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By G. L. Mowrey

A new coal interface detection (CID) method is under investigation by the U.S. Bureau of Mines. This novel concept is based on utilizing a passive infrared system (FIR) to measure temperature changes associated with the cutting of coal and adjacent strata. For this method to work successfully, a definite mechanical/hardness contrast must exist between coal and rock. Advantages include that FIR responds instantaneously at the coal-rock interface and it is minimally affected by dust and/or water sprays. Based on preliminary tests, results indicate that the PIR method can be applied successfully in mines having a hard immediate roof.

Jan 1, 1990

By R. A. Thomas, C. D. Litton

"The objective of this study was to develop a laboratory-scale method to rank the ignition and fire hazards of commonly used underground mine materials and to eliminate the need for expensive large-scale tests that are currently being used. A radiant panel apparatus was used to determine the relevant thermal characteristics of the materials: time to ignition, critical heat flux for ignition, heat of gasification, and mass loss rate. Three thermal parameters, TRP, TP1, and TP4, were derived from the data, then were developed and subsequently used to rank the combined ignition and fire hazards of the combustible materials from low hazard to high hazard. The results compared favorably with thermal and ignition hazards of similar materials reported in the literature and represent a simpler approach to quantifying these combustible hazards. INTRODUCTION The potential fire hazard from combustible mine materials is a major concern that can impact the safety of mine workers. Combustible materials tend to be solids and within this category there exist degrees of flammability and fire resistance. These materials may be readily ignitable or they may be able to withstand high temperatures and high heat fluxes. Presently, no simple methodology exists to assess these possible fire behaviors and quantify the resultant fire hazards. Thus, better knowledge of the thermal properties and chemical characteristics of combustible materials is of great importance to the safety of mine workers. Tewarson [1994] developed a methodology which he subsequently used to evaluate the ignition and fire resistant properties of combustible mine materials, but these efforts are more than 20 years old, and do not include many of the new materials used in mines today. The standard practice that has evolved for a combustible material to be approved by the Mine Safety and Health Administration for use in underground coal mines is to conduct extensive and costly large-scale experiments on each new material that is used in a particular mine operation. Results of such tests provide pass/fail answers to the questions of a material’s flammability or fire resistance, yet they provide little, if any, information that will lead to a better understanding of the basic mechanisms involved. Therefore, there is a need to quantify material flammability properties and to develop a methodology to rank the ignition and fire hazards of commonly used underground mine materials. During the heating and ignition stages of combustible materials, properties such as smolder susceptibility, minimum surface temperature for ignition, thermal conductivity, heat capacity, density, and heat of gasification are known to be important [Apte, 2006]. During the flaming stage, additional parameters, such as the heat of combustion, heat release rate, flame spread rate, yields of soot/smoke, and toxic gas production become more important as the flame is sustained and spreads. In very general terms, the heat flux incident on the surface of a solid combustible not only controls the rate of temperature increase of the local fuel surfaces, resulting in expulsion of fuel vapors that sustain the flaming process, but also the heating of other combustible surfaces that subsequently ignite and spread flame."

Jan 1, 2015

By V. P. Mehrotra

The effect of dissolved ions present in plant water on the flotation of phosphate ore from central Florida was investigated. Of the three most abundant ions, namely Ca++, Mg++ and SO4--, calcium ions were the most detrimental in the flotation of phosphate with sodium oleate collector. In one feed, a 10 ppm concentration of Ca++ ions reduced the BPL recovery from 86% to 46% whereas in the other a 40 ppm concentration lowered the recovery from 90% to 52%. The effect of Na2C03, NaHC03, Zeolite and EDTA to remove ca++ ions from water and hence improve apatite flotation was also studied.

Jan 1, 1986

By Ebrahim Tarshizi, Livernois Ryan, Emily Sarver, Zoe Scopa, Robert Setterlind, Leah Frost

"The mines of the future present a host of challenges, which may appear exciting or daunting, depending on one’s perspective. Whether some sectors of the public recognize it or not, the demand for raw resources is not going away any time soon. In fact, it is rising, as the global population grows, urbanizes and attempts to steadily increase quality of life. Yet, at the same time that much of the highly developed world is calling for greener goods, reduced consumption and cleaner production, in other areas there are cries for clean water and sanitation, consistent energy supply, access to health care and education, personal security and support for basic human rights. The balancing act for sustainable development of our global society is, indeed, precarious and the mining community is a key player. Fortunately, many industry members have accepted this role and the responsibility to provide leadership and a solid foundation for progress. Looking ahead, we need new generations of leaders, including many mine engineers who are ready to tackle all sorts of complex problems.There are tremendous needs just for technological innovations. Increasingly tough deposits will require that the industry continues to expand scale toward “mega pits” and “super caves;” fully develop unconventional recovery techniques like in situ leaching and gasification or deep-sea extraction and seriously consider off-earth endeavors. Such work will take entirely autonomous equipment, novel separations, processing and recycling methods, and systems that can withstand extreme physical conditions, just to name a few. It will also take a level of systems integration never-before seen in the mining industry, complete with big data issues, sophisticated predecitve analytics and modeling efforts and cyber-security challenges.Moreover, increasingly complex environmental problems will require creative solutions. Addressing issues like pollution control across multiple media, emerging contaminants, optimal management of wastes, selective mining and shared use of resources between mine operations and surrounding communities and ecosystems are among the top priorities. Really, a complete paradigm shift must occur, such that the focus is on overall improvement of environmental conditions, rather than minimization of impacts. A similar shift will be required in the social realm. How can miners be safer and healthier on-site and off? How can the industry contribute to communities such that they are better off, now and longterm, for having a mine next door? How can artisanal mining practices be transformed to also contribute to sustainable development? How can the industry’s work be a factor in increasing economic and political stability? How can the public understanding of raw resources and the need for mining enterprises be improved?Given the coming challenges, there is no doubt that the mine engineers of the future will need highly diverse skillsets — meshing traditional and contemporary competencies to a degree not previously considered in mining, or most others fields. To be sure, the scope and scale of mining projects make them wholly different than most other engineering work, aside from perhaps the largest civil and urban development projects. While on-the-job experience will continue to be essential, formal education programs (i.e., at post-secondary institutions) must lay critical groundwork."

Jan 6, 2017

By Elena Chiriotti, Federico Valdemarin, Jan Cenek

"SUMMARY The “28 May Station” is the only transfer station between the existing Green and Red metro lines in Baku. As part of the huge development strategy of the metro network, the complete separation of the existing underground lines has been planned at this location, in order to simplify the operation of the future metro system. The extreme challenge of the project is represented by the need of achieve the separation of such lines over a breakdown of the operation of just five weeks. The lack of direct access from the surface, a complex geology with artesian water layers, a congested underground space and sensible buildings represent additional constraints. The chosen design solution consists in creating a complex steel pipe jacking frame around the operating tunnels and then excavating under such frame two large caverns where the separation of the existing lines and the construction of the new metro tunnels will be achieved. Soil treatments have been conceived to mitigate the geotechnical risks and to reduce possible impacts on the existing structures. The paper illustrate the challenges of this extraordinary project, one of the most complex underground structures under study, the design solutions and the risk management approach used to manage the complexity and to design the mitigations measures. INTRODUCTION The metro network in the capital of Azerbaijan is rapidly growing together with its metropolitan area. The beginnings of the existing metro system started in Baku in 1967 in Soviet times. To date, only two lines (Green and Red) are in operation with a total length of 34 km, including 23 stations. The future network will be much wider: besides the construction of three completely new lines and the extension of two existing lines, the whole metro project includes the development and modernization of the existing metro sections. A consortium formed by Systra (leader), Mott MacDonald (Praha) and Saman (Korea) awarded the contract for the preliminary and detailed design of infrastructures for the extension of Baku Metro Network. This extension consists in 83 km of new lines and extension of existing lines. As part of this modernization project, the connection of the Green Line at the 28 May / Cefer Cabbarli Stations, focus of this paper, represent also it’s ""Achilles' heel"" given that the already very congested system have only one transfer station."

Jan 1, 2016

By James A. Jessop

The Bureau of Mines is investigating the use of geophysical methods to determine rock mass characteristics, particularly rock quality, lithology, and fracture parameters that are important for determining the feasibility of in situ leaching operations. As part of this research, two Bureau-developed crosshole geophysical systems are described that can be used for site investigation and rock mass characterization. Results are given for performance tests at field sites in Arizona and Texas and for correlations between the crosshole seismic data with fracture frequency, rock quality, and lithologic variation. Recommendations are made for using elastic waveform propagation characteristics and dynamic elastic properties for improving rock mass characterization in the geomechanical assessment of in situ leaching deposits.

Jan 1, 1990

By S. G. Britton

Microcomputer analysis has long been a technique for engineering professionals to improve the theoretical and practical design of continuous mining systems. Such work has been typically composed of modeling observed events and then introducing a variety of known elements with predicted results to compare against the results of the model. Programs written in BASIC, Cobol, Fortran, or other language dominated such efforts. These programs have taken years to develop and prove out. This paper explores a new management tool used at TMC on a daily basis to track and improve continuous mining systems through the use of microcomputers and Lotus 1-2-3 software. By analyzing data provided by section foreman, shift foreman, and maintenance personnel against predetermined goals, new production targets are developed, weaknesses in the current mining systems are identified, and the results of changes are measured. The results of this system on the productive output of TMC systems are on the order of ten percent improvement.

Jan 1, 1991

By W. D. Eddy

Topaz is a fluorine-bearing aluminosilicate mineral of the kyanite-sillimanite group. The formula has been given as Al2SiO4(F,OH)2, [Al(F, OH)]2SiO4, or 2Al2O3?2Al(F, OH)3SiO2. Topaz is generally considered a semiprecious-to-precious gem mineral, but it is a fairly common minor constituent of granites. In 1937 the U.s. Geological Survey reported an occurrence of massive topaz in the 3 Brewer gold mine, Chesterfield County, S.C. Over the next 8 years considerable research was done on topaz to establish its properties and to determine possible end uses The first reported shipment of ore was in 1939 Peak production was reached in 194412, and output then began declining until the mine closed in 194913? During World War II topaz was used in refractories, as a flux in steel mills, and in the manufacture of borosilicate glass 14. The main advantage of using topaz over kyanite and sillimanite in refractory use was that calcined topaz converted to over 95 percent mullite (3A1203 .2Si02) while calcined kyanite or sillimanite contained only 88 percent mullite15. However, a major draw-back to utilization of topaz is the evolution of fluorides during calcination. In 1973 the Geological Survey reported that topaz occurred in probable commercial quantities in at least two domestic locationsl6: the Brewer area of South Carolina and a location in Colorado. The literature also indicated that progress had been made in controlling fluorine-bearing fumes. This research has progressed to the state where valuable fluorine compounds are being recovered on a commercial scale 17. Thus, a major obstacle to utilization of topaz appears to have been resolved. The Bureau of Mines under its program of advancing minerals technology initiated a project to study techniques for the concentration of topaz from disseminated materials. The objective of the study was to determine those techniques that would be used to produce topaz concentrates that could be utilized as a source of fluorine and mullite.

Jan 1, 1977

By S. Tuylu, D. Adiguzel, A. Bascetin, O. Ozdemir, U. Cinar

"In recent years, use of mineral processing tailings as a paste backfill has been significantly increased due to the environmental problems occurred during the disposal of the tailings in mine area. The paste material used to fill the stopes excavated is generally consisted of tailings (solid ratio: 70–85%) and cement (3-7%w/w). Meanwhile, the strength of the paste material is completely related to ratios of these materials. Cemented Paste Backfill (CPB) system is used as support depending on the roof pressure and also as an underground disposal method. Therefore, temporary strength value of the paste material gains a great importance. For example, the paste backfill material must compensate the minimum 4 MPa strength value in order to procure the permanent fortification, and the mixture cost must be minimal as well. For this reason, in this study, the Pb-Zn tailings were used to prepare for the paste backfill material using cement in order to perform the uniaxial compressive strength (UCS) tests. Additionally, a statistical experimental design and linear programming techniques was used to find the optimum mixture in terms of strength and cost. The pulp solid ratios (PSR) of the tailings and cement (by the solid) were varied as 75-85% and 3-8%, respectively. The results of this study; the optimum mixture is ~79.5%PSR and 6.8% cement ratio (by the solid) for 4 MPa UCS (28 day) and 16-17 cm slump value determined by this method with statistically reviewed experimental data. INTRODUCTION Fine-grained tailing waste materials resulting from mining activities are an important environmental problem. In terms of environmental protection, the use of tailings with paste backfill is a very attractive approach and a desirable solution to tailings management. Paste backfill, which is used to fill underground openings, is made by primarly mine tailings mixed with hydraulic binders and water. Its main benefits are not only disposal of mine tailings in underground, but also providing a certain strength to ensure a safe working environment. Therefore, it is necessary to use hydraulic binders due to durability of the system (Benzaazoua et al., 2004). Paste backfill, formed from the mix of dewatered plant tailings (75-85 wt. % solids), water and binder (3-8 wt. %) (Brackebusch, 1994; Landriault et al., 2005).Water is used to determine the chemical reactions between tailing and binder materials for strength as well as increasing pumpability. Portland cement and ash can be used as binder materials (Douglas and Malhotra, 1987). The factors which affect strength and stability of paste backfill separate into two groups called interior and exterior factors. Interior and exterior factors determine the strength, stability and deformation features of backfill in short and long terms and also affect the transportation of backfill to underground (Benzaazoua et al., 2004; Erçikdi et al., 2006; Yilmaz et al., 2010; Nasir and Fall, 2010). Material properties of tailings as well as site operations to fill the underground openings are the most important steps for the design purposes. Grain size distribution, chemical, and physical properties of tailings, and mechanical properties of paste fill material are used to understand the suitability of tailings as paste fill material (Ozturk et al., 2014). In addition, Fig. 1. is also proposed to apply a typical design for the operational stages of paste fill applications on the site."

Jan 1, 2016

By A. D. MacPhail

The Highland Valley Copper partnership was formed in July 1986 and was the logical result of a mine with a large ore reserve but no adequate mill, and a mine with a large, modem mill but dwindling ore reserves. The original partners -Cominco and Lornex -were joined in January 1988 by Highmont Mining Co. which contributed a two-line concentrator. During 1988/1989, the Highmont mill was moved 7.5 km to adjoin the Lornex mill, forming what is now called the Highland mill, with a current nominal capacity of 130 000 tonnes per day. The mine is located 220 km northeast of Vancouver, British Columbia and is close to four communities in which personnel make their home: Logan Lake, Merritt, Ashcroft, and Kamloops. The map in Figure 1 2.2 shows the general area. Kamloops is a major service centre and is serviced by two railways, two major roads and a regional airport.

Jan 1, 1993

By R. Casagrande, L. R. Moore, J. Sessoms, P. Macy

"A South American nickel mine has been producing a nickel concentrate that also contains copper and iron (15 percent nickel, 5 percent copper, 28 percent iron) for the end use of stainless steel production. A critical specification for the quality of the steel is the iron to magnesium oxide ratio (Fe:MgO), with a ratio of below 3.5:1 having a substantial impact on the nickel value. This nickel concentrate producer historically mined the sulfur-rich mineral pyroxenite but had been forced to move to a magnesium oxide/silicate (MgO/SiO4)-rich mineral harzburgite, resulting in nickel recovery being reduced to around 50 percent to maintain the required Fe:MgO ratio. In this study, ore mineralogy, water chemistry and the chemistries associated with the flotation process were evaluated in an effort to increase nickel recovery while maintaining the Fe:MgO ratio according to specification. New chemistry was introduced with the specific goal of complexing with the MgO and retarding its interaction with the bubble flow in the flotation process.IntroductionGlobal nickel production in 2011 totalled to 1,770,000 tons, according to the Raw Materials Group (2013). From 1950 to 2005 there was an aggregate 4.4 percent increase in nickel production, with a market-value high of $1,000/ton nickel reached in 1998 (Mudd, 2010). Approximately 65 percent of nickel production is consumed by the stainless steel industry, with 12 percent of the remainder used in super alloys or nonferrous alloys. Nickel imparts corrosion resistance, temperature resistance and other benefits to its alloys (Table 1) (Oberg, 1996; Cáceres, 2003). The dominant types of nickel-bearing ores are classified as either laterites (limonite: nickel-iron oxide; and garnierite: nickel hydrosilicate) or magmatic sulfide deposits (pentlandite: iron-nickel sulfide) (U.S. Geological Survey, 2013a, 2013b). In 2012, about 40 percent of the nickel ore mined was sulfidic-type ores and about 60 percent was laterite. The processing of laterite ore is expected to continue to increase as the availability of sulfidic ores continues to decline."

Jan 1, 2015

By R. A. Haney

The Mine Safety and Health Administration (MSHA) has conducted studies both in coal and noncoal mines to evaluate methods for sampling and separating diesel particulates from mineral dust aerosols. The agency is investigating size separation techniques to distinguish between diesel particulate and respirable coal mine dust. Additionally, ashing techniques have been used to distinguish diesel particulate from mineral dust in metal and nonmetal mines. As part of these studies, personal exposures to diesel particulate for various mining occupations have been measured. This paper describes the measurement techniques and summarizes the exposure levels for various underground mining operations.

Jan 1, 1990

By Arash Dahi Taleghani, Pooyan Asadollahi

Slurry walls, also known as diaphragm walls, are commonly used as temporary and/ or permanent support of excavation for construction of shafts in soft ground. Through case history, this paper demonstrates economical benefits of disregarding long-term structural contribution of the slurry walls particularly in severe environmental condition. In addition, for temporary slurry wall shaft systems, possibility of using steel fiber, synthetic fiber or additives in lieu of temperature/shrinkage reinforcement is discussed with detailed analysis. Finally, the paper will be concluded by introducing unreinforced slurry wall shaft system using newly developed/patented concrete additive.

Jun 13, 2021

By Rusdian F. Kayadoe, Michael B. Hutahaean, Sandi A. Firmanulhaq

Deep Mill Level Zone (DMLZ) mine is located in Papua, Indonesia operated by PT Freeport Indonesia (PTFI) with approximately 1,500m below surface. The ore body extend 1230m width from northwest to southeast by 300–400m length east-west. The mine currently produces at full production of 80,000 tons per day until 2041. Part of the extension of current active production block and mitigation sits 225 m above the production block 1 (PB1) and 2 (PB2A and PB2B) which located in 2590L, named production block#4 (PB4W and PB4E). As the mining continues at PB1N, PB2A, and PB2B, the cave growth vertically and laterally to south perimeter of the footprint affecting the integrity of PB4W/E footprint. Currently, PB1N and PB2N are in active production whilst PB4E development continues from South against PB1N cave, as can be seen in Figure 1. A slight overlapping between PB1E and PB4E intentionally to promote cave connections between the two caves. Despite low stress model in the PB4E near existing caves, the PB4E cave propagation expected by the large strain and will be propagating in tension failure to the PB1E cave. Hence, designing the drill drives edge and first drawbell location as close as possible to the PB1E cave is necessary to guarantee cave connection. Since PB4 footprint development commenced in December 2021, there have been a substantial cave propagation observed from existing downhole monitoring. As the PB4 footprint designed perpendicular to existing DMLZ PB1 cave, adjustment of the development edge design is necessary to reflect the progression the loosening zone propagation to the South. Final life of mine design for extraction, undercut and ventilation level were decided in October 2023 considering latest update cave (fractured/ yielded) boundary. Numerical model of potential rock mass damage also aids the decision to locate the drift edge design. Predicting the cave progression impact is critical to both production at the existing active blocks and development of the new area. The use of cave shape data from year 2021–2023 gives an insight of the cave shape estimation at the end of 2024 when the undercut drift will be developed. This paper presents actual cave growth of active production blocks and its relative vertical progression impact as the result of drawing in order to plan for acceptable rate and provide mitigation once the minimum acceptable rock mass condition and minimum pillar threshold achieved.

Feb 1, 2025

By Ashish Ranjan Kumar, Barbara Arnold, Luis Sanchez Gonzalez

The health and safety of miners is critical in the industry. Prolonged exposure to dust-laden air results in irreversible ailments like pneumoconiosis that have a severe impact on their lives. Operations use various personal protective devices (PPEs) to alleviate their exposure to respirable dust. Powered Air Purifying Respirator (PAPR) is one such device that uses high- efficiency filters and positive pressure masks to shield miners from airborne contaminants. Used in the medical and other industries, these respirators efficiently protected healthcare workers during the COVID-19 pandemic. Recently, the mining industry has shown a growing interest in adopting this PPE to ensure safe working conditions for the miners. We present an introduction to the PAPRs and discuss their dust capture efficacy in this manuscript.

Feb 1, 2025

By T. R. Kostecki, A. J. S. Spearing, G. S. Esterhuizen, K. V. Jessu

Discontinuities are geologic occurrences in rock and when present within a pillar, reduce the strength of the pillar. Empirical formulas that are commonly used to determine pillar strength do not explicitly take into account the presence of discontinuities and thus can overestimate the pillar strength. The effect of discontinuities on the strength of pillars has been investigated using numerical models, but in these models, the discontinuity strike was parallel with the pillar faces. In this study, fully three-dimensional hard rock pillars were simulated using numerical modeling to understand the effect of the discontinuity dip direction on square and rectangular hard rock pillars. Based on the results, recommendations to assess a pillar’s strength in the presence of a discontinuity are discussed.

Jan 1, 2018

By Jin Zhao, Weijie Wei, Jinwang Zhang, Xiaohang Wan, Shengli Yang

Reasonable mining-retention ratio (ratio of room width to pillar width) is vital to recovery rate and stope stability in underground mining of solid potassium salt deposits. Based on the engineering background of a solid underground potassium salt mine in Khammouan Province, characteristics of the plastic zone of the pillar, and the variation of recovery rate and stope stability under different mining-retention ratio conditions are discussed. The results show that compared with current room width (8 m) and pillar width (10 m), the optimization method of improvement of stope stability. The research results are helpful to recover as much solid potash resources as possible under the premise of ensuring the stability of stope.

Jun 25, 2024

By Patricio Vergara Lara, Jorman Barrera

The selection of the production level elevation is one of the most critical strategic decisions faced by large-scale block or panel caving projects. This elevation largely affects project timelines, capital expenditures, resource recovery, and may even constrain the mine’s maximum production capacity. Over the years, many computational tools have been developed to assist in this decision, most of them based on the same principle of maximizing the project value given its production level elevation. However, for large and inclined deposits, or those extending significantly in the vertical dimension and where extraction cannot be achieved from a single level, traditional selection techniques involving multiple production horizons often lead to suboptimal results. This paper proposes a methodology ensuring that the selection of production level elevations in a multiple horizons (“lifts”) case is globally optimized. Input parameters include economic and cost variables, maximum extractable column height, and deepening costs. The methodology is demonstrated through a real case study to illustrate its potential impact on project value.

Feb 22, 2026

By R. E. Doerr

The successful technical demonstration of coarse coal slurry transportation at Consolidation Coal Company's Loveridge Mine in West Virginia suggests that it is now appropriate to seriously consider this technology in other applications, especially the transport of ' coal in surface mining. Early examination indicates that coarse coal slurry transport may be highly competitive with existing haulage systems, depending on a number of factors. These factors are not yet completely defined, but certainly will include production rates, coal physical and chemical properties, terrain, soil conditions, climate, water availability and quality, availability of skilled labor and other economic considerations impacting the existing haulage systems.

Jan 1, 1983

By H. W. Gao

During the last decade, the feasibility of applying the in situ leaching technology to the recovery of copper from deeply buried deposits containing chalcopyrite has received much attention.(1-4) The major incentive for using this technology is that under certain circumstances, copper in deep underground deposits, which cannot be mined economically by conventional means, can be recovered economically. Basically, this technology involves rubblization of the deeply buried copper ore body followed by in-place leaching of the rubblized copper ores. Rubblization of the ore can be achieved by some suitable method such as the use of block caving mining. The rubblized chimney is then filled with water until the original water level is reached. Leaching occurs when the eater saturated with oxygen is introduced into the chimney- and flows through the fractured rock masses and within pores of rocks. As the dissolved oxygen oxidizes the primary sulfides, heat is generated. Because of low conductivity of the surrounding rocks, the generated heat is able to raise the temperature of the chimney. The increase in the temperature of the chimney and the relatively high content of dissolved oxygen in the leach solution under high hydrostatic pressure will result in an enhanced dissolution of the primary sulfide minerals. To ensure a successful application of the in situ leaching technology, a complete understanding of the effects of the ore particle size distribution, ore grade mineralogy, temperature, pressure, lixiviant concentration, pH, etc. on the rate of copper recovery is necessary so that copper can be recovered efficiently and the amount of copper extracted can be predicted. These can be achieved through mathematical modeling of the in situ leaching process and conducting laboratory tests. In this paper we will present a mathematical model that simulates the in situ leaching process as depicted in Figure 1. To model this process properly, not only the 'kinetic and thermodynamic aspects of leaching chemistry must be known, but the effects of heat generation, the physical aspect of fluid flow and other related multicomponent transport phenomena must be considered. Furthermore, since most factors involved in the leaching process change with time, a leaching system must be described using unsteady state equations.

Jan 1, 1981