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By C. J. Konya, A. Konya

"Presplitting is a form of blasting that when executed properly will create a smooth wall that will minimize secondary conditioning. In recent years, presplitting has become a popular technique to be used in both the mining and construction industry, however, presplitting fails on many occasions because of ‘geologic conditions’. This is typically because of improper explosive loads consisting of overloading and underloading blastholes. In this paper the authors introduce new factors such as a presplit factor which varies for different rock types, selection criteria for the spacing of presplits, the optimization of explosive load, as well as prediction methods for the environmental affects for the technique of Precision Presplitting. BACKGROUND Methods of controlled blasting in which a smooth, stable wall could be blasted have been an important consideration since blasting in mining and construction has begun. How can one use an explosive, with its massive energy and power, to break a non-homogenous rock without causing backbreak, poor walls, or deviations in the wall over large distances? The blasting industry has known for a long time that blasting ‘high benches’ would result in better walls and less backbreak. However, this was not a sufficiently controlled technique for critical projects, such as the Niagara Power Plant. This was one of the main challenges Hercules Powder faced when they began the project. In order to achieve this, they used a new tool in the explosive engineer’s toolkit, presplitting. The presplitting done on the Niagara Power Project utilized 1 ½” x 8” (38mm x 203mm) 40% gelatin dynamite in 2 ½” (63.5) diameter boreholes. This was done on multiple levels with benches between 12 feet to 52 feet (3.6m to 15.8m) with a total powder factor of 0.75 pounds/cubic yard (0.45 kg/m3). The spacing on these holes ranged between 18 inches to 24 inches (0.46m to 0.61m), center to center (Langfors & Kihlstrom, 1973). The strange aspect of this project was that this “lightly loaded” closely spaced row was fired before the production blast, yet this project produced some of the best walls seen at that time directly from blasting. In today’s blasting industry, presplitting is a more common way to produce smooth, stable high-walls for both the construction and the mining industry. Today, explosive loads for traditional presplitting is generally measured in pounds per foot (kilograms per meter) and typically ranges from 0.30 lb. /ft. to 0.5 lb. /ft. (0.45 kg/m to 0.75 kg/m). MECHANICS OF PRESPLITTING When analyzing a blasting process like the Niagara Project, many wonder how did that work when normally confining a charge would cause cratering and increased backbreak. Since then, presplitting mechanics have been studied extensively. It has been shown in many models that presplitting is not achieve through the collision of shockwave, but by gas pressure in the boreholes. In addition to models and finite element simulations, this has been proven full scale using Pyrodex, a propellant, to create a presplit plane with no shock wave present (Konya, Dean Barrett, & Smith Jr, Presplitting Granite Using Pyrodex, A Propellant, 1986)."

Jan 1, 2017

By R. R. Guzman

In this study, the "Mine Project Risk Management" methodology, MPRM (Botin et al. 2011), has been applied to characterize the sources of uncertainty and to quantify risk in the mining engineering stages of Block Caving mining method. As the result, rock mass caveability and ore fragmentation were identified as the two most relevant parameters of this process and a methodological model has been developed to quantify the risk associated to each of these two parameters. Furthermore, the applicability of the proposed model has been validated using as a case study the Chuquicamata Underground Mine Project in Chile.

Feb 23, 2014

By F. H. Mertens

The costs of an open-pit operation can be classified according to the following hierarchy : -overall cost of production (per ton of ore) -costs of basic operations and functions -costs of auxiliary operations -costs of machines and equipment -maintenance costs. Production cost is a measure of the open-pit mine performance and should be the final target of the management control. It is also a measure of the share of the mine in the processing stages.

Jan 1, 1990

By A. E. J. Gallagher

There are many influences which have a bearing on the economics of industrial minerals production. The purpose of this paper is to discuss briefly three factors which have economic significance in the production of these mineral commodities. The three items of discussion include 1) the nature and relative value of the industrial minerals group, 2) project planning, and 3) market analyses. General aspects of these factors are familiar to most of us. However, an attempt will be made to give some current details regarding each. Also, in reality, project planning and market studies are usually so closely associated that they will be discussed jointly, rather than separately. This will be done by way of examples which show how these two activities actually evolved for two industrial minerals projects.

Jan 1, 1984

By J. T. Crawford

The purpose of this paper is two fold. It will: (1) examine leasing analysis as a project evaluation criterion, and (2) compare the cost of leasing with other methods of financing. The use of leasing has grown extensively in recent years as a method of obtaining equipment. The computer industry has been highly dependent upon leasing from its earliest days to dispurse its equipment to the customer, while airlines and railroads acquire large segments of their aircraft and rolling stock by leasing. Over the last few years the mining industry has leased haulage trucks, bulldozers and other equipment of similar nature.

Jan 1, 1974

A case study of a systematic approach to grinding circuit steady-state optimization is presented. After overall review of the flowsheet, two circuits were prepared for detailed testing. Functional performance analysis was chosen as the primary modelling system, and on this basis a quality assurance program for data gathering was implemented. A number of circuit design and operating variables were experimented with statistical analysis of plant test results revealed relationships previously unquantifiable by any other modelling technique. Improvements in classification system and mill grinding efficiencies were demonstrated and significant energy cost savings thus realized.

Jan 1, 1998

By J. C. Cawley, G. T. Homce

The U.S. National Institute for Occupational Safety and Health (NIOSH) Office of Mine Safety and Health Research (OMSHR) conducted a study of mining industry electrical injuries reported to the U.S. Mine Safety and Health Administration (MSHA) for the years 2000 to 2009. The findings of that study are detailed in this paper, and serve to characterize the circumstances surrounding electrical injuries and identify causal factors. The study included three tasks: 1) a direct review of mining industry occupational injury data compiled by MSHA, 2) interpretation of the narrative descriptions available for the injuries (from MSHA data) and 3) a separate examination of fatal electrical injuries. Eight-hundred sixty-five electrical injuries were reported during the 10-year period studied, with 39 of those being fatalities. This makes electrical injuries disproportionately fatal with respect to most other types of injuries in mining. Electrical injury rates were higher in coal mining than noncoal mining and, within the coal sector, rates were higher in underground operations than in surface operations. Of the 865 total cases, electrical and machine maintenance or repair activities were involved in 580 (69%), and electricians and mechanics were injured in 362 cases (42%). Of the 39 fatal electrical injuries, 27 (69%) involved electrical maintenance or repair work, and in 21 of these 27 cases, the failure to de-energize, lock-out and tag the circuit was the cause or a contributing factor. Also, contractor employees had a much greater chance of an electrical injury being fatal than did mine operator employees. The top three root causes for fatal electrical injuries were 1) no or inadequate lock-out and tagging, 2) failure of power system components and 3) contact of overhead electrical power lines by mobile equipment.

Jan 1, 2013

By Rodolfo V. de la Cruz

Abstract. The Hoskold mineral valuation method was critically examined. The original derivation was presented and found to contain a number cf erroneous assumptions as follows: the sinking fund must be available for reinvestment in another property; the series of reinvestment of the sinking fund results in a perpetual annuity to the investor, and; evaluation of the present value of the net cash flows at the speculative rate of interest. The proper procedure of deriving the Hoskhold mineral valuation formula was discussed and illustrated with a cumulative cash position diagram, a useful tool in economic evaluation and investment decision methods.

Jan 1, 1980

By Sunny Schoone, Maximilian Getz, Felix Leaman, ELISABETH CLAUSEN

Jan 5, 2023

By Baolin Qu, Jingxin Wang, Cuncang Xu, Bing Wu, Mingyu Zhong

With the development of the coal mine regulation regime, the situation of coal mine safety production in China has continued to improve. However, coal mine accidents have not been fundamentally eliminated; constantly learning from historical accidents can make mining work safer. Therefore, to better understand the coal mine accident characteristics, this study analyzes the tendency of coal mine safety accidents from multiple perspectives, among which all accidents after the establishment of the State Administration of Coal Mine Safety in 1999 are the top priority. The results show that strict national policy, technological progress, and reasonable coal prices are conducive to the safe development of mines. On the contrary, high-intensity centralized production will lead to frequent accidents in the peak season of coal production. In addition, the type of coal mine ownership will have an indirect impact on the occurrence of coal mine accidents. The research results not only play a positive role in the prevention and control of coal mine accidents in China but also have reference meanings for the safety production of coal mines in other countries in the world.

Dec 28, 2022

By Larissa Koroznikova, Steve Durkin, Bradley Drake, Michael Tuck

This paper presents the results from the investigation of the application of thermal fragmentation in Australian hard rock underground narrow-vein mining. Two geologically similar samples from an underground narrow-vein hard rock gold mine were collected to obtain a measure of the technology’s ability to recover ore by the creation of large thermal openings to assess the applicability of the thermal method. Particle size distribution showed a higher generation of fine product, − 2 mm, by thermal fragmentation compared with selective blasting by 31%. The Bond work index for thermal ore (12.62 kWh/t) is half to that of the blasted ore value (25.32 kWh/t). The average grindability obtained for the thermal ore sample was greater than the blasted sample by a factor of 2.44, a higher value indicating a decrease in the energy required to grind. The thermal fragmentation method generates product with higher dissolution of gold in cyanide, by 14% for the − 9.5 + 2 mm size fraction samples. Additionally, the thermal fragmentation results in higher production of − 9.5 + 2 mm material by 15 % compared with selective blasting.

By Louis D. Murino

Compared to coal or many metals industries, talc must be considered a small, specialty market catering to niches and dependent primarily on the physical attributes of the mined and processed mineral rather than the chemical attributes with copper, lead or uranium concentrate, the primary objective is the percent metal that ultimately is refined by the smelter, as opposed to the brightness, particle size distribution, trace impurities or morphology. The latter constitute the important determinants of where, how and why talc and similar industrial minerals are used. This paper addresses the talc market-place: where it is, how much of a market there is, who the producers are, available capacity, market growth, and marketing techniques.

Jan 1, 1984

By Dwight R. Coles

The solving of complex metallurgical flowsheet calculations by hand is, at best, a tedious job which often proves that engineers, too, make mistakes. The high cost and long lead time associated with manual flowsheet solutions have led several organizations involved in research, development and construction of extractive metallurgical processes to search for computerized systems which will solve flowsheet calculations. Although design flowsheet programs have been developed by the chemical industry, the ability to solve flowsheets involving particulate solids is usually overlooked. A new computer applications system has been developed at Fluor Mining and Metals which has been designed to accommodate the type of design flowsheets required by the minerals industry. By employing the sequential modular computation technique, a library of metallurgical pro- cessing routines may' be accumulated which are used by a universal executive system. This technique enables rapid solution of new process) .flow- sheets with only a minimum of additional programming effort. The implementation of the FLEXMET flowsheet solution system is the subject of this paper. Some of the major features of the system which are examined include interactive input data handling, automated flowsheet calculation order arrangement, flexible accomodation of unit operations models and advanced management of recycle and specification control calculations.

Jan 1, 1982

By M. Rezaee

Push backs used in the production planning of open pit mines play an integral role in generating annual cash flow. Although several algorithms for push back designs have been proposed, none have studied the optimum number of push backs. In this paper, different algorithms have been implemented for the push back design of a cross section of a copper deposit and the results discussed. Moreover, the optimum number of push backs has been determined using analytical and multiple attribute decision making (MADM) methods based on minimizing the risk associated with grade uncertainty, and minimizing stripping ratio, while maximizing net present value (NPV). According to the findings, the optimum number of push backs has been proposed to be between three and six, as lower quantities of push backs are more likely to achieve the calculated net present value, and have smoother stripping ratios for different pushbacks. This approach was examined in an operating mine and the optimum number of push backs determined to be four.

Jan 1, 2012

By Bill Elverman

Randy and Kenny Robison have visited every coal mine that would let them in the door, to survey the best mining practices. The brothers have spent nearly their entire lives working in coal operations. The Robison’s started out on lube and grease trucks and worked their way up to respected industry leaders in Alabama. The Robisons have owned MS&R since 1989. Since then, they have created a niche for themselves in providing coal for Alabama’s metallurgical coal market. A great deal of the knowledge the Robisons have amassed throughout the years has come from observing — taking note of what works and what does not. In early spring 2004, they commissioned a Komatsu America PC3000 Super Shovel. Outfitted with a backhoe attachment and a 16-m3 (21-cu yd) bucket, MS&R’s PC3000 is currently one of the largest mining excavators working in Alabama.

Jan 1, 2005

By Neall. George M.

No method of roof control yet devised has proven to be universally acceptable for the wide range of strata conditions experienced in U.S. coal mines. However, a relatively new innovation, the roof truss, has proven itself capable of preventing roof failures which both conventional and resin bolting could not. Presently, the economics of roof trusses are not favorable when compared to bolting due primarily to drilling and installation procedures, but this is expected to change with improved truss and equipment designs. To realize the full potential of this new method of roof control, design criteria are needed which can optimize the effect of the truss for varying strata conditions. A review of the literature reveals that some work has been conducted on the roof truss. 1 Gambrell and Haynes (1970) showed that the roof truss is superior to angled roofbolts installed through a header. Sheorey, Verma, and singh2 (1973) used statics to prove that the optimum angle of inclination should be greater than 450? However, to date, no systematic attempt has been made to establish design criteria. In this report, the problem was approached in three ways. First, model studies were performed to determine general trends of truss support as a function of a number of variables. This provided a better understanding of the support mechanism involved. Secondly, beam theory was employed to calculate the actual support capacity of a truss, realizing the many simplifications, assumptions, and shortcomings of this approach to such a complicated problem. Last, field testing will be utilized to test the hypotheses previously developed and provide hard data to further synthesize roof truss design criteria. Field testing has recently commenced and should be complete before mid 1977.

Jan 1, 1977

The implementation of NAFTA in January of 1994 was expected to have small but beneficial effects for the Mexican economy, mostly through increased investment flows. Mexico's mining industry was especially likely to benefit, as mineral investment funds would be diverted to the now safer Mexico and away from similarly endowed but more risky Latin American mineral economies. The results of the past two years have shown that it is governments and macroeconomic factors that influence investment flows, rather than the fine-tuning of trade flows through so called "free-trade" agreements.

Jan 1, 1996

By Carl G. Hogberg

To the casual observer there is probably no simpler appearing operation in the mineral industry than a limestone quarry. It might seem that the entire operation - from the drilling, blasting, and loading of the stone, its transport to a mill for crushing, washing and sizing, to loading into boats, railroad cars, or trucks for delivery to customers - can be comprehended at a glance. But no first impression could be more misleading. It is one of the purposes of this presentation to sketch the broad outlines of the extensive limestone industry in the United States which, measured in terms of volume of production since the end of World War II, has grown almost 300 per cent to a national level in 1957 of 384 million net tons.1 Another objective will be to discuss in more detail this industry in the State of Michigan. For this latter purpose, the Michigan Limestone Division plants at Calcite and at Cedarville will be used as examples. These descriptions will, we believe, show that the limestone business has complexities to match its size.

Jan 1, 1962

By J. Pang, S. Chander

The mechanisms of chalcopyrite oxidation in alkaline solutions have been studied using cyclic voltammetry and impedance spectroscopy techniques. The cyclic voltammetry was used to elucidate oxidation/reduction reactions, whereas impedance spectroscopy was used for in-situ characterization of the interface. To analyze the impedance spectra, equivalent circuit models were constructed based on a layer- wise growth of reaction products. Parameters of the equivalent circuit were calculated by comparing the experimental spectrum with that expected on the basis of equivalent circuit. From the value of equivalent circuit parameters, properties of the surface layers were inferred. These properties change substantially with the change in oxygen and/or collector concentration in solution. From such changes the effect of oxygen and collector concentration on the contact angle and flotation behavior of chalcopyrite were interpreted.

Jan 1, 1991

By Alireza Kamrani, Yashar Pourrahimian, Hooman Askari-Nasab

In-pit crushing and conveying (IPCC) is an option to decrease the enormous operating costs that a truck shovel can introduce in an open-pit mine. Finding the best locations for the IPCC over the mine life will impose a new set of requirements for the mine planning. Through a two-step mathematical programming model alongside the road network, this method finds the optimal in-pit crusher locations and relocation times first and then optimizes the long-term mine schedule. The model is verified by a real mine. The results show that the truck travel time could be reduced by 500% and the discounted cash flow increased by 8% with an optimized schedule considering the crusher placement.

Jun 25, 2023