive control will provide superior control as compared with more traditional PID (proportional, integral, derivative) control. A typical plant uses as many as 100 to 200 control loops for lprocess regulation. Therefore, the task of initially tuning and then periodically retuning these controllers is a formidable problem, During the time the controllers are "un-tuned", product quality may deteriorate and unstable operations may result. Adaptive controllers are capable of tuning themselves, thus avoiding this problem. The computers commonly used in distributed control systems are easily capable of implementing adaptive controllers. In addition to the possibility of using the control computer to implement adaptive controllers, many distributed control systems will offer adaptive control as a standard feature in the near future.

Jan 1, 1984

Solvent extraction-electro- winning appears to be one of the most important processes for the future in the North American copper industry and for this reason both the SX and EW steps are furtive areas for development. This paper has the objective of reviewing the present state of the electrowinning technology. It discusses some recent equipment developments and concludes by discussing the direction the technology will likely go fn the next decade.

Jan 1, 1985

By G. I. Mathieu

Research and development studies were carried out at the Canada Centre for Mineral and Energy Technology to produce a synthetic forsterite sand from asbestos tailings for Les Sables Olimag Inc. The National Research Council of Canada also supported and collaborated to the project. Theoretically, the technological approach consists of a heat at over 1300°C; however, the process without additive would result in the production of an enstatite-rich product (MgSiO3) having a fusion temperature less than 1600°C. The purpose was to foster the formation of forsterite (Mg2SiO4), a more refractory compound. The fabrication of the forsterite product requires pre-agglomeration of serpentine-MgO with a binder, which is stable at high temperature, to prevent the loss of the powdered magnesium oxide as dust in the kiln off gases and to maintain the mixture homogeneous during the process. Characterization of the end products with respect to mineral composition and thermal resistance are described. The synthetic forsterite in sand form was tested with success under a bath of liquid steel maintained at 1700°C for up to two hours. The advantages of the new sand and its potential applications will be reviewed.

Jan 1, 1992

By Donald M. Hausen

Microscopic evaluation of trace quantities of metalliferous phases in flotation products requires counting large numbers of particles. Particle counts of many thousands may be required for precision, but not obtained practically by conventional microscopic techniques. A less tedious microscopic method for evaluating trace sulfides in mill tailings was developed for the O'okiep Mining Company in South Africa. Hundreds of thousands of particles were evaluated by this method called "gross-counting." Gross-counting consists of counting microscopic fields rather than point-counting individual particles. Total counts are calculated by multiplying the average number of particles per field by the total number of fields examined over the entire mount. Total gross-counts range from about 20,000 particles for +200 to 100,000 or more for -400 mesh size material in lucite mounts. Sulfides and metallic particles in each field are identified and tallied along with field counts. Totals for each type of metallic particle are divided by the total gross-count to give volume percent which is corrected to weight percent by specific gravity factors.

Jan 1, 1969

By Gerhardt A. Bennewitz

The mechanism shown here (Fig. 1) may not be all that it appears to be. To many of you it may look like a hopper car, a thing of mobility, in which you would ship coal, ores, limestone, or other bulk materials. It is approximately 50 feet long, 12 feet high, and can be placed on tracks which are on approximate 14 foot centers. But far too often in the past, and all too often today, this mechanism has been made to serve as an immobile storage box, with its primary role -- the transportation of products, seemingly incidental to the storage function. Our engineering training teaches us to conserve resources, despite some of the popular and misconceived philosophies being advanced these days. Those of you who work for companies with traffic departments know that they are always striving to reduce the price which is paid to move your mine products. Today, let's consider and analyze the ways in which the cost of transporting your mine products might be reduced, based on particular reference to coal. Bear in mind that in this context, cost and price are not necessarily synonymous. Until a few years ago, most coal and other bulk materials handled by railroads moved under standard tariff rules. These rules, which still exist today, provided transportation vehicles (railroad cars) for extended periods at no added price to the shipper or receiver. "Normal" free time rules would permit a car to be held for a maximum of 48 hours without charge; however, in the case of coal, there is a rule which, subject to liberal rules as to the

Jan 1, 1972

By C. E. Semler

A 5 year test program, involving on-line, in-vessel exposures at Barrick Goldstrike Mines. Inc. has provided valuable information and experience about the materials and designs for brickwork linings in pressure oxidation autoclaves. A variety of brick and mortar products have been evaluated. Properties before and after exposure are used to document the performance. Benefits have included the development of a new silicate mortar improved understanding of brick requirements and increased autoclave operating time between maintenance shut-downs. More improvements are expected in the future based on further information from the test program.

Jan 1, 1997

By James L. McGregor

St. Joseph Lead Company has been paying incentive bonuses for well over 40 years. In 1958 almost half of St. Joe's 1,860 employees in Southeast Missouri received some form of incentive bonus in addition to their guaranteed wages. There are very few payroll jobs in St. Joe s Southeast Missouri organization that lend themselves to a reasonably good measurement of production or quality, or both, where an incentive bonus is not paid. The term "Incentive Bonus" is used to differentiate betwen bonuses that are based on quantity or quality of work, and those that are merely additional pay of a standard amount per hour or day because of an employee being temporarily assigned to some unusual task, An employee temporarily assigned to a job where the working conditions make the job performance unusually difficult or where a special skill is used is often given a bonus of some standard amount per hour or shift in addition to his usual rate. This is merely a convenient way of paying something extra without disturbing the normal rate structure. Actually, it is differential pay similar to that almost universally paid for evening and night shift work. Bonuses of that type are not being considered in this paper. The basic reason or theory for paying incentive bonuses 9s to get improved production at lower cost, Unfortunately, it is often difficult, if not impossible, to find a yardstick by which it can be definitely proved that a particular bonus plan is accomplishing its purpose, It becomes, then, a matter of judgment on the part of management personnel as to the value of the bonus plan. The fact that St. Joe Lead Company has continued to pay bonuses for over 40 yews and has increased the number of bonus schedules used attests to a definite belief that they are beneficial to the company's successful operations.

Jan 1, 1960

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 Steve Kral

The mining industry has waited a long time for the resurgence in commodity prices and demand for its products that it is now experiencing. Base and precious metals prices have reached levels not seen before. Coal prices have also shot up. And there are encouraging signs in the uranium market. China’s nearly out-of-control economic growth is said to be the leading driver for much of this resurgence. But demand for energy, metals and building materials in the United States and elsewhere are also major factors. The result is that expansions and new mines for nearly every commodity are in the works.

Jan 1, 2005

By D. R. Spears

The U.S. Bureau of Mines has developed a Fast Air-injected hydrocyclone-Shallow Tank (FAST) flotation system. Conventional flotation cell kinetics are a compromise between two conflicting requirements, the need for an agitated zone for rapid bubble-particle collision, and a quiescent zone for bubble-pulp separation. The Bureau of Mines has designed a flotation system in which bubble-particle collision and bubble separation are carried out in two discreet unit operations. A bubble slurry was mixed with an ore slurry at a high rate in a modified air-injected hydrocyclone for rapid bubble-particle collision. The mixture was then fed into a unit specially designed for rapid separation of the bubbles from the pulp. A conventional flotation cell required 2.8 min to obtain 90 pet recovery at a 7-pct Cu rougher concentrate grade, whereas the FAST flotation system can obtain 85 pet recovery with a 13-pct Cu rougher concentrate grade in 0.28 min, and 92 pet recovery with a 7-pet Cu grade in 0.56 min. The Bureau's FAST flotation system is adaptable to a wider variety of flow sheets and could potentially allow for replacement of conventional flotation cells with smaller and faster units.

Jan 1, 1991

By R. Asamoah, K. B. Owusu, G. Abaka-Wood, W. Skinner

The hostile nature of industrial autogenous (AG)/semi-autogenous (SAG) mill operation necessitates the need for robust and reliable online measurements. Mill slurry density is regarded as a critical variable and requires a suitable range for grinding efficiency. In this work, mill acoustic sensing of five different slurry densities (50, 60, 70, 80 and 90 wt.% solids) was investigated using a laboratory-based AG/SAG mill. The results showed that slurry density of 70-80 wt.% solids gave the highest mass of -75μm particles and similar acoustic intensity. The mill acoustical level increased continuously coupled with energy reduction as a function of increasing slurry density, an indication of potential realtime measurement.

Mar 2, 2022

By Myles E. Robinson

Significant changes in the markets for coal have taken place since World War II, As used in this study the term ?coal? will refer to bituminous coal, The anthracite industry in size, characteristics, and problems differs materially from the bituminous coal industry, These changes have both influenced and been influenced by the mechanization of mines, and by decreased distribution costs, especially in transportation. It is the purpose of this paper to examine these post-war changes, to assess their impact upon the production and distribution of coal, and to explore future market developments in the light of past and present trends and relationships. The layman lacks adequate informatian on the production, demand, and distribution of coal. There are two reasons for this. First, there is a relative lack of statistics coveting the industry, Coal operators and distributors are not required to file with any government agency the type of much more complete statistics filed by the railroads and public utilities with national and State agencies. The Bureau of Mines assembles much useful information on the coal industry, but several areas, including that of investment and finance, have no central depository which can be used to keep the public informed of the nature and extent of the industry and its problems.

Jan 1, 1964

By Dafydd Chandler, Milissa Hirst, Charles Hurst, Gary Snyder, Leszek Glodkowski

The Delaware County Regional Water Quality Control Authority (DELCORA) will be adding tunnel infrastructure to its wastewater conveyance system. This program involves the construction of a conveyance/storage tunnel and related facilities. The proposed 12- foot to 14-foot (±) finished diameter, TBM mined deep rock tunnel spans over 8.5 miles and lies approximately 80 ft-120 ft below the surface. The system is connected to the surface by at least five vertical online shafts and one offline shaft with associated 800ft long adit. This paper provides project details including data on the geologic conditions in which the tunnel will be constructed.

Dec 1, 2022

By J. A. Marts, R. C. Gilmore, Jr. Bogin, S. A. Saki, J. F. Brune, J. W. Grubb

The main purpose of mine ventilation design is to provide sufficient quantity and quality of air to the workers and to dilute methane and other contaminants. It is generally perceived that the additional air along the longwall face will improve methane dilution on the face and in the tailgate. However, computational fluid dynamics (CFD) modeling efforts at the Colorado School of Mines (CSM) under a National Institute for Occupational Safety and Health (NIOSH) funded research project have found that higher flow velocities along the longwall face are shown to increase the pressure differential between the gob and longwall face allowing more methane to be entrained in the active face and tailgate (TG) area, thereby negating the dilution effect. The increased face ventilation causes an increase in pressure along the headgate side which allows more oxygen to ingress into the gob area, thereby increasing the amount of oxygen available to form explosive methane air mixtures in the gob and to support spontaneous combustion of the coal. Two things are happening at two different locations along the longwall face, increase in pressure as the flow enters the active area cause an increase in pressure which forces more oxygen into the gob, but as the flow is developed along the longwall face, the higher velocities causes greater pressure drop allowing methane to enter the active face further downstream from the headgate (HG) towards the tailgate side. In this paper, a parametric study will be presented to discuss the effect that varying the face air quantity has on methane concentrations in the tailgate and formation of explosive gas zones (EGZs) in the gob. Counter to conventional wisdom, it appears that increased longwall face air quantities may increase the explosion hazard as they result in increased EGZ volumes in the gob, along with increased methane quantities in the tailgate return.

Jan 1, 2015

By M. Tamlin

The state of the lithium mineral industry is closely linked to the performance of the glass and ceramic industries and to the overall economy. Demand for the glass/ceramic products in Europe, Asia and North America remained strong during 1999. This was due to a slight improvement in the economy during the latter half of the year. Consequently, demand for lithium minerals was firm, with a positive outlook. The major economic minerals for lithium are spodumene, petalite and lepidolite. The latter was once the primary mineral. But its importance hasdeclined since the 1960s. The lithium industry consists of two different segments: •The lithium minerals segment mines from hard-rock deposits and physically processes the material to high-grade concentrates. •The lithium chemicals and metal industry segment. The major feedstock for specialty lithium chemicals was previously high-grade spodumene ore converted to lithium carbonate. However, most lithium carbonate is now sourced from salars in North and South America.

Jan 1, 2000

By S. P. Sandoval

In 2002 the Freeport-McMoRan Technology Center undertook research to develop a lower-cost alternative to guar for cathode smoothing in copper electrowinning. The work was conducted at the Technology Center?s SXEW Test Facility located in Morenci, Arizona. Bench-scale copper electrowinning cells were designed and implemented to screen a number of potential polymers for cathode smoothing. These included modified polysaccharide polymers that were nonionic, cationic, and anionic in nature.

Jan 1, 2010

By R. E. MacDougall

Very few mineral properties spend their entire lifespans from discovery to depletion in the hands of one owner. More likely, properties will have several owners, and partial interests may change quite often. Similarly, mineral companies are bought and sold with frequency, in recent years at what appears to be an accelerating rate. The reasons for selling a property can be manifold -need for additional capital in other parts of the business, need for development capital, realization of a large gain at a perceived high point in the market, pessimistic commodity outlook, retirement of principals, or resolution of estate problems. Regardless of the reasons for a sale, there are specific steps that logically follow. Spruce up the business, package the information, market the property, negotiate the terms, close the sale, and make sure it stays sold. Adherence to certain very basic ground rules in property sales can maximize the profits and minimize the effort.

Jan 1, 1990

Application of flotation for the removal of hydrophobic compounds from soils was studied. Bench scale flotation tests were conducted on artificially contaminated soil, using both conventional mechanically agitated machine and flotation column. Flotation parameters tested include surfactant collector type, conditioning time, flotation time, surfactant dosage, pulp pH, solid/liquid ratio in conditioning and pulp temperature. It is found that with conventional flotation 74% removal of the contaminant was achieved from soil particles in the range of 75-830 µm; with column flotation up to 80% of oil could be removed from the 250-830 µm soil fraction, and 65% from the 75-830 µm fraction. Flotation was found to have considerable potential for cleaning up contaminated soils.

Jan 1, 1998

By C. W. Armbrust

At FHC Gold Company's Paradise Peak Mine gold and silver are produced. Precious metals recovery rates are very satisfactory along with the recovery and production of a relative high volume of mercury. At Paradise Peak precious metals are recovered via the Merrill-Crowe process and delivered to the refinery area as a mercury-bearing precipitate cake. The recovery of mercury is then obtained through a vacuum retort system. The balance of the material is mixed with fluxes and then melted and cast into dore' bars for shipping. Issues of retort capacity and concerns over efficiency led to research into the retort process itself.

Jan 1, 1990