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By C Barton, B Randall, T Weldon, M Lefler

FLSmidth-Summit Valley Technologies has been a leader in gold processing equipment for nearly two decades. Over the past several years an extensive research and development effort has led to improvements in Mercury Abatement systems and process efficiency in Adsorption Desorption and Regeneration (ADR) or "Carbon" plant operations. Two technologies will be discussed that are focused on efficiency improvements followed by an explanation of Mercury Abatement systems. Gold and silver can be desorbed from carbon in several ways. FLSmidth has made significant improvements to the Pressure ZADRA process allowing for lower energy consumption and lower capital costs. This patented process is known as the Split-ZADRA Strip method. Split-ZADRA allows a plant to elute loaded carbon in a semi-continuous fashion. This increases the grade of the Pregnant Strip Solution, improves electrowinning efficiency, reduces capital equipment costs, and reduces energy requirements. During desorption and electrowinning for the Pressure ZADRA process, the pressure and temperature of the circulating strip solution is changed multiple times. A self-contained heating and cooling system has been developed which decreases the energy requirements for elution. Mercury Abatement technology has become increasingly important in recent years. Along with FLSmidth Summit Valley Technologies' complete Mercury Retorting Systems, FLS-SVT has developed systems for the capture and removal of mercury from electrowinning cell and strip solution exhaust, Carbon Regeneration exhaust, and the dore furnace exhaust. This paper describes each of the technologies introduced above and their success in operational gold and silver mines. Case studies will be discussed showing the advantages of each specific technology as it applies to operations around the world. CITATION:Lefler, M, Weldon, T, Barton, C and Randall, B, 2013. Improvements in the mercury abatement and process efficiency of adsorption, desorption and regeneration gold processing operations, in Proceedings MetPlant 2013 , pp 468-478 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

By T. Scully

Since early days in coal mining, it has been known that some coals and the carbonaceous materials associated with them will heat and fire spontaneously. Many theories have been advanced to account for this phenomenon, but it is only within comparatively recent years that any scientific research has been carried out to determine the causes of this heating, the conditions which bring about its occurrence, and the reason why different coals heat with a varying degree of readiness. So far, this research has not cleared up these points entirely, but a great advance has been made in our knowledge of the matter. In general, any coal will fire spontaneously, although with a varying degree of readiness, provided conditions for its doing so are favourable enough. These conditions are that the coal must be in a fine state of division, that sufficient oxygen must be present for rapid oxidation, and that the air current passing must be so small that it is insufficient to carry off the heat produced by this oxidation. Many other minor factors, however, contribute to bring about spontaneous heating, either by producing initial heat themselves or by inducing the other major conditions.

Jan 1, 1931

By RICHARD L. HUMPHREY

IT IS proper that there should be a brief accounting of the stewardship which was entrusted to the Joint Conference Committee by resolution adopted by the. Organizing Conference on June 4, 1920, in part as follows: RESOLVED, that it is the sense of this Organizing Conference that the Joint Conference Committee should be entrusted with making provision for putting the conclusions of this Conference of engineers into effect, etc. Pursuant to this authority, the Joint Conference, Committee has acted as an Ad-interim Committee has- prepared, a synopsis of the proceedings of the Organizing .Conference, has edited and published the Constitution and By-Laws adopted by this Conference, and. has issued an invitation to become Charter Members of The Federated, American Engineering Societies; to the list of organizations to whom invitations had been extended to attend 'the Organizing., Conference. The Committee in connection with this invitation offered to the extent of its ability, such assistance as might be-desired; and arranged in many cases for one or more of its members to be present when the matter of membership in The Federated American Engineering Societies was considered. . .

Jan 1, 1920

By S. S. Gross

A program was conducted to determine whether sufficient quantities of the flame retardant, ammonium phosphate, could be incorporated in a water-based foam solution to prevent or delay reignition (burnback) without. significant degradation of foam properties. Up to 20% of mono and diammonium phosphate was added .to d high expansion foam solution. This mixture was applied as a high expansion foam to burning wood and coal samples. The effect of this mixture on burnback was laboratory tested by placing the wood or coal sample in front of a radiant panel. It was found that diammonium phosphate levels of 20% by weight prevented reignition without degrading foam properties. A field test was then conducted using a 20%, diammonium phosphate mixture and a control with no phosphate on a wood crib fire. The experimental foam did extinguish the crib fire faster than the control as evidenced by the smoke from the crib. However neither crib reignited.

Jan 1, 1982

By James Wm. White

Computer based dispatching in open pit truck haulage operations yields many benefits of current interest to mine management. The key tangible benefit is a substantial productivity increase with a given fleet of equipment or, alternately, a significant reduction in equipment required to meet production quotas. Other tangible benefits, depending on the operation, include minimizing rehandle, meeting several blending constraints simultaneously and ensuring a target plant feed rate. Intangible benefits include production forecasting, performance comparisons of trucks or shovels of different manufacture and extensive on-line report generation. Recent advances in mini and micro computer hardware and software and solid state electronics permit design and implementation of system features not feasible even a few years ago. Here we discuss many of these recent developments with emphasis on system aspects and dispatching algorithms.

Jan 1, 1983

By David Lynn Passmore

The reliability of mine operators reports to the Health and Safety Analysis Center of the U.S. Deparetment of Labor of days lost from work by injured miners is .267.

Jan 1, 1985

By Carl Barchet

INTRODUCTION Located on the Colorado River on the Nevada-Arizona border about 56 km (35 miles) southeast of Las Vegas, Nevada, Hoover Dam is a gravity arch dam 221 m (726') high for electric power generation and water supply. The head waters of the dam form a large reservoir, Lake Mead. The dam is equipped with two emergency spillways, one in the Nevada abutment and one in the Arizona abutment. Both spillways which are concrete lined and 15.25 m (50') in diameter, were intended for use only if Lake Mead is full and incoming flow of the Colorado River exceeds the discharge capacity of the turbines and regular bypass conduits. In the spring of 1984, a combination of rain and unusually rapid snow melt required the opening of the spillways for only the second time in the 50 year history of the dam. As in the previous use in 1942, the massive discharge of water through the tunnels resulted in severe damage to the concrete Linings of both tunnels. This damage is the result of cavitation which occurs as the discharge water flows at very high velocities over minor irregularities in the concrete lining. The U.S. Bureau of Reclamation has long been aware of the cavitation effect which occurs during these high volume discharges and has been studying solutions. One solution to the problem is to induce air bubbles into the flowing water to eliminate the vacuum associated with cavitation. This solution had been implemented at Yellowtail, Flaming Gorge, Blue Mesa, and Glen Canyon dams by constructing an aeration slot in the inclined portion of their spillway tunnels. Since the spillways of Hoover Dam were already in need of repair, the BUREC decided to construct similar facilities in each of the two 15.25 m (50') diameter spillways coincidental with the other repairs required.

Jan 1, 1987

By Kiyoshi Azuma, Hiroshi Kametani

Dissolution of a ferric oxide in acid solution is divided into two different types In the accelerated type dissolution proceeds in three stages 1) an inittal reaction during which the dissolved amount of oxide is nearly proportional to the cube root of time ; 2) an accelerated reaction: and 3) a final stage during which dissolution approaches completion. This course of dissolution gives an S-shaped curve in the above sequence OH a log weight percent of dissolved oxide against log time graph. In the parabolic type dissolution proceeds in four stages: first and second stages similar to those of the accelerated type; 3) parabolic-rate dissolution during which the dissolved amount of oxide is nearly proportional to the square root of time: and 4) a final stage. The effect of the kind of acid, the temperature of solution, and the concentration of acid was investigated. The results are discussed and a rate equation is proposed. AN attempt has been made to obtain some information on dissolution of a ferric oxide in various acid solutions. In view of hydrometallurgical processes the dissolution of ferric oxide is of less importance than that of zinc oxide or copper oxide in general. One of a few processes which intend to dissolve ferric oxide is an elimination of iron impurity from acid-insoluble materials. However, most leaching processes of oxide ores and cinders are accompanied with more or less dissolution of iron. According to Pryor and Evans1 the rate of dissolution of a ferric oxide in various acids decreased in the order of hydrofluoric acid > hydrochloric acid > sulfuric acid > perchloric acid. This order was in accord with the order of decrease of the complexing affinity of the anion for ferric ion,

Jan 1, 1964

By A. Tello

Variography was introduced by Dr. Pierre Gy to monitor a process, in the sixties. Later on, Francis Pitard extended this concept, building a complete system of variographic controls for different applications. Nevertheless, the existence of information about its use as a way to effectively control plants has been limited. There are infinite areas where variography and chronostatistics can be used. In this paper, two different cases related to gold and silver recovery, through well known but complex metallurgical routes are studied. The use of effective management of process variability software (EMPV) has shown to be a suitable solution to clarify problems at the plant and, consequently, a solution to the encountered problems has been proposed. Chronostatistics is like opening a new world to the metallurgist, making the process variability speak in a more comprehensive and in depth way. Once the ore has been extracted from the mine, sampling is necessary at each sequence of the metallurgical process involved. As a first example, leaching of the ore with cyanide in agitated tanks is another case of a complex metallurgy. The aim of the process is to know about residual values in the tailings in order to optimize process. As a second example, leaching of gold and silver in ore heaps, has to be optimized in terms of time, reagents consumption and, of course, in predicting a reasonable recovery. This last issue appears to be crucial. After cyanide leaching at the heaps, a carbon in columns process is involved, where there are a series of carbon loaded columns that are submitted to a dynamic process of load and unload, to finally deliver an enriched solution to the precious metal electrowinning plant. In both cases, variography has been a good approach to show metallurgists ways to improve the operation.

Jan 1, 2009

By Otis W. Freeman

Production of oil in Indiana during 1944 is estimated at approximately 4,950,000 bbl., a decline of 6 per cent from the preceding year. Shortage of labor and material, together with governmental regulations resulting from the war, largely account for the drop in output and limited new developments. Three new pools were discovered in the state during 1944. Two of these, New Harmony, South, and Hovey, West, are in Posey County. Six wells in the New Harmony, South, field produced 66,422 bbl. of oil last year. A third field, Cato, in Pike County, did not market the oil from its discovery well during 1944. Several wells discovered oil in the Henderson field of Jay County along the Ohio state line. An important south extension of the St. Thomas field in Knox County was discovered during the year. Active drilling took place in the Inman, East, and Upton fields, Posey County, both discovered in 1943. Twenty-two wells in Inman, East, produced 151,1gr bbl. in 1944 and 12 in Upton produced 107,052 bbl. Owensville, and especially Owensville, North, in Gibson County, made large gains in production as a result of active drilling. The Dodds Bridge field in Sullivan County continued good production from deep sands reached in 1942. The Griffin continued to be the largest producer among the oil pools of Indiana, accounting for 2,004,180 bbl., over 40 per cent of the state's output. The next largest producing fields are Mt. Vernon and New Harmony, both in Posey County. The largest gas well brought in during 1944 was in the Rockport field, Spencer County, and had an initial output of 2,680,000 cu. ft. per day. The most productive gas fields in Indiana are Rockport, Spencer County, Greensburg, Decatur County, and Unionville, Monroe County. Total production in the state is . hard to estimate, as considerable gas is consumcd in farm homes and for other local uses, and never is reported, but was near 1500 million cubic feet. Some oil from the Trenton field is also used locally and is unreported from pipe-line runs. A total of 606,145 ft. of new hole was drilled in Indiana in 1944. Most of the completions were in Posey and Gibson counties, although wells were drilled in 36 different counties. During the year 331 wells were completed. Of these, 145 found oil in commercial quantities and 28 were gas wells. The initial production of the 145 oil wells was 11,908 bbl. per day. Settled production would be less, of course. The largest wells reported during the year were two on the J. W. Mann farm, in the Mt. Vernon field, with a flush flow of 500 to 800 bbl. each.. Six pools, all small "one well" affairs, were abandoned in 1944; i.e., Fleenor and Patoka in Gibson County, Grafton and Rapture in Posey County, Vaughn in Vandei-bwgh County and Millersburgh, Warrick County.

Jan 1, 1945

By Jorge Blanco, Joaquin Gotor, Enrique Delgado, Carlos Frias

Since 2009 Cobre las Cruces (CLC) has successfully operated a sustainable mining business near Seville, Spain, applying the most advanced hydrometallurgical technologies to process secondary copper sulphide ores through atmospheric leaching in ferric sulphate media and using oxygen sparging in a cascade of ten reactors. In comparison to conventional copper smelters, the CLC hydrometallurgical process does not generate SO2 gas, airborne emissions or slags. The copper ore is ground and sent directly to atmospheric leaching reactors; flotation is not required, and consequently, copper extraction is maximized at 93-95%, while producing 72,000 t/y copper cathodes of the highest purity (99.999 wt.% Cu, Grade A). Reserves for the CLC deposit were estimated at 16 million tonnes of ore averaging over 6 wt.% Cu and containing principally a chalcocite mineralization. Other copper bearing species include digenite, covellite, chalcopyrite, bornite and enargite. Pyrite represents over 70 wt.% of the ore. In the CLC leaching process, chalcocite reacts with ferric sulphate at approximately 90 ºC and copper is released into solution while ferric ions are reduced to ferrous ions. The ferric sulphate leachant is regenerated continuously by oxygen injection and consumes sulphuric acid. It is remarked that pyrite plays a crucial role to yield high copper leaching rates. When pyrite is oxidized, a small proportion of iron is co-leached and some sulphuric acid is generated. The CLC leaching technology has been designed to allow a certain level of pyrite oxidation, which is positive in many ways: (i) to maintain a Fe/Cu ratio in solution; (ii) to facilitate Fe(II) oxidation; (iii) to produce a high redox potential; and (iv) to counterbalance a bleed solution that removes some iron. Moreover, galvanic interaction between pyrite (cathode) and chalcocite (anode) can substantially increase atmospheric leaching kinetics and efficiency (copper recovery).

Jan 1, 2016

By Shaun Booth

Automating Delay Reporting to Deliver Effective Maintenance Corporate Background: Technology Company: Matrikon Inc. Global software and service provider of Information Technology and Control Solutions that deliver Business Results. Case Study Facility: Bulga Coal Handling and Preparation Plant <CHPP> Australian site, part of Xstrata, an international Swiss natural resources group. Technology: ProcessMORe ? Missed Opportunity Reporting (Delay Reporting). Matrikon?s technology implemented at many facilities, to deliver effective maintenance Matrikon International Inc. Global software and service provider of Industrial Decision Support, maintenance and control solutions, with universal connectivity to existing systems and work processes. ? 1999 ? 100 employees ? 2003 ? 450 employees ? Our offices: 20 offices worldwide: ? Quebec, Toronto, Edmonton, Calgary, Ft.McMurray, Vancouver ? U.S. ? Australia (formerly Hunter Controls)

May 1, 2003

By R. E. Robinson

A novel variation of the GYPCIX process for the treatment of the acid mine effluent water from Grootvlei is described, in which a number of valuable by products can be obtained and the product water can be used for a variety of different purposes. A conceptual case study is presented in which the important cost parameters are described and certain critical path activities are indicated in order to derive a Return on Investment evaluation according to methods previously published. The study indicates that the treatment costs can be dramatically reduced, provided that proper utilization of the by products is taken into account. There are many possible uses for the water. However, by far the most advantageous contribution to the RDP and the best return on capital is derived if the water is used to establish small-lot farming activities providing work opportunities for thousands of people and contributing several hundred million Rands to the GDP. Vastly improved social conditions will be generated in an area of Gauteng that is in danger of rapid deterioration and a contribution will be made to maintaining mining activities in this area. The environmental impact is positive.

Jan 1, 1998

By J. K. Qu

As one of the key inorganic chemical industries, the chromate chemical industry has spawned extensively public concerns due to the resulted environmental pollution. The cleaner production technology for chromium compounds bases on sub-molten salt medium developed by the Institute of Process Engineering, Chinese Academy of Sciences has greatly decreased the reaction temperature and energy consumption, significantly in-creased the utilization ratio of the chromium element, and successfully achieved the comprehensive utilization of chromite resources and zero emission of chromium-containing residue. The separation process of production is the most important components in the cleaner technology. In this work, we studied two parts: the first is the removal of SiO2, Al3+ from the system and the recycling utilization of alkali metal medium through adding Ca(OH)2 and CaO; the second is to get more pure K2CrO4 crystalloid and remove K2CO3 from KOH solution through evaporation to prepare raw material for manufacturing Cr2O3 and get 50%(wt) KOH. The results obtained show that Ca(OH)2 can remove Al3+ more than CaO and has lower caustic ratio than CaO when they were added 110% of theoretic quantity. The optimal pure K2CrO4(96%) can be gained at 45 Celsius degree in 30% KOH solution and K2CO3 in 50% KOH solution could be decreased to 3.5%(wt) at 40 Celsius degree. And then K2CO3 can be causticized with adding Ca(OH)2 to recycle potassium alkali. The impure material can be re-moved and suitable raw material for manufacturing Cr2O3 can be gotten and reaction medium can be also recycled in this process technology, realizing cleaner production effectively.

Jan 1, 2014

By B. J. Madden

Over 206 million tons of hard coal were mined in South African collieries in 1996. Some 132.5 millions tons came from underground operations and approximately 120 million tons came from bord-and-pillar workings resulting in between 100 000 and 150 000pillars being formed. Coal pillar design remains a significant feature of South African mining. This paper reviews South African coal pillar design procedures in the light of 90 pillar collapses that have occurred since 1904. It shows that, while the current pillar strength formula is still valid within the original empirical range of Salamon1,cognisance must be taken of local conditions. Current South African coal pillar research is attempting to account for the variations in local conditions with the emphasis on the effect of discontinuities and pillar deterioration. It is suggested that a more holistic approach to pillar design be adopted to include a design methodology that examines the stability of the roof, pillar and floor of the underground workings. Using this approach, deviations from the empirical database used by Salamon and Munro will be incorporated into the design methodology resulting in more stable underground workings.

Jan 1, 1998

By J. S. Kirkaldy, G. R. Purdy

THE formation of ferrite in supersaturated aus-tenite has been the subject of considerable speculation and investigation. Aaronson has recently reviewed the data pertinent to this reaction.&apos; Since these data in all cases refer to ternary or high-order alloys it is not possible to put them to the test of simple binary diffusion formalism. It has not, therefore, been possible to make a certain statement as to the controlling mechanisms in the process. An assessment of the difficulties inherent in the conventional statistical metallographic approach suggested that a study of the problem by means of a macroscopic two-phase diffusion couple might contribute useful information. Accordingly, such a couple was synthesized, and the rate of motion of a ferrite-austenite phase boundary (the growth of an austenite layer at the expense of a ferrite layer) was determined. Wagner originally produced a diffusion solution applicable to the motion of a planar phase interface in a binary diffusion couple, assuming local equilibrium throughout the diffusion zone. This solution, which is stated free of typographical error* in Ref. where a is the position of the interface in A space (A = x/fi), C; and CL1 are the equilibrium inter-facial concentrations in phases I and 11, C: and C*1 are the initial bulk concentrations in phases I and 11, and & and are diffusion coefficients (assumed constant). If a diffusion couple consisting of homogeneous layers of ferrite and austenite in equilibrium is raised to a higher temperature, the austenite layer will grow at the expense of the ferrite. Provided that the thickness of the ferrite layer is much less than the diffusion length of carbon in ferrite, we can set , so that Wagner&apos;s solution reduces to

Jan 1, 1963

By O. C. Blade

Diesel fuel is being used in greater volume than ever before in the United States. During 1950 railroads used 43 percent of the total volume of Diesel fuel sold, smelters, mines, and manufacturing plants used about 13 percent, highway vehicles such as trucks and busses, and equipment such as tractors and bulldozers accounted for approximately 20 percent, about 12 percent was used by water craft, and the remaining 12 percent by gas and electric utilities, the military forces, and oil companies. These figures were calculated from data issued by the Bureau of Mines. 2/ Comparable figures for 1951 and for 1952 to date are not available, but recent information indicates that well over 11,000,000 barrels of Diesel fuel per month are produced by the country&apos;s refineries. 3/ More information on this increasingly important type of engine fuel is needed by the petroleum industry, engine manufacturers, and consumers, particularly on the grades and qualities of the Diesel fuels being marketed. To supply this information the American Petroleum Institute and the Bureau of Mines, United States Department of the Interior, under cooperative agreement, are conducting annual surveys of Diesel fuel oil produced in refineries in this country.

Jan 1, 1952

By C. R. Wohrman

A melt of pure electrolytic iron with about 0.4 per cent. sulfur and 7 per cent. manganese was prepared in connection with a study of inclusions in iron. The alloy darkened rapidly when etched with a 10 per cent, alcoholic solution of nitric acid, and microscopic examination revealed the presence of a semimartensitic, semi-Widmanstättian structure (Figs. 1 and 2) closely resembling the structures found by Benedicks in his artificially prepared "meteoric iron."&apos; The structures found by Benedicks were readily explained by the presence in his alloy of the two well-known iron-nickel solid solutions, taenite and kamacite, and of their eutectoid (?) aggregate, plessite. By analogy, one would infer the existence of similar phases in the iron-manganese alloy just described, such an inference being strengthened by the similarity displayed in many ways by nickel and manganese in their effects on iron. Iron-manganese Alloys are Regarded as Homogeneous Heterogeneity of iron-manganese alloys has not been recognized heretofore, judging from the data of standard metallographic books and those of original papers. In fact, iron and manganese are quite generally regarded as completely miscible in the solid state. Dr. Rosenhain,2 for example, writes: Alloys of group (a), of which those of gold-silver, iron-manganese, and copper-nickel are examples, when allowed to crystallize sufficiently slowly to attain their condition of final equilibrium, present a microstructure exactly similar to that of a pure metal—the homogeneous character of the molten solution is in that case so completely maintained that the microscope cannot detect the presence of any second constituent. Guillet and Portevin3 refer to the iron-manganese system as an example of the "case of metals completely miscible in the solid state."

By Adrian M. Keller

Borehole televiewers are downhole inspection devices available for high-resolution imaging of a borehole wall following rock coring. Borehole televiewers should be considered by geotechnical engineers and geologists as a supplemental way of investigating rock for deep foundations. The optical televiewer (OTV) produces a digital optical image and the acoustic televiewer (ATV) utilizes reflected acoustic waves to produce images of the borehole walls. These devices can be utilized to examine soft or fractured zones in the rock mass, solution features, open joints or other voids not observable from traditional rock coring techniques. These devices along with computer post-processing can determine the strike and dip of joints, bedding planes, shear surfaces, or other structural features, eliminating the need for expensive oriented cores or manned downhole logging. An acoustic televiewer was utilized in the Fall of 2008 during the investigation phase for the I-70 New Mississippi River Bridge (I-70 MRB) in St. Louis, Missouri. Voids and fractures in the upper portion of the rock were described by prior consultants. Further investigation of these features was necessary to evaluate deep foundation options to support the main towers. Ten borings were drilled from a barge in the river at the two main tower pier locations. An ATV was utilized in each of the ten borings to produce images of the rock mass in the borehole and allow further investigation of the voids. Voids interpreted as solution features were readily identified in the ATV logs in multiple borings and at similar elevations, suggesting connectivity. Measurements of the voids? width, location in the borehole and orientation allowed a more thorough understanding of the potential impact the solution features may have on the planned deep foundations. An extensive grouting program was eliminated based on the ATV results.

Jan 1, 2010

By Robert S. Schecter, Mark P. Walsh, Michael J. Humenick

In recent years in situ leach mining has emerged as a viable technology for the recovery of uranium from strata in South Texas which contain relatively low concentrations of uranium ore. Because the ore bodies lie within ground-water aquifers, a significant determinant in the economics is the requirement that such aquifers be protected from contamination. Since ammonia is one of the constituents of the leach solutions now being field tested, one environmental problem to be resolved is the removal of ammonia at the end of mining. A second related question is the fate of the ammonia which is not removed by the restoration procedure. This paper considers the displacement and migration of ammonium in a flowing electrolyte with concomitant ion exchange. The ion exchange is an important feature since, during the solution mining phase, ammonium saturates the mineral exchange sites and must be removed from these sites. A mathematical model is used to simulate this process and the model is tested against the results of laborator.y experiments. It is found that the simulations are adequate if an appropriate selection of parameters is made. The model is then used to investigate the effect of cation composition and concentration of the restoration medium as well as dispersion on the overall effectiveness of the process. It is concluded that increasing the concentration of monovalent ions in a solution containing a mixture of both monovalent and divalent ions decreases the adsorption selectivity of the divalent ions with respect to all monovalent ions including ammonium. Thus increasing the ionic concentration of a restoration fluid by increasing the concentration of a nonselectively adsorbed (with respect to ammonium) ion may have a very limited benefit.

Jan 1, 1979