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By J J. McEwan

Silver tarnishes readily in common atmospheres and is accelerated in humid atmospheres. Tarnish is the formation of silver sulphide on the surface of silver when it is exposed to a wide range of sulphur-containing atmospheres. Tarnish is unattractive and highly undesirable, and can be removed either with a silver polish or a chemical dip. Dips are generally only recommended when heavy black tarnish cannot be removed with a polish, and care must be taken during cleaning because these can contain aggressive chemicals and give off hazardous and unpleasant smelling fumes. Polishes work best for large areas of plain undecorated silver, and form part of a regular cleaning programme. Some polishes contain chemicals that inhibit tarnishing, but these generally only have a short life. Several methods have been developed to reduce tarnish formation on Silver; these include alloying, surface treatment, and coatings. The authors evaluated a range of self-assembled monolayer (SAM) surface treatments and coatings in earlier research. Four treatments/coatings increased the time to noticeable tarnish by more than ten fold, and the results were reported at the International Corrosion Congress (ICC) in 2005, and at the Mint Directors Conference (MDC) in 2006. SAM treatment using 95% 1-hexadecanethiol (C16H34S) was found to give good anti-tarnish performance and showed potential for the commercial treatment of Sterling silver. Therefore research was performed to optimise the methods of application of this type of coating to provide an easier, faster, and more-user friendly technique to provide an anti-tarnish treatment. Keywords: silver, tarnish resistant coatings.

Jan 1, 2006

By Phil D. Newman, Robert J. Pine, Kevin Ross

The Stratoni Operations in northeastern Greece rely on a selective backfill method to exploit high-grade lead-zinc deposits. Underhand cut and fill often results in spans approaching 6-9 m (depending on the mining method employed) and a competent backfill is required to avoid dilution problems. Cement consumption represents a significant mining cost and through improving the control of the backfill batch preparation, the cement content could be greatly reduced without jeopardizing the grade control. A new distribution system was installed and a QAIQC system designed in cooperation with the operators to allow a wide range of backfill recipes, providing cost savings to the mine. A review of possible failure modes and the consequent strength required for the chosen mining method was also completed and indicated potentially significant cement content reductions. The calculations are supported by 12 years of experience at the mines which provides a valuable insight into the applicability of the approach developed.

Jan 1, 2001

INTRODUCTION This paper was originally presented at the Platinum Adding Value Conference, held at Sun City from the 4th to 6th October 2004. Narrow reef mining may not be applicable to the base metal operations in Zambia, however, it is considered that the methodology used is equally appropriate to the development of technology and mining methods in mining environments other than narrow reef mining. The purpose of this paper is to explore the integration of technology and stoping systems. For the last hundred years the South African narrow reef mining industry has battled to control working costs in a labour intensive industry. It is only through the application of appropriate technology that change will occur. Stoping systems, because it is the stoping method and methodology that is at the heart of the mining system. Introduce a different technology that results in a more efficient stoping system and the mining system will look after itself. The technology applied to stoping in narrow reef mining, over the last 100 years, can be categorised as follows: ? The introduction of pneumatic rockdrills early this century. The cumbersome rig mounted units being replaced by smaller, lighter, hand held units that were then made easier to use with the addition of an air leg. (The so called Swedish method of mining.) As late as the early 1970s some drilling was still being carried out without the assistance of an air leg. ? Scraper winches to replace gravity and shovels to move rock both in the face and the gullies were first introduced in the late 1920s. ? Hydraulic props installed close to the face and capable of applying force against the hangingwall as well as yielding in a controlled manner under dynamic load arrived in the 1960s. In many instances these have now been replaced by yielding elongates fitted with water hydraulic tensioning devices. ? Some people argue that the introduction of tungsten carbide inserts, to improve drilling, was equally important.

Jan 1, 2005

By Cox I

Raiseboring is a technique that has become popular in modem mining engineering since the early 1960s. A study has been undertaken at the University of Queensland to determine important factors affecting the optimum diameter of raisebored shafts, excluding local parameters such as the maximwn excavation size that a particular rock type can safely accommodate.This model is used to examine each of these factors and the results indicate that the optimum diameter for raisebored shafts is generally between four and six metres.

Jan 1, 1991

By M J. Daniel

Mineral resources all over the world are often heterogeneous and have variable ore properties and ore grade. As a result the ore processed in concentrating plants varies over the life of mines. Consequently the circuits often suffer from bottlenecks typically at the stages of crushing, semi-autogeneous (SAG) and ball milling. Bottlenecks may be remedied with equipment retrofits, however, design engineers should consider a phased approach to the circuit design that delays initial capital expenditure over the life-of-mine. This paper deals with the debottlenecking of existing mineral processing plants by means of high pressure grinding roll (HPGR) applications. It also deals with the use of innovative flow sheet designs using HPGRs for the design of Greenfield plants by engineering or mining companies. In the case of Greenfield plant design an analysis with respect to energy efficiency and operating cost (OPEX) is presented. The analysis compares the performance of SAG based circuits against HPGR circuits that may be influenced by variable ore properties. Globally about 600 HPGRs are installed in various applications in the cement and minerals industries. In excess of 100 of these HPGRs are used since the mid 1980s for crushing and grinding of various ore types including æhard rockÆ applications. HPGR technology is mature enough to be considered as an ideal debottlenecking device. HPGRÆs are versatile, they have a low installation footprint and they are flexible in its machine settings (pressure, roll speed), which can be adjusted to react to ore variations whilst maintaining a high throughput. Examples for the benefits of using HPGR in terms of energy efficiency and operating costs are presented by this paper. æEco-efficientÆ flow sheets and sustainable development initiatives are linked to energy savings as an æenergy costÆ and benefit to the environment. Energy savingsÆ can also be analysed in terms of the ædollar costÆ (OPEX) savings. This paper demonstrates that HPGR is more energy efficient and may reduce the overall grinding energy requirements in the order of 16 per cent depending on the target grind size and ore properties. The HPGR is more cost efficient and may reduce overall grinding costs by as much as 19.3 per cent depending on the cost of energy, grinding media and the rate of grinding media wear in the comminution circuit.

Jan 1, 2009

By Y Ren

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Aug 12, 2013

By R. Jacobs, R. E. L. Pobe

The Moab Khotsong Metallurgical Complex comprises a gold recovery circuit (Noligwa Gold Plant) and a uranium recovery circuit (South Uranium Plant). The metallurgical complex employs the reverse leach technology for the recovery of uranium; specifically, uranium extraction prior to gold using acid leaching processing. The inherent uranium species in the ore are uraninite, coffinite and brannerite. The slurry that has been subjected to the uranium leach is further subjected to solid-liquid separation to separate the uranium in a solution through counter-current decantation and the solids (solids carrying all the gold), which are repulped and returned to the gold plant for gold processing. The uranium leaching process is critical to the uranium playing a pivotal role as a value adding by-product to the gold operation. The benefit of adopting this reverse leach process, for improved gold recovery, is that it exposes gold particles occluded within the uranium matrices and avails them for cyanidation. However, the drive for operational efficiency in uranium extraction must be weighed against the incremental operating cost against the backdrop of depressed spot uranium market prices. Over the years, efforts were directed at maintaining the benefit of extracting uranium to enhance gold recovery and simultaneously, optimising the operating cost model for the uranium operation to remain relevant to the gold operation. The aim of this paper and the corresponding presentation is to give an account of the uranium processing optimisation journey embarked on over the years; namely, the operational tradeoffs made in the process of ensuring that uranium continues to add value to the gold operation. These challenges were faced while striking a fine balance between processing cost and operational efficiencies against the prevailing depressed uranium spot market prices. Mineralogical- and laboratory tests conducted form the support basis for the results and observations articulated in the paper. Keywords: By-products, gold extraction, reverse leach benefit, uranium extraction

Jan 1, 2020

By R. Jacobs, R. E. L. Pobe

The Moab Khotsong Metallurgical Complex comprises a gold recovery circuit (Noligwa Gold Plant) and a uranium recovery circuit (South Uranium Plant). The metallurgical complex employs the reverse leach technology for the recovery of uranium; specifically, uranium extraction prior to gold using acid leaching processing. The inherent uranium species in the ore are uraninite, coffinite and brannerite. The slurry that has been subjected to the uranium leach is further subjected to solid-liquid separation to separate the uranium in solution through counter-current decantation and the solids (solids carrying all the gold), which are repulped and returned to the gold plant for gold processing. The uranium leaching process is critical to the uranium playing a pivotal role as a value adding by-product to the gold operation. The benefit of adopting this reverse leach process, for improved gold recovery, is that it exposes gold particles occluded within the uranium matrices and avails them for cyanidation. However, the drive for operational efficiency in uranium extraction must be weighed against the incremental operating cost against the backdrop of depressed spot uranium market prices. Over the years, efforts were directed at maintaining the benefit of extracting uranium to enhance gold recovery and simultaneously, optimizing the operating cost model for the uranium operation to remain relevant to the gold operation. The aim of this paper and the corresponding presentation is to give account of the uranium processing optimization journey embarked on over the years; namely, the operational trade-offs made in the process of ensuring that uranium continues to add value to the gold operation. These challenges were faced while striking a fine balance between processing cost and operational efficiencies against the prevailing depressed uranium spot market prices. Mineralogical- and laboratory tests conducted form the support basis for the results and observations articulated in the paper.

Jan 1, 2020

By Larry G. Twidwell, Corby G. Anderson, Camille M. Fleuriault

"The selective precipitation of iron as ammonium jarosite is a well-established industrial technology in base metals hydrometallurgy. It is a key technology in minimizing iron tenors which would be disruptive to downstream processing. It also provides a more readily filterable iron solid to better facilitate materials handling. This paper elucidates the fundamentals behind industrial iron precipitation. Then, the details of the successful optimization of an industrial ammonium jarosite circuit are presented.HYDROMETALLURGICAL IRON REMOVAL FUNDAMENTALS Iron is the fourth most abundant element in the Earth’s crust (5% by weight) and is often found in complex ores such as sulphide-bearing formations. Iron represents an issue though during leaching, a technology which is widely used for the treatment of this type of ore: •,Iron has the particularity of forming hydroxides when leached under certain conditions. Iron hydroxides form a viscous gel, which is difficult to filter and traps valuable elements such as silver. •,Iron is solubilized along with other metals and interferes with the subsequent extraction steps. As a result, purification of the pregnant leach solutions is required to achieve economical extraction of base metals. In the 1960s, metallurgists developed iron precipitation processes for solution purification (Habashi, 1999). Nowadays, precipitation of iron bearing species, such as goethite, hematite or jarosite, has become one of the most common methods used in the industry to purify leach liquors. To be suitable, the precipitate has to be readily filterable and thus must not be too fine of particle size. Precipitation can take place in autoclaves at medium to high temperatures, under an oxygen or air overpressure (Tourre, 1984, Fleuriault 2016, Fleuriault Anderson Shuey, 2016))."

Jan 1, 2016

By Ioannis Nicolaou

This paper demonstrates the method of approach for the optimization of such filters. This does not only incorporate the proven and simple recently developed equations for the calculation of the solids throughput, the residual moisture and gas throughput, but also introduces equations for the calculation of the specific product costs for both vacuum and hyperbaric filtration under consideration of the influences exerted by the filter compressor and a possible thermal drying. An easy-to-use method is offered which incorporates a special graphic representation concerning the plotting of the target parameters in dependence of the pressure difference with which the optimal process pressure difference can be established, independent of the specific cake permeability or product fineness. Finally, the optimization method is exemplarily demonstrated for a concrete application.

Jan 1, 1995

By Mojtaba Ghorbannezhad, Abbas Sam, Soroush Arabzadeh

One of the dewatering methods in mineral processing plant is filtration system. Disk filters are included the porous surface with pressure drop on both sides, Water in the pulp passes through the surface and solid particles remain as a cake on it. Wet concentrate production of magnetite processing plant at Golgohar Mining and Industrial Company with solid tonnage of 160 ton per hour and 49% solid amount contains 166 m3/h of water. In the present study, in addition to studying disc filter performance, the effective parameters on cake moisture were studied using Vacuum Bottom-Feed Leaf method (in the laboratory scale). Optimization was performed using the Taguchi method. The results showed that the cake moisture is reduced by increasing particle size and solid percentage (because of specific resistivity reduction), while the rate of cake formation and its thickness are increased. Also, it was found that by increasing pressure, the cake moisture is reduced and cake formation rate and its thickness are increased. In this study, the effect of fabric texture was also examined. Lowest cake moisture was obtained in condition of using compressed plain fabric with mono-multi filament fibres, pressure at 75kPa, solid percentage of 65 to 70, particle size (D80) equivalent to 123µm and disk rotation speed of 1.25 rpm.

Jan 1, 2014

By A. Haxhiaj, Mitovica, E. Haxhiaj

"The paper discusses problems encountered during the release and possibility of using the thermal gas quantity Mathematical models are used to calculate the positive thermal effects of the gases and losses of thermal quantity with gases in the melting process of electric furnaces. The paper discusses in details the percentages of CO, CO2, H2S, O2 and the humidity in gases and their impact on the technological process in electrical furnaces in Drenas. The paper also confers the quantity and temperature of gases, the transfer of thermal quantity and dust with gases in the environment. The paper presents the percentage of humidity in the load which is added in electric furnace for melting and its impact on thermal and environmental balance in the technological process of melting in electric furnaces. Key words: Furnace, load, temperature, humidity, gases.IntroductionNickel easily reacts with gases in the atmosphere of the furnace in which the nickel ore is processed. Such reactions can explain challenges in producing high quality nickel. Reductive atmosphere with the surrounding gases composed of sulphurous anhydrite has harmful effects on the production of nickel. This is mainly due to solubility of hydrogen as well as nickel oxide in the melted metal. Nickel reacts with carbon monoxide and forms carbide of nickel and nickel oxide which dissolve in the melted metal. Carbon monoxide also dissolves in the melted metal. The presence of carbon dioxide and water vapor in the atmosphere of the furnace impact the decrease of acidity in reductive atmosphere of the furnace. The carbon dioxide reacts with nickel and forms nickel oxide and carbon monoxide. Water vapor reacts with nickel and forms hydrogen and nickel oxide that have negative impact on the structure of nickel and its alloys. In this paper the analytical and experimental analyses are proposed that lead to minimization of the negative effects of gasses and humidity in the melting process. As the practical example, the electrical furnace in Drenas is analyzed.1. The Load and Its CompositionThe basic function of the rotational furnace is drying and reductive roasting of the ore which directly is loaded into the electrical furnace for melting. It is important to mention that the degree of roasting and pre-reduction of iron-nickel oxides is reached if the roasting process of the load in the rotational furnace is done at the temperature of 900°C to 1000°C, with the reductive atmosphere in the furnace and with minimal amount of oxygen in the processing gas. The optimal process of roasting and pre-reduction of the load in its mass is around 13 wt%. With the removal of the humidity and the sterile pare of the ore, with the positive impacts in utilization of the thermal and electrical energy in the melting process in electrical furnaces."

Jan 1, 2013

By M. B. McClenaghan, O. P. Lavin, Ian Nichol

"Abstract-Exploration in most areas of Canada has to contend with problems posed by glacial overburden. In many areas exploration for gold has been based on the sampling of tills, frequently by deep overburden drilling, and analyses of heavy mineral concentrates. Notwithstanding the significant role that till geochemistry has played in the discovery of some important gold deposits over the last few years, increased appreciation of the nature of the glacial history and stratigraphy and the character of gold within till has led to the recognition of a number of ways whereby the effectiveness of exploration can be improved upon.In order for till geochemistry to be useful in exploration, a number of conditions must be fulfilled, including:1. mineralization, or alteration halo related to mineralization, subcropping at the bedrock /over­ burden interface; 2.glacial erosion and dispersal of a recognizable signature of mineralization into the glacialsediments; 3, preservation of glacial sediments containing this geochemical component (trace metal or mineral) at positions subsequently selected for sampling (normally drill sites); 4. correct identification of specific till units and associated ice movement history; 5. collection of adequately large and representative samples; 6. appropriate sample preparation and processing; 7, appropriate geochemical analyses; and 8. correct data processing and interpretation.While we have no control over the first two geological conditions, and only limited controlover till availability, we can control the quality and thoroughness of sampling, sample identification, sample preparation, analysis and interpretation. In particular attention needs to be focussed on obtaining a large enough sample to be adequately representative, an unbiased sample must be collected, together with appropriate sample processing, analysis, data processing and interpretation. It is considered that by modifying or extending existing approaches to gold exploration the chances of exploration success can be increased. In particular, analyses of both the heavy mineral and minus 63 ?m fractions of till is recommended because gold in till may occur in different size fractions."

Jan 1, 1992

By M. B. McClenaghan, O. P. Lavin, Ian Nichol

"Exploration in most areas of Canada has to contend with problems posed by glacial overburden. In many areas exploration for gold has been based on the sampling of tills, frequently by deep overburden drilling, and analyses of heavy mineral concentrates. Notwithstanding the significant role that till geochemistry has played in the discovery of some important gold deposits over the last few years, increased appreciation of the nature of the glacial history and stratigraphy and the character of gold within till has led to the recognition of a number of ways whereby the effectiveness of exploration can be improved upon.In order for till geochemistry to be useful in exploration, a number of conditions must be fulfilled, including:1. mineralization, or alteration halo related to mineralization, subcropping at the bedrock/overburden interface;2. glacial erosion and dispersal of a recognizable signature of mineralization into the glacial sediments;3. preservation of glacial sediments containing this geochemical component (trace metal or mineral) at positions subsequently selected for sampling (normally drill sites);4. correct identification of specific till units and associated ice movement history;5. collection of adequately large and representative samples;6. appropriate sample preparation and processing;7. appropriate geochemical analyses; and8. correct data processing and interpretation.While we have no control over the first two geological conditions, and only limited control over till availability, we can control the quality and thoroughness of sampling, sample identification, sample preparation, analysis and interpretation. In particular attention needs to be focussed on obtaining a large enough sample to be adequately representative, an unbiased sample must be collected, together with appropriate sample processing, analysis, data processing and interpretation. It is considered that by modifying or extending existing approaches to gold exploration the chances of exploration success can be increased. In particular, analyses of both the heavy mineral and minus 63 µ m fractions of till is recommended because gold in till may occur in different size fractions."

Jan 1, 1992

By Richard R. Klimpel

INTRODUCTION Previous papers by this author have discussed some of the difficulties involved with optimizing the performance of industrial flotation circuits, e.g. Klimpel (1988, 1989). The two major problems seem to be: 1) the inherent "systems" nature of the froth flotation process which leads to a great deal of self-compensation among the various operating options available and 2) the inherent variations in mineralogy, water chemistry, etc. that always seem to be present in industrial operations. In particular, the influence of reagent dosage has been emphasized in the above referenced work including an industrial system interaction denoted as the R/K trade-off, Klimpel (1984, 1987). Using a simple two parameter model for fitting time - recovery data, Klimpel (1980): [ ] where r is cumulative recovery at time t or at the t th cell, R is the long-term equilibrium recovery and K is the first-order rate of mass removal from the cell (time ), the definition of the R/K trade-off with increasing reagent dosage can be given as follows: at low dosages both R and K increase, at intermediate dosages R continues to increase but K starts to level out, and at high dosages, R may flatten out or still continue to increase but K starts to decrease, sometimes rather quickly. An illustration of this effect in a batch laboratory flotation cell is given in Figure 1. The purpose of this paper is to give a detailed plant illustration of this R/K trade-off phenomena with changing collector dosage which shows just how highly interactive the grindinglflotation system in sulfide mineral processing really is. This is one of about 20 plant level case studies that are being presented and evaluated in an upcoming book, Klimpel (1990). The particular study given here was completed in late 1979 on a copper ore of head grade 0.93% Cu. The frother being used was Dowfroth* 250 at a constant dosage of 0.15 g for each ton of solids feed to the rougher bank and the slurry pH was 10.2. The motivation of the study was to better understand the relationship of changes in feed rate (hence in particle size and state of liberation) with variations in collector dosage (potassium amyl xanthate). The major concern was to determine how much extra economic benefit could be gained by better utilizing the existing grinding mills and rougher bank consisting of eight identical cells. The remainder of the flotation circuit was also studied, including regrinding of rougher tails, but did not prove as critical as the rougher bank operation itself. It appeared from an overall economic viewpoint, the battle was being won or lost in the manner in which the rougher bank was being operated. This was not to minimize the roles of the scavenging and cleaning circuits but those portions of this particular circuit could be rather obviously operated to achieve maximum benefit given the specific output of the rougher bank. A special attempt was made to maintain constant ore type throughout the entire test program. Eight specific test conditions were evaluated including three different feed rates (and hence three different size distributions) to flotation. Tables 1 and 2 summarize the eight test conditions and overall recovery results at the end of the rougher bank for each test. A single test consisted of at least three consecutive eight-hour shifts operating at steady-state with composite cell lip samples taken over the final eight-hour shift. "Trademark of The Dow Chemical Company

Jan 1, 1990

By D. R. Lawrence

A method for the calculation of the economic optimum spacing of raise connections in 'scattered' mining layouts is described. The method of calculation and the results obtained in a case study are presented. An indication of how the overall optimum spacing (which satisfies both economic and geological considerations) can be determined is also given. " The case study demonstrates that, even with the present strike-cleaning systems,significant savings in working costs can result from an increase in the spacing between raise connections. Furthermore, improvement of the present systems would result in a considerable increase in these savings.

Jan 1, 1983

By U. M. J. Boin, W. L. Dalmijn, T. P. R. de Jong

"This paper explores the complex interrelationship between the resource cycle, recycling and metal production as a function of economics, environmental legislation, and product design. It is argued that central to optimising this resource cycle lies the control in particular of physical separation plants by the application of advanced sensor technology and sorting equipment, as well as suitable control and sampling algorithms supported by optimising mass balance models.Metals are produced through a long chain of processes. For primary resources, metals production goes through mining, mineral processing, ore smelting, conversion and refining steps or via low temperature hydrometallurgical processes, or a combination of both pyro- and hydrometallurgical operations. For the recycling of resources, metals are separated and recovered from metal scrap, which plays an increasingly important role in the world. Metals after being produced, either from primary or recycling resources, have to be further refined or manufactured into various types of alloys and finally shaped into different products for the end-users. Since the end-user discards products the contained materials find their way back into the resource cycle as scrap. Therefore, controlling the metallurgical reactors also controls, in a much broader sense, the material quality in the complete metals cycle, from the production phase, to the end-use phase, up to the recycling phase (Reuter et al., 2003). The recycling phase includes separation of materials into saleable intermediate products, which are reintroduced into the production phase as a recycling resource. Therefore, the metallurgical processes in each unit operation in the metals production and processing chain have to be controlled, so as to achieve optimal performance of high product quality, low energy and materials consumption, and low environmental impact."

Jan 1, 2003

By M. Asghari, R. Amiri, A. Haratian, S. Haji

The aim of this investigation is the evaluation of optimising the Shahroud copper ore beneficiation plant near the Iranian city of Shahroud, by means of a sensor-based ore sorter applying X-ray transmission technology. Currently, this plant’s feed capacity of 52t/h produces 0.5t/h copper concentrate with a grade of 30% and copper recovery of 85% from a feed grade of 0.36%. By applying an X-ray transmission-based (XRT) sorter, it is possible to preconcentrate the feed and remove the gangue materials before entering the plant, enabling the production rate of concentrate to be increased. In this study, the obtained representative sample from the plant was preconcentrated in particle size of - 75+10mm by using the X-ray sorter, thus the concentrate with Cu grade of 0.85% was obtained. Therefore, by using of X-ray sorter the Cu grade of plant feed was increased to 0.48%. By increasing the feed grade from 0.36% to 0.48%, and considering a Cu recovery of 85%, the production rate will be increased from 0.48t/h to 0.61t/h. Therefore, the preconcentration by using the XRT sorter increases the production rate by 27%. Keywords: Optimisation, preconcentration, copper, X-ray, sensor-based ore sorting

Jan 1, 2020

By Changqing Su

A batch incubation experiment has been carried out to investigate the optimal condition for the microbial remediation of hexavalent chromium (Cr(VI)) in soils contaminated by chromate ore processing residue at Hunan Iron-Alloy Factory in China. The optimal condition was obtained by comparing the remediation efficiency of Cr (VI) by indigenous bacteria under different culture media, the quantity of nutrient sources, the pH and the temperature. The results indicated that glucose and yeast extract was the optimal component of culture medium and the quantities of the above components were 8 g L-1 and 13 g L-1, respectively. The optimal temperature and pH value were 30_ and 10.0, respectively. A bioreactor was operated under the optimal condition to evaluate the efficiency of Cr(VI) remediation in the contaminated soil. The result showed that water soluble Cr(VI) in soils was reduced from 320 mg kg-1 Cr(VI) of the initial concentration to below detection limit after 30 h in a bioreactor. Thus, there is a large potential to make bioremediation for the reduction of Cr(VI) to Cr(III) by the addition of optimal culture medium under aerobic condition.

Jan 1, 2010

By Ernest Koenigsberg

In 1961 Lerchs and Grossman presented a method, based on graph theory, to determine the optimum ultimate pit limits for an open-cast mine. At the same time they demonstrated a dynamic programming algorithm for the optimum pit limits for a two-dimensional open-cast mine. Since then many methods for determining optimum limits for three-dimensional mines have been programed, and even more have been reported in the literature. The methods include computer "simulation" of the manual methods used by engineers, the development of sets of conic sections and fitting to exclude overlap, integer linear programming (and its equivalent network flow model), and dynamic programming. Many of the methods do not guarantee optimal solutions but seem to satisfy the user. Other reported methods have never been applied, partly because they did not yield optimal solutions. We have developed a three-dimensional dynamic programming algorithm which requires a single pass through the data. Large problems can be solved on a small computer because only a small part of the data is required at any time. In this paper we will review the state of the art and to demonstrate the connection between linear programming (and network flow) models and the dynamic programming method.

Jan 1, 1982