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By S. Veeramasuneni

The sign of the surface charge for alkali halides in their saturated brines has been established from non equilibrium electrophoresis measurements and on this basis the flotation response of alkali halides was explained based on the adsorption of oppositely charged collector colloids by heterocoagulation. These surface charge results for alkali halides are generally as expected from simplified lattice ion hydration theory with some exceptions, specifically LiF, KCI, NaCl, KBr, RbBr, KI, and Rbl .The presence of natural oxygen defect states in the crystal lattice and the inaccuracies involved in the gaseous ion hydration free energy values used appear, in past, to be responsible for these deviations. The presence of natural oxygen defect states in KCI, KBr, RbBr, and Rbl as characterized by UV Nis absorption, was found to account for their anomalous surface charge. Further, other positively charged alkali halides, LiF, NaCl and KI, were found to be free of oxygen defect states. Nevertheless, oxygen defects can be created in these alkali halides to make them negatively charged and has been demonstrated for NaCl. Such negatively charged NaCl can be readily floated with positively charged amine collector colloids thus confirming the surface charge/collector colloid adsorption theory.

Jan 1, 1996

By R. A. Allwes

In-plane bending and torsion tests were conducted on full-scale masonry walls to evaluate three post-reinforcement designs. The designs were developed to minimize longwall mine subsidence damage to existing residential masonry foundations. The bending tests show that vertical and horizontal post tensioned tendons significantly increase the resistance of a masonry wall' to in-plane bending. The torsion tests reveal that post tensioned tendons increase a masonry wall's limit of deformation but do not increase its torsional stiffness. The torsion tests also show that the masonry units minimally contribute to the torsional stiffness of a masonry wall.

Jan 1, 1995

By S. Bahrampour

One of the basic requirements for designing an optimized rock support for an underground opening is having reasonably enough geological information. It is often financially impractical to obtain detailed geological information about the rock surrounding the excavations. The geological and geotechnical information which are obtained during the construction phase are also usually inadequate and need periodic operation stoppage. Penn State University- J.H. Fletcher & Co. joint venture is to improve the existing instrumented roofbolter so that the 3D geological and geotechnical map of the rock mass surrounding the underground working can be generated real-time as the data is being collected. This information will also be used to design appropriate support for different sections of mines. In this paper, recent results in improving the performance of the measurement while drilling system will be discussed. Moreover, updates related to borehole probing methods for estimating the properties of the rock masses will be presented.

Feb 23, 2014

By Yves C. Lizotte

Although blasting remains the most inexpensive method of fragmentation in hardrock mining, the significance of the costs of blast-induced rockmass damage in terms of mining efficiency and safety is becoming increasingly recognized. There is no straightforward and systematic method of adequately measuring blast damage in on-going mining operations. This paper considers various techniques available to measure blast damage, making particular reference to recent underground hardrock mine studies. It concludes by proposing a damage audit procedure for integration into routine mine production control.

Jan 1, 1996

By G. V. Sullivan

As part of its program to conserve domestic mineral resources through advancing mineral resources technology, the U.S. Department of the Interior, Bureau of Mines, conducted investigations to determine the feasibility of recovering high-grade barite concentrates, suitable for use as well-drilling mud, from current and old waste pond materials and materials bypassed in present mining operations. Flotation studies of waste pond samples from Missouri and Nevada yielded barite concentrates containing over 95 percent BaSO4 with recoveries of 86 percent and 96 percent, respectively, of the barite in the flotation feed. Flotation studies of a hard-rock sample from Georgia, currently bypassed in mining, yielded a barite concentrate containing 97 percent BaSO4 with an attendant recovery of 97 percent of the barite.

Jan 1, 1980

By Zhe Wang, Tichang Sun, Yongqiang Zhao, Zhengyao Li

Coal-based reduction followed by magnetic separation is a promising technology for processing refractory iron ores. Analysis of the size distribution of metallic iron particles is an effective approach for exploring the mechanisms of coal-based reduction. As metallic iron particles exhibit very complex shapes compared with nature ores, approaches for measuring and characterising metallic iron particles still remain unclear. In this study, the size of metallic iron particles was measured and characterised using manual point-counting by optical microscopy technics and image analysis. The effects of CaF2 as an additive on behaviour of the particle size distribution (i.e. mean size and cumulative frequency distribution) were also determined. Results indicate that CaF2 had a significant effect on the growth of metallic iron particles. When the CaF2 dosage increased from 0 to 8%, the mean size according to the area method increased from 9.03 to 16.28 μm, while the promotion effect gradually weakened and generated many fine metallic iron particles when the CaF2 dosage exceeded 8%. An increase in CaF2 dosage also led to cumulative distribution curves gradually shifting to the right mainly because F− can break the crystal structure of each phase during the carbothermic reduction of titanomagnetite and reduce the stability of the lattice structure, thus reducing the melting point and accelerating the growth of metallic iron grains. Compared to different measuring methods, the area method is a more suitable approach for measuring and characterising the size of metallic iron particles.

Sep 18, 2020

By B. J. Arnold

Coal blending inherently means homogenizing a mixture of coals so that, overall, the properties of the blend meet some specifications for maintaining power plant performance and emission requirements. In common practice, however, coal blending is at best coal mixing. If necessary, more sophisticated blending systems can produce a more homogeneous feed by using accurate weighing devices and on-line coal analyzers coupled with sampling systems. Blending can be accomplished at the mine, on stockpiles, and from bins, bunkers, and silos.

Jan 1, 1994

By Lana Alagha, Ashraf Alsafasfeh, Amal Al‑Hanaktah

As freshwater resources are becoming scarce, the use of seawater as replacement of fresh water is appealing in order to make mineral processing operations more sustainable. Since froth stability plays a critical role in determining the performance of flotation operations, there is an urgent need to study the effect of frother dosage and seawater on froth stability. In this study, flotation tests in seawater were conducted to examine the effect of frother’s dosage (MIBC) on the froth stability and flotation performance of low-grade phosphate ore. The stability of the froth layer was assessed by measuring the froth growth velocity and the froth maximum height at equilibrium. Results indicated that the best flotation performance was obtained at 75 g/ton of MIBC where ~ 90% of phosphate minerals were recovered. At this recovery value, the concentrate grade was determined to be ~ 70%. Results from froth stability experiments showed that the stability of the froth layer increased by increasing MIBC dosage. At MIBC dosage of 75g/ton, the calculated values of dynamic froth stability and the froth height were ~ 0.4 cm/sec and 16 cm, respectively.

Jan 17, 2024

By Patricia Curtis Petty

Thirty years ago, the appearance of a female mining engineer, geologist or miner in a company, union or mine environment would have been unthought of, unwelcomed and violently opposed. Twenty years ago, the intellectual perception of the news that women were interested in becoming mining engineers, geologists and miners had been accepted by the industry-but no one wanted to be the first to hire one of these exotic creatures. Ten years ago, those who had been most vehemently opposed to the philosophical idea of women working in these areas were faced with competent, productive engineers, geologists and miners-who only incidentally happened to be women-and began hiring them. Historically, of course, one can always find the isolated individual who worked in these areas-the first female graduate of the Colorado School of Mines with a mining engineering degree graduated in 1903-but the concept of woman as professional engineer was very slow in arriving in the United States. The few who worked as miners generally worked in small family enterprises, such as some of the coal mines in both Eastern and Western United States. Others accompanied husbands or sons into wilderness areas searching for gold and other precious metals.

Jan 1, 1984

Factors which cause thiourea consumption in gold-leaching systems include adsorption by gangue mineral particles, complexation with base metal ions, thermal degradation, and oxidation by air/ferric iron. Of these factors oxidation by ferric iron is the most significant factor. Of course, ferric sulfate is desired as an oxidant for the gold leaching reaction, but an excess of ferric sulfate leads to high thiourea consumption. In this regard, the rate of gold leaching by thiourea must be balanced against the rate of thiourea decomposition. It is important to note that the thiourea decomposition reaction in ferric sulfate solution is relatively slow in pure solutions and has been found to be first order with respect to both thiourea concentration and total ferric iron concentration. However, when mineral particles from gold-bearing ores or concentrates are present, the decomposition rate can become quite significant. As might be expected, the catalytic activity of mineral surfaces varies with particle composition and size. Experimental results are discussed with respect to the consumption of thiourea.

Jan 1, 1997

By Rodger C. Smith

The topic chat has been assigned to me ?Economic and Political Climate of the Potash Industry? is a function of two basic facts: 1. Potassium is absolutely essential to plant and animal growth. Along with nitrogen and phosphorus it is one of three major plant nutrients, the three nutrients required in largest quantities for plant growth. 2. United States is unequivocally an "have not" nation with regard to potassium. Quantity of potassium ores is limited and, more disturbing, the cost of production at all U.S. potash mines is marginal in comparison with the major producing countries, i.e. Canada and U.S.S.R.

Jan 1, 1983

By William J. Stone

Large reserves of coal and uranium exist in the San Juan Basin of northwestern New Mexico. The mining and development of these resources necessarily also involves depletion of area water resources and disturbance of the hydrogeologic framework. In an effort to better define the water resources and hydrogeologic framework of this region, the New Mexico Bureau of Mines and Mineral Resources, the U. S. Geological Survey, and the State Engineer's Office are presently engaged in a cooperative study of the Hydrogeology and Ground-Water Resources of Northwestern New Mexico. The purposes of this paper are to introduce our project, review tine coal and uranium resources of the San Juan Basin, and discuss the various hydrogeologic considerations recognized in their exploitation.

Jan 1, 1976

The General Purpose Simulation System (GPSS) is a computer simulation language that has been used for simulations of open pit haulage operations since the 60's. It is easy to learn, simple to use, and has a block-diagram structure that is amenable to load-haul systems. However, due to its lack of flexibility, there are situations where another language should be chosen. This paper reviews the characteristics and capabilities of both GPSS and FORTFAN with regard to open pit shovel and truck simulation. The relative advantages and disadvantages are highlighted and a case study presented along with comparative results from two computer models (one written in GPSS and the other written in FORTRAN).

Jan 1, 1986

By R. J. Jula

The process of treating granular activated carbon for return to service in the recovery of gold in Carbon in Pulp and Carbon in Leach circuits has been investigated. Carbons from four U.S.A. mines, one Canadian mine and one South African mine were characterized before and after regeneration. The use of thermal gravimetric analyses demonstrated the presence of inorganic compounds on the surface of the carbon. Thermal regeneration was investigated using factorial' analysis to determine the effect or interaction of furnace temperature, retention time and the use of supplemental steam. The operation of acid leaching prior to or after gold elution was investigated. The effect of water quenching, regenerated carbon was also studied. From the data obtained in this investigation, guidelines are given for effective regeneration operation.

Jan 1, 1985

By L. Sandbak

"CURRENT BASIS OF GROUND SUPPORT DESIGN ANALYSIS The current strategy used in determining what kinds of support are needed is based on empirical design charts (Grimstad and Barton, 1993). Figure 1 is an example of the topcut analysis used for a 14 foot wide (4.3 meter) drift, which is the current design width used for topcuts at TRJV mine. The majority of our topcuts are situated in ore of the Type IV and Type III weak rock class categories that necessitate the use of bolts, mesh and 2”-4” of shotcrete. This type of empirical chart gives excellent guidelines for the kinds of support, and it is based on case histories of civil tunneling and mining properties. It is a good starting point for determining the kinds of support needed, but not to the detail needed to optimize the number of bolts, type of mesh, or combination of types or strengths of shotcrete. This report is an attempt to help quantify the safety factor and optimum design parameters to include mesh and shotcrete as part of the design criteria and subsequent safety factor.SAFETY FACTOR ANALYSIS: BOLTS ONLY One type of safety factor analysis used at TRJV for the past 7 years is described as the “dead weight” method, developed by Pakalnis (2008). It involves the support of a conservative “dead weight” of rock held in place by bolts in which the depth of failure is approximated as a wedge whose height is one-half of the span. The failure or dead weight wedge resembles a triangular wedge that must be supported by the remainder of the bolts going through the wedge (see Figure 2).The support capacity of the system is determined by the bond strength of the bolts holding up the wedge, which is in turn based on the RMR. The method assumes the total support capacity is the sum of the individual bolt values defined by either the breaking strength or the bond strength of the bolts (whichever is lower) passing through the failure surface."

Jan 1, 2017

By T. McWaters

Miami Copper Company began a block-caving operation in 1911 using a gravity mill to separate copper minerals from the Pinal Schist host rock. The tailing was deposited by the upstream method using perimeter launders and spigot valves in six canyons adjacent to the mill until 1932. In 1928 the larger and more distant Solitude tailing pile was developed which by 1932 was receiving all tailing except for upsets. In 1925 Miami Copper converted its gravity mill to flotation which began to produce higher sulfide copper recoveries.

Jan 1, 1990

By G. Bonifazi

In the present work the possibility to utilize the morphometrical and morphological characteristics of an articulate solids system in a slurry flow to monitorate and to control a continuous process is considered. This goal has been reached by mean of an optical system able to acquire, to handle and to process the pictorial information derived by a suitable hardware architecture designed to realize the best lighting, focusing and sampling conditions for the examined flow stream domain. The procedure has been tested using different flow stream slurries coming from different sections of a beneficiation plant. A suitable strategy and a consequent software architecture has been set up in order to assure to the system the necessary speed and the stability to achieve correct on-line measurements and control.

Jan 1, 1994

By J. O. Guthrie

Newmont has delineated a 600,000+ ounce gold reserve in the Cargo Muchacho Mountains. This is a desert range underlain by Proterozoic(?) Tumco Formation (gneiss) intruded by Jurassic granitic plutons, and cut by low angle shears of the late Cretaceous Chocolate Mountain Thrust event. Gold, associated with pyrite, quartz veinlets, and propylitic alteration, is emplaced along low angle shears. The mineralizing system, enriched in tungsten, copper, zinc and arsenic, was active during Eocene time. Gold reserves are found in eleven areas as moderate to high tenor deposits that may be mined by open pit and underground techniques. Eastmaque Gold Mines Ltd. is developing the deposit.

Jan 1, 1987

By Z. Yunquan

The flocculation and dispersion behaviors of microsize wolframite and quartz are systematically studied in this paper. For synthetic mixtures, the floc separatory method on gravity units--electromagnetic vibration table (EVT) and lifting column (LC), have been approached. Satisfactory results can be obtained with a weak shearing. A better metallurgical performance can also be achieved for natural ore slimes through the combined technique. The efficiency is better than that of single gravity separation. Finally, the mechanism has been investigated.

Jan 1, 1990

By R. J. Sweigard

Deep tillage is used widely as a Means of alleviating excessive soil compaction. There has been some concern that the voids created by deep tillage may collapse before a more natural soil structure develops, resulting in recompaction subsequent to deep tillage. A laboratory investigation was conducted to determine the feasibility of pneumatically injecting organic material into the voids during deep tillage to prevent any significant recompaction from occurring. Various amendments were injected into the soil in the laboratory using a small-scale ripping and injection system. Measurements were made of selected soil properties to evaluate the feasibility of this method.

Jan 1, 1993