Search Documents

By Dennis V. D’Andrea, Peter G. Chamberlain, James J. Olson, William C. Larson

Blasts designed for in situ copper leaching must produce adequate fragmentation and permeability for successful leaching. Copper recovery depends to a large extent on the particle size distribution created by the blast, the permeability in the blast- fractured zone, and the ability to maintain solution flow with a minimum amount of channeling. This paper presents the results of Bureau of Mines experiments where core drilling was used before and after blasting to establish the degree of fragmentation. Data are presented from tests at the Sierrita mine of Duval Corp., and also from tests at the Emerald Isle mine of El Paso Mining and Milling Co. Copper recovery is predicted from fragment size distribution data using a computer model. Data from several blasts are used to show how predicted copper recovery is related to powder factor.

Jan 1, 1977

By A. Cavero, M. Diaz

The annual rainfall at Minera Yanacocha's gold mining operations in northern Peru averages 1.2 meters. The influx of water into the operations is higher than losses to evaporation and by ore absorption which results in a positive water balance. To minimize water intake and maintain a balance, some special operating procedures are required, and a system involving diversion ditches, storm ponds, heap skirting and detoxification and treatment of excess water is practiced. An operation background is also reviewed at the beginning of the paper.

Jan 1, 1998

By Dipak D. Shah, Sajjan K. Jain

An interceptor sewer, 2103 linear meters (6900 Ft), 1.52 meter (5 ft) in nominal diameter, is installed by a direct pipe jacking system utilizing a remotely controlled fully automatic slurry shield machine called "Unclemole". The system involves placement of custom designed fiberglass pipe with Unclemole. The sewer alignment is along a heavily travelled thoroughfare in Staten Island, New York with invert varying from 20 meters (65 ft) to 28 meters (92 ft) beneath the road surface, and passes through soils of Glacial and Cretaceous origin. Dewatering was carried out at the jacking and receiving pits. Details of ground conditions, the pipe jacking system and method, and tunneling experiences are herein described.

Jan 1, 1991

By K. H. McDaniel

Eight mine weather stations (MWSs) installed at the Waste Isolation Pilot Plant (WIPP) to monitor the underground ventilation system are helping to simulate real time ventilation scenarios. Seasonal weather extremes can result in variations in the natural ventilation pressure (NVP), which can significantly affect the ventilation system. The eight MWSs, which previously collected and stored temperature, barometric pressure and relative humidity data for subsequent NVP calculations, were upgraded to provide continuous real time data to the site-wide central monitoring system. These data can now be utilized by the ventilation engineer to create real time ventilation simulations and can indicate trends that assist in the prediction and mitigation of NVP and psychrometric related events.

Jan 1, 1999

By Stephen H. E. Phillips, Michael J. Beus

A pneumatic impact breaker is used to fragment the rock at the shaft bottom, replacing the drill and blast cycle. A backhoe-type mucker removes the broken rock. The operators are in protective cabs below the bottom work deck in the shaft. Preliminary testing has been accomplished at underground and surface test sites in Arizona. Seven, approximately 6.4 m deep by 7.3 m-diameter (21 ft by 24 ft) test holes, (a total of 45 m (148 ft)), were recently excavated in various rock types, including jointed and massive quartz monzonite and rhyolite. An average advance rate of .4 m/hr (1.24 ft/hr) has been achieved. This includes breaking and mucking the rock. Further data is being sought from an in-shaft demonstration.

Jan 1, 1981

By St. E. Deák

Mining activities involve excavation from underground to the surface of large quantities of ore (e.g. uranium and its disintegration products) (Dumitrescu, 2002, 2007). Material with limited content of uranium, deemed as sterile or low-radioactive is mainly stored on the surface. These wastes modify the configuration of the disposal areas and affect the quality of the environment and the landscape. This paper presents both analytical and numerical models related to stability assessment of uranium mining waste dumps. It is focused on the calibration procedure of the numerical models, in order to minimize risk error during stability prediction and avoid long term environment pollution.

Jan 1, 2008

By Lynn B. Hales, Randy A. Yncbausti, Rick Smith

Object oriented programming has been developed to model the way we think about the world. It allows higher levels of abstraction, generalization and classification than many other programming techniques. Some tools of object oriented design and programming are encapsulation, classes, inheritance, modularity and reusability. Expert systems have been used for years to implement process control strategies in the minerals industry. Expert systems allow process control knowledge to be expressed in linguistic rules that are processed by an inference engine. Expert systems which employ object oriented design and programming provide new opportunities for real- time process control. The concepts of object oriented programming and an example object oriented expert system are discussed in this paper.

Jan 1, 1992

By Y. A. Attia, D. K. Sengupta, H. A. Hamza

Increased recycling of waste paper has been emphasized in recent years in both the United States and Canada for environmental and economic reasons. Removal of ink particles from waste paper pulp is therefore necessary. One of the most promising methods for ink removal is froth flotation. This study investigated the feasibility of a simplified flotation scheme and found that about 90% to 92% ink removal can be achieved. Also, a 95% to 97% ink removal is achievable if a hydrophobic polymer is used ahead of the flotation stage. Clean paper pulp recovery was over 90%. The effects of pulping pH, flotation pH and concentrations of flotation and polymeric reagents are discussed in the paper.

Jan 1, 1995

By Michael F. Jeglic

Dust control methods are practiced throughout the mining industry in order to protect the health and safety of its workers, the integrity of the environment, and to guard against the loss of valuable product. The use of water is often the best and most economical method of controlling dust. Increasingly, chemical agents are being chosen over more traditional mechanical means of controlling dust. Some chemicals are used alone, and many are used to enhance the dust controlling properties of water. This paper describes the various types of chemicals available and their applicability to specific problems encountered by industry.

Jan 1, 1986

By John A. Herbst

At the last Comminution Symposium a challenge (Meloy and Williams, 1992) was issued to "predict the typical straight-line, self similar" tumbling mill product size distributions using a population balance model (PBM). Implicit in this challenge is the assumption that the PBM is inadequate for predicting real world grinding performance. This response is presented in three parts: I. Theoretical analysis of the general PBM and its appropriateness for comminution system modeling. II. Examination of the accuracy of prediction of real world milling behavior using linear and nonlinear PBMs. III. Evidence from recent microscale comminution research. This paper concludes with recommendations concerning future research which will: 1. further elucidate mechanisms of particle destruction and creation as well as attrition and 2. increase the accuracy of model predictions in highly nonlinear situations

Jan 1, 1997

By D. Ince

Flotation of dolomite from apatite was investigated, using dodecylamine hydrochloride or sodium oleate as the collector, with and without inorganic modifiers such as sodium chloride. Separation of dolomite from apatite was anticipated from the single mineral experiments under various pH and collector concentration conditions. Flotation selectivity in the mixtures, however, was found to be limited. Attempts to control the flotation response of these minerals by addition of salts such as NaCl and KCI indicated that selectivity is possible. The presence of sodium chloride was determined to depress apatite flotation using sodium oleate, leaving dolomite flotation unaffected (Moudgil and Ince, 1989). In this paper, conditions for optimum separation and the effect of major parameters on the desired selectivity are discussed.

Jan 1, 1992

By P. J. Ryan

December 1988, Phelps Dodge Corp. brought an underground gold mine into production in the republic of Botswana. The mineralization is associated with steeply dipping shear zones in Archean greenstones of the Tati schist belt. The gold is intimately associated with sulfides and is refractory in nature. The deposit is being exploited by underhand open stoping methods. Vertical and inclined shafts are used to hoist the ore to the surface where it is treated by conventional crushing, milling, and flotation, followed by fluid bed roasting with cip elution and carbon regeneration. Adjacent deposits are being explored with a view to increasing production. Legal and taxation aspects of operating in Botswana are discussed.

Jan 1, 1991

By M. Prasad, G. M. Rao, A. K. Majumder, T. C. Rao

Froth flotation was employed to beneficiate a lean-grade siliceous rock-phosphate ore containing fluorapatite, the phosphate-bearing mineral. The main gangue minerals were quartz, iron oxides and aluminum oxides. After the rougher stage, four cleaning stages were required to upgrade the ore. The liberation size of the phosphate mineral was below 200 mesh, The reagent scheme consisted of commercial-grade sodium silicate and sodium oleate. The effect of reagent dosages, number of cleaning stages and pulp density on the efficiences of separation were studied systematically. A flowsheet was proposed for the processing of low-grade siliceous phosphate ore containing 12.1% P2O5, 55.36% SiO2 and 15.45% CaO. The flowsheet provided a useable phosphate concentrate containing 34.18% P2O5 and 14.20% SiO2 with a P2O5 recovery of 70.4% (the weight yield was 25.0%).

Jan 1, 1999

By J. P. Savely

This paper describes the development of a trim blast design to improve the stability of a final pit wall. Description is given of the effects of rock characteristics, rock type, and pit plans on the blast design. Currently, six benches have been mined with trim blasting. A more stable final wall has resulted and the successful program has reduced mining costs over an extended time period. Low-cost blast monitoring and field observation were used to determine peak particle velocity and blast damage. Using criteria developed from this relationship, trim blasts were designed and evaluated.

Jan 1, 1987

By J. Partyka, J. S. Stachulak

Dust produced during blasting in a copper/nickel based mine was studied and characterized. A stope utilizing the crater blasting technique, or the vertical retreat mining (VRM method), was examined. Two dust monitors were used to measure an airborne dust produced during blasting operations. The data collected in situ was primarily used to formulate the boundary value problem for a generalized equation that describes the transportation process of airborne dust from all places where dust is produced by the VRM mining method. The field data was also used to define the analytical forms for the initial and boundary conditions, to provide a simple and reliable equation for flow of dust in a stope vicinity, and to identify the non-measurable constants. The effects of the amount of blasting material and of the ventilation system in use on dust concentration are also discussed.

Jan 1, 1995

By W. D. Diment

The concept of flying employees in and out of remote mine sites on a regular rotation basis, rather than establishing permanent support communities nearby, has gained increasing acceptance by mine operators, unions and regulatory agencies in Canada. The development of successful fly in/fly out programs and resultant compressed work schedules is dependent on meeting design requirements through comprehensive research of worker profiles to ensure the selection of suitable employees and the implementation of satisfactory working conditions. This paper presents an overview of Canadian mine industry practice with regard to the fly in/fly out mode of operation and compressed work schedules.

Jan 1, 1987

By J. A. Organiscak

This paper examines methods for limiting occupational silica exposures for roof-bolting personnel in underground coal mining. A canopy air curtain and an air tube were evaluated as means to provide filtered air over the breathing zone of these personnel. Laboratory testing showed that dust reductions beneath the air curtain and air tube approached 60% and 40%, respectively, with low interference air velocities. The data also showed that dust reductions were highest for positions closest to the device and that these levels decreased with distance. This paper also evaluates a metal rake, a flexible insert and a rigid insert for cleaning the roof-bolter dust collector box. Less dust was produced when using the rigid insert. Surprisingly, the flexible insert was sometimes no better than scraping or raking the dust onto the mine floor. However, little dust got on the workers coveralls when using either of the inserts.

Jan 1, 2003

By Bern Klein, Richard W. Lawrence, Scott Frostad

A laboratory study was conducted to evaluate the effects of various kinetic test protocols on sulfate production, NP depletion and time to acidity. Six test protocols were evaluated including standard humidity cells, non-aerated cells, tall cells, shaken cells, simulated precipitation cells, and NP depletion columns. The study indicates that test protocols which disrupt the oxidizing environment, such as extreme wetting and drying cycles, shaking the cells, or the high addition of acidic water will create an unnatural environment that affect the results. Trickle leach and non-aerated test protocols create an oxidizing environment that more closely represents field conditions and are therefore recommended.

Jan 1, 2000

By Oscar Letelier Gonzalez

The goal of mine planning is to determine "the best" strategy to exploit an ore deposit during its workable life. Such strategy must be consistent with the objectives of the company and must be subject to the contraints imposed by economical, physical and geological conditions. Mine planning process may be broken down into three categories, according to the planning horizon: Long range, Short range and Operational. The shorter the scope of planning, the higher the level of details and the lower the degree of freedom associated to each plan. A long range plan defines the economic limit of mining at the mining life end of the deposit; it also can be used as an aid in the evaluation of the economical potential of a mineral deposit and as a guide for short range plans.

Jan 1, 1979

By Justus B. Deen

Given that the majority of mine ventilation operating costs are imposed by shafts, the need to predict the resistance of a planned shaft with reasonable accuracy is important. During conceptual design, shaft resistances are usually predicted by use of published friction factors, k, based upon lining and fitting configurations. More often than not, published friction factors do not directly coincide with "real" shafts, so their use is somewhat limited. For more accurate shaft resistance determination, equations both theoretical and empirical may be employed if there is detailed knowledge of the shaft. These equations treat the shaft resistance as discrete components, with their sum being the overall shaft resistance. This paper describes the basic shaft resistance equations and verifies these equations by comparison to field measured shaft resistances. Several shafts were examined which varied in depth, shape and fitting arrangements. Results are presented and conclusions drawn to show that the shaft resistance equations are accurate.

Jan 1, 1991