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By A. B. Cecala

The US Bureau of Mines has designed and evaluated total mill ventilation systems (TMVS) at two mineral-processing operations. Both systems have proven proficient at cost-effectively reducing respirable dust levels throughout the mills. An 11.8-m3/sec (25,000-cfm) system installed at a clay-processing mill provided about 10 air changes per hour(acph). This system reduced respirable dust concentrations by about 40% throughout the mill building. The second evaluation was performed at a silica sand operation. Tests were performed with 23.6 and 47.2 m3/sec(50,000 and 100,000 cfm) of ventilation to the mill building, corresponding to 17 and 34 acph. Average mill-wide respirable dust reductions were 36% and 64%, respectively. This work was done to determine general guidelines and design criteria for operations that may be interested in implementing TMVS. TMVS should be designed to draw clean make-up air in near the base of the mill. This air provides general purging and may clear some dust-laden areas throughout the mill structure. It is discharged at or near the top of the structure. Without the TMVS, dust can exit the building through open doors, windows, etc. and contaminate outside plant workers. This dust can also be recirculated back into the mill building causing additional contamination problems. TMVS is not a stand-alone system. It is a supplemental technique to assist other localized dust control systems (Mody et al.,1987).

Jan 1, 1995

By Michael D. Loy

This paper examines the computerization steps of United Coal Company of Bristol, Virginia. OVERVIEW Producing close to 7,000,000 tons per year, United Coal Company is one of the most interesting mining companies in the east. Their approach to mining reflects a dedication to modern technologies and extraction methodologies. With varying amounts of production coming from four divisions (a fair amount of production comes from contract operators) and over a billion tons in recoverable reserves, United rests heavily on the planning and engineering efforts of a centralized engineering group. Although each division relies on its own engineering personnel for day-to-day management and operations, long range planning and reserve management is conducted at the corporate engineering level. This group, while extremely competent and efficient, is relatively small (7 people), when compared to the needs of a large mining company.

Jan 1, 1985

By John C. Draper

Little precise information is available on the effect of mining on the surface topography. It is often assumed that after mining the surface will simply sink. This is not an infallible conclusion as is well illustrated in two of the three examples herein. This paper describes the results of an attempt to precisely measure the surface movement in the area around coal pillars left in place for three oil wells in a completely mined and caved area at the Harwick Mine of the Duquesne Light Company. The dates when the various measurements were made are shown on the data sheets and indicate the rate of surface movement. These oil wells are identified as wells Nos. 2, 3, and 6. This mine property is located on the north side of the Allegheny River at Cheswick, Pennsylvania, and extends in a northerly and westerly direction about five miles. The three well pillars are situated on the westerly side of the Bessemer and Lake Erie Railroad some 2,000 feet from Rural Ridge, Pennsylvania (Fig, 1).

Jan 1, 1964

By R. J. Thompson

Well-designed and maintained haul roads are the key to minimizing truck haulage onroad hazards and costs, as well as increasing productivity. In practice, however, designing and managing a haul road for optimal performance is often difficult to achieve, especially when resources assigned to design and construction are constrained. By understanding how a road design is developed from geometric, structural, functional and maintenance considerations and, critically, the interplay between these components in design and operation, optimal performance can be achieved. This paper briefly summarizes the evolution of mine haul road design, from the seminal USBM work of Kaufman and Ault in 1977, through to current geometric, structural, functional and maintenance management design components. These augmented design and management guidelines have been developed over the past decade, both in response to the requirements of mine operators for safer and more efficient haulage systems, the truck manufacturers’ requirements for a more predictable and controlled operating environment and the recognition of human factors as a significant contributor to haulage accidents. While the human factor is the most problematic to address in a road design, the paper shows that the more that is known about human error, the better a road can be designed to accommodate those actions or non-standard practices that would, on a poorly designed road, invariably escalate an error into an accident.

Jan 1, 2010

An AFM has been applied to study in situ the adsorption of oleic acid on fluorite in aqueous solutions. The AFM images show that fluorite surface becomes smoother with the adsorption of 7 × 10-5 M oleic acid solution at pH 9. Force measurement shows that fluorite is strongly positively charged in water at pH 6, suggesting a neglectable surface carbonation of fluorite. The adsorption of oleic acid at pH 9 renders fluorite more and more negatively charged. The surface morphology change of fluorite as shown by the AFM images suggests that oleic acid chemisorbs on fluorite at pH 9. Increasing temperature can help increase the adsorption of oleic acid on fluorite. It may also improve the lateral polymerization of unsaturated oleic acid on fluorite as suggested by the smoother mineral surface in oleic acid solutions at an elevated temperature.

Feb 23, 2014

By C. E. Davis

The Jamaica Mining Legislation requires the bauxite companies operating in the island to reclaim all mined-out lands (except those legitimately excluded) to the level of agricultural or pastoral productivity, which existed prior to the commencement of mining. If it is not possible to reclaim a mined-out area the companies are required to reclaim an equivalent area of some other land which had not previously been used for agricultural purposes, or alternatively, pay to the government the sum of $120 (US) for every acre of land mined in the particular sector. In the seventeen years since the programme commenced the companies have in general chosen to reclaim most of the mined-out lands, rather than the cheaper alternative. However, the ultimate success of the programme will depend not only on actual reclamation per se but moreso the productivity of the rehabilitated lands. There are a number of reasons why the accent has to be placed on productivity of the lands. The first is that Jamaica is a small country (4,450 square miles) with a population of nearly 2 million people. Because of its mountainous terrain it is estimated that only 35% of the land area is cultivable in crops and pastures; hence this limited area, as well as that which can be reclaimed, must be made highly productive in order to support local and export demands. The Mining companies own over 200,000 acres of land, and of this acreage, it is conservatively estimated that about 75,000 will be affected by mining and will be reclaimed. As such, the use of the land after mining can have an important bearing on Jamaica's future agricultural productivity. The second reason is that a significant amount of the land now owned by the companies was purchased from thousands of small

Jan 1, 1972

By G. C. Presley

With plant construction scheduled for the Spring of 1997, U. S. Zeolites will become the new source for quality in natural zeolites. The company will selectively mine, dry process, package, and market a very high quality clinoptilolite possessing many unusual properties. These unusual chemical and physical properties provide a multitude of industrial, commercial, and consumer applications. Extensive testing has determined many potential applications.

Jan 1, 1997

By A. L. Hinde

Ideally, mill circuits should be controlled so that excessive random disturbances are reduced in frequency and amplitude. It is difficult to derive an objective measure of the effectiveness of any chosen control strategy. Often, the response of the circuit to pulse or sinusoidal disturbances is used as a measure of the effectiveness of control, but this is not adequate in many circumstances because such disturbances bear little resemblance to those that occur in practice, and such an approach cannot be easily related to the profitability of the reduction process. A superior approach appears to be the application of the theory of stochastic processes. This theory permits both real process disturbances to be modelled accurately, and useful objective functions for control to be derived. A test of the usefulness of stochastic theory in mill control was made on the gold ore milling circuit shown in Figure 1. This circuit was fed with an ore which had a liberation characteristic such as that shown in Figure 2. It is simple to show that, for such a liberation characteristic, the recovery of valuable mineral will vary as the standard deviation of the particle mass-size distribution varies even though the mean particle mass-size is kept constant. Similarly it may be shown that excessive perturbations in the circulating load in a milling circuit such as that shown in Figure 1 can affect liberation. Figure 3 shows how, as the cyclone feed density increases and the sump water addition decreases at constant sump level, the cyclone operation becomes unstable and the discharge "ropes? with a consequent catastrophic coarsening in product size. By minimising the variance of the circulating load it is possible to reduce the probability of initiating instabilities of this nature.

Jan 1, 1977

By Frank McKinley

This paper discusses the basic requirements covering the area between the initial discovery of a deposit and a decision as to whether or not the deposit will support an economically sound mining venture. The procedure for gaining the necessary information and the sequence of steps is in .some respects parallel to gaining like information on deposits other than the sand type. For the sake of simplicity the stages and sequence are presented as follow: first, the initial reconnaissance drilling; second, the exploration drilling to permit initial ore body estimates; third, metallurgical testing; fourth, the estimate of plant and operating costs; and last, the economic balance. The objective of the reconnaissance drilling is to collect sufficient information to reach a decision as to the advisability of further exploration or the abandonment of the area. This initial phase will comprise, in addition to some drilling, a thorough reconnaissance of the area, a study of the best geological and topographic maps of the region, and a study of any literature available, all under the guidance of a geologist.

Jan 1, 1958

By D. Pearson

About 15,000 tonnes of zinc per year is present in the dusts and fumes produced in electric arc and BOS steelmaking, secondary copper refining and brass ingot making. Apart from the use of some copper-smelter fumes for zinc chemicals manufacture, zinc is not recovered and their disposal by landfill entails some risk of pollution by leach-out. The paper describes processes for recovering the zinc based on leaching and electrowinning. It was shown that the procedures normally employed for purifying zinc-electrolytes derived from primary sources are sometimes ineffective for secondary materials. Alternative process routes are proposed. Source materials were leached with acidic or alkaline reagents and solvent extraction was employed for electrolyte purification in addition to the usual techniques involving precipitation. Examples of integrated flow sheets for specific source materials are presented.

Jan 1, 1980

By Alvin D. Cronberg

Silica flotation with amine salts has been a commercial process for years in certain non-sulfide mineral systems. Phosphate rock and feldspar deposits are notable examples. Generally, the quartz is clean and coarse. Primary amines and imidazolines are used, usually in a mole weight range 250-300, ad often fairly impure grades of collectors are satisfactory. As the production of magnetic iron concentrates grew in Michigan, Minnesota, Canada and in foreign locations, the iron mining companies began to explore amine flotation of silica to improve these concentrates. Many of the mining companies, as well as reagent suppliers, government laboratories and university research teams, had already studied amine collectors for silica, but the application to magnetic iron concentrates presented a real commercial opportunity to apply the art. Amine flotation of silica has been accomplished by simple addition of a flotation cell, and possibly a regrind mill, at the end of the magnetic concentration process. The flotation system gave the mill operator a flexible method to control final grade caused by ore variations in the feed. It increased iron content with lower silica, which resulted in lower freight costs per unit Fe and better pellets for blast furnace use.

Jan 1, 1968

By R. R. Klimpel

This paper describes a series of mechanical flotation cell results run with various chemical reagent schemes designed to economically improve the flotation performance associated with selected industrially available coals. The emphasis is on the identification of practical flotation methods of processing coals containing unusually coarse and/or fine feed sizes, of increasing the recovery of oxidized and/or difficult to float coal, and of increasing the selectivity of coal over pyrite in high sulfur coals.

Jan 1, 1991

By C. West

Structured or embossed HDPE and LLDPE geomembranes have been available to mine owners and designers for over ten (10) years. As many owners and designers discover and demand the consistent high quality characteristics of this type of geomembrane due to the unique manufacturing process, the use of these materials in new mines, mine expansions and final closure designs has steadily increased. Structured liner materials are available for double lined and final cover systems and are revolutionizing the way ponds, pads and final closures are constructed. This paper will discuss the structured or embossed geomembrane concept and manufacturing process. Additionally, the paper will present comparative testing illustrating the major advantages of using this type of product in these types of applications. Both technical and economic advantages are illustrated. The cost savings include lower installation costs, less material used, and third party inspection times not to mention better performance. These new systems will be presented.

Jan 1, 2011

By G. Michael Lloyd

The term phosphate beneficiation often conjures up visions of processing technologies that physically separate the phosphate rock from some impurity and do not result in a change in the chemical nature of the phosphate rock. However, when we consider hydrometallurgical processing as a phos¬phate beneficiation technique we have to include all chemical treatments that convert phosphate rock into a more useful product. With most of the phosphate rock mined being used for fertilizer pro¬duction, the best known and most widely employed hydrometallurgical process is wet process phospho¬ric acid manufacture. In general, all phosphate rocks are so insoluble that there is no physical treat¬ment that will allow the phosphate content to be used by vegetation in a timely manner. However, after chemical treatment, 100% of the phosphate is readily available for vegetation nutrition. If there is a chemical beneficiation process that could be considered the standard method of treat¬ing phosphate rock it would have to be the wet pro¬cess for phosphoric acid production. In this process finely ground phosphate is reacted with sulfuric acid to give phosphoric acid and phosphogypsum. The phosphogypsum crystals are removed from the phosphoric acid solution and discarded; the phos¬phoric acid is further processed to give the finished fertilizer product. The primary reason that this pro¬cess was adopted so widely is because the phosphogypsum solid that is formed can be easily separated from the phosphoric acid, thereby removing the calcium portion of the phosphate rock and the sul¬fate portion of the sulfuric acid. Other acids have been used to treat phosphate rock but nitric acid is the only other acid used commercially. Nitric acid gives a mixture of phos¬phoric acid and nitrates that can be further pro¬cessed into N-P fertilizers, but the range of N/P grades that can be produced is limited. Hydrochlo¬ric acid has been used to react with phosphate rock, and it can be used to generate a pure phos¬phoric acid but only after solvent extraction to separate the calcium chloride from the phosphoric acid. And then there is the problem of what to do with the calcium chloride. The acid that has received the most attention as a substitute for sulfuric acid is phosphoric acid. In this process, the phosphoric acid reacts with the phosphate rock to give a mono-calcium phosphate solution. This process does not dissolve all the impurities in the phosphate rock, and these solids can be removed from the solution before sulfuric acid is added to convert the soluble calcium to insoluble phosphogypsum. Despite all the claimed advantages, this process has not found favor. A suc¬cessful application of this process to treat some of the lower grade phosphate rocks being used today would seem to have some distinct advantages. Other beneficiation schemes have been pro¬posed or practiced on specific phosphate rocks on a limited scale. These include calcination followed by water leaching to remove lime, weak acid

Jan 1, 1999

By B. Andersen

An accurate knowledge of Interactions among mineral particles and between such particles and dissolved and precipitated species Is Important in developing efficient separation processes. In this investigation interactions in Florida phosphatic clay waste, that are relevant to dispersion and selective reagent adsorption, the two main prerequisites for selective flocculation, were studied. Initial studies with artificial slimes, consisting of pure clay and phosphate minerals, showed dispersion of artificial slimes to be relatively easy. The problems that were encountered during selective flocculation of the artificial slime were due to unselective polyacryllc acid adsorption on clay, which was caused by the presence of multivalent calcium ions on the exchangeable cation positions on the clay surfaces. This problem could be solved by exchanging calcium for sodium, which reduces the interaction between the polymer and the clay surface. This procedure, however, was not successful for mineral mixtures. Natural slimes were found to be much more difficult to disperse. This was attributed to the presence of cementing materials such as humic substances and Ai and Fe (hydr)oxide precipitates. Selective removal of these cementing materials resulted in good dispersion and partial separation. Further increase in separation of natural slime is likely determined by the presence of calcium on the clay surfaces, as was found for the artificial mixtures.

Jan 1, 1992

By M. J. Langley

Zinc ores were first discovered in Tennessee in 1856 at Jefferson City where a deposit of oxidized ore became known as the Mossy Creek Mine. From that time until 1913 small scale attempts at prospecting and mining were made in various parts of the district. The actual systematic development of the zinc deposits dates from 1913 when the American Zinc Company started operations at Mascot. Six mines are in operation by three companies and a seventh mine is being developed by a fourth company. The total daily production from the field is 11,000 tons of crude ore, which grades from 3 to 6 per cent zinc. Most of the ore bodies are large and ramiform, resembling asyrmetrical networks in which the ore shoots form channel like branches with areas of non-comercia1 rock, called blank islands. Most of the orebodies are adapted to large scale mechanization.

Jan 1, 1962

By S. Veeramasuneni

The interaction of soluble salt particles in their saturated brines is of interest from both a fundamental and practical perspective. The state of dispersion/aggregation of alkali halide particles as determined by optical microscopy can now be described based on non-equilibrium electrokinetic measurements for alkali halides. These results indicate that the sign of the surface charge has a significant effect on the extent of particle dispersion/aggregation. Atomic force microscopy (AFM) is now being used to directly measure the interaction forces responsible for the stability of these alkali halide aggregates observed in optical microscopy studies. These experimental results can be explained based on the interfacial polar interaction theory. In this regard the nature of such particle interaction forces at high ionic strengths are examined to improve our understanding of these systems.

Jan 1, 1997

By J. M. Mercier

Approximately seven (7) years of recent intensive mining activity in the Wasatch Plateau Coal Field of Utah has revealed distinct geologic patterns which, at times, profoundly influence reserve estimates, coal quality, mine layout, and reserve accessibility. Mine planning, economic feasibility, and resource recovery activities by Getty Coal Company utilize a multi-faceted approach by necessity when evaluating Utah properties. Two specific operating mines offer examples of the affects of adverse geologic conditions on mine operation and project economics.

Jan 1, 1984

By J. Douglas

The past year has been a strange one for the fertilizer industry of the world and the United States. Listening to news stories, you would think the sky is falling on the world's agriculture and probably conclude that we should have had an exceptionally poor fertilizer season. In some respects, we did. Prices were low, profits were low, and in some cases nonexistent, but volume was good. We heard much in the press about the farmers' credit crunch. The truth of the matter is that only 6.6 percent of the U.S. farmers have debt-equity ratios of 70 percent or more, and a large percentage of our farmers have absolutely no debt but operate entirely on their own cash assets.

Jan 1, 1985

By Yu-ren Jiang

Novel compounds of hydroxycarbamoyl carboxylic acids, including 2-hydroxycarbamoyl -3-methlcyclohexane carboxylic acid (HCMC), 2-hydroxycarbamoylmethyl decylen-4-yl carboxylic acid (HCDC) and 2-hydroxycar-bamoylmethyl tridecylen-4-yl carboxylic acid (HCTC) were synthesized. The flotation behaviors of diaspore, kaolinite and illite using these compounds as collectors were investigated. The flotation results revealed that the floatability of the minerals was, in descending order, diaspore and kaolinite, followed by illite, and the ability to collect the minerals was, in ascending order, HCMC and HCDC, followed by HCTC. At a dosage of 2×10-4 mol/L, both HCDC and HCTC show a strong ability to collect diaspore and a weak ability to float kaolinite and illite. The flotation recovery of diaspore is over 90% and that of kaolinite and illite less than 30%. Moreover, Fourier transform infrared spectroscopy (FTIR) spectrum and zeta potential, as well as the adsorption amount, indicated that the adsorption interaction between HCTC and diaspore was primarily a kind of chemisorption in the form of chelate rings, while the interaction between the collector and aluminosilicate mineral was dominated by physisorption. It was concluded that the novel hydroxycarbamoyl carboxylic acid compounds are highly selective collectors for the flotation of diaspore vs. aluminosilicate minerals.

Jan 1, 2011