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By C. Allen, V. Hensel, J. S. Stachulak

"Vale has been actively evaluating new technologies to curtail diesel emissions. This paper discusses the selection, installation, operation, and evaluation of the MANN+HUMMEL SMF®-AR diesel particulate filter system to reduce diesel particulate matter emissions in underground mines. The system uses a sintered metal filter element, an iron fuel-borne catalyst with an onboard dosing system, an electric heater that uses onboard power, and a sensor-based control unit. More than 6,000 h of testing demonstrated that the system represents a breakthrough in the successful control of soot emission from light-duty vehicles with differing soot emission levels, exhaust temperatures, and duty cycles.RÉSUMÉ La compagnie Vale évalue activement de nouvelles technologies pour réduire les émissions de diesel. Le présent article discute du choix, de l’installation, du fonctionnement et de l’évaluation du système MANN+HUMMEL SMFMD-AR de filtrage des particules de diesel pour réduire les émissions de particules de diesel dans les mines souterraines. Le système utilise un élément filtrant en métal fritté, un catalyseur à base de fer dans le carburant avec un système de dosage intégré, un élément de chauffage électrique qui utilise l’alimentation incorporée et une unité de contrôle avec un capteur. Plus de 6 000 heures d’essais ont démontré que le système représente une avancée pour réussir à contrôler les émissions de suie des véhicules légers avec différents niveaux d’émission de suie, différentes températures d’échappement et différents cycles opératoires."

Jan 1, 2015

By R. Boom

Corus Umuiden, formerly Hoogovens, was the first steel plant in Europe after Voest to introduce oxygen steelmaking. In the decision-making process contacts with Dofasco in Canada about the production of formability steel grades were crucial. In developing oxygen (LD-) steelmaking high liquid steel output rates had to be combined with accurate process control. For ingot casting static models with input control and sampling during interrupted blowing were sufficient to deliver liquid steel within the required carbon, phosphorus, sulphur and temperature windows. Computers were introduced to perform the complicated charge calculations. Continuous casting called for strict control of composition and temperature at process end point and made predictable timing crucial. Dynamic control was introduced based upon sub lance measurements and waste gas analysis. Reliable disposable measurement sensors were developed in a concerted international action. Dissolved oxygen at blow end deteriorated the quality of low carbon aluminium killed steel grades. Blowing gases through the converter bottom improved process kinetics, resulting in lower carbon-oxygen products, yield increase and better phosphorus removal and generated new families of hybrid blowing processes. Introduction of secondary metallurgy facilities such as argon stirring stations, vacuum degassers and ladle furnaces relieved the demands for strict BOF end point control. Desulphurisation of hot metal became standard practice. In regions with scrap shortage hot metal desiliconisation followed by dephosphorisation, was introduced in the blast furnace cast house and hot metal transfer ladles. Later redundant converter vessels were used for pre-treatment, resulting in a two-stage process. The fundamentals of oxygen steelmaking are described and a vision on the future is presented.

Jan 1, 2004

By G. W. Evatt

This paper presents the scientific framework underpinning the Resource Valuation and Optimisation Model (RVOM). The RVOM is a Real Options software package, which helps mine owners optimally plan their operations, understand their project risks, and make defensible valuations. This is achieved in the presence of both financial and physical uncertainty. The three key outputs from the RVOM are: Valuation, Optimal Decision and Probability of Decision, where a decision can include any combination of: normal operation, expanded operation, care and maintenance, and abandonment (and variants thereof). This paper presents a clear example of the RVOMs usage to a case-study gold mine.

Jan 1, 2011

By A. Rodriguez-Prado

"Magnetic fields affect the growth of cultured cells and plants; however, limited information exists about their effects on vegetation performing environmental remediation. Constructed wetland mesocosms treating hexavalent chromium (Cr(VI)) wastewater exposed to low-intensity magnetic fields (60 Hz, 56.5 × 10-6 Tesla) produced 100% more biomass than the unexposed control. Nonetheless, they removed only 43 ± 27% of Cr(VI), compared to 60 ± 21% for the control. A Cr(VI) reduction expression was developed as a function of the magnetic field. The design and operation of constructed wetlands to treat mining wastewater can be corrected for magnetic field effects.RÉSUMÉ Les champs magnétiques affectent la croissance des cellules et des plantes cultivées; toutefois, il existe peu d’information quant à leurs effets sur la végétation utilisée à des fins d’assainissement environnementale. Les mésocosmes des marais artificiels traitant des eaux usées, contenant du chrome hexavalent (Cr(VI)), exposés à des champs magnétiques de faible intensité (60 Hz, 56,5 × 10-6 Tesla) ont produit 100 % plus de biomasse que le contrôle non exposé. Néanmoins, ils n’ont enlevé que 43 ± 27 % du Cr(VI), comparativement à 60 ± 21 % pour le contrôle. Une expression de réduction du Cr(VI) a été développée en tant que fonction du champ magnétique. La conception et l’exploitation de marais artificiels pour traiter les eaux usées des mines peuvent être adaptées pour tenir compte des effets des champs magnétiques."

Jan 1, 2015

By M. Al-Khawaja, F. Hassani, F. Mucciardi, N. Razavinia

"In today’s economy many industries are becoming aware of the need to recover some of the waste heat they create. Industrial processes release, on a global scale, over 100 tera-Joules (i.e. 1014 J) of waste heat annually. The recovery of waste heat can lead to a reduction of greenhouse gas emissions and it can also provide a financial benefit which can be obtained by converting some of this excess heat to electricity. At McGill, a research program has been initiated so that low grade waste heat (temperature between 100ºC and 300oC) from process off-gases found in pyro-metallurgical industries is captured and concentrated by using heat pipes and then converted to electricity by a mechanical engine. This paper illustrates the 3 C’s process (capture, concentrate and convert waste heat to electricity). It also provides some preliminary experimental data. INTRODUCTIONThe problematic climate change caused by the use of fossil fuels, the rapid depletion of global reserves and the catastrophic consequences of nuclear power generation call for renewable and safe, resources of energy, for both man and the environment. Extensive researches in the production of energy from renewable sources and improvements in efficiency of current technologies can help us to reverse this trend.The greatest advantages of using renewable energies are that they don’t deplete and they also contribute to a green environment. On the other hand the disadvantage of using these resources is that the energy available from renewable sources is much less concentrated than that provided by fossil fuels and nuclear energy. This makes renewable energy less attractive for large scale industrial uses in most cases. A key target for society for the 21st century is the production of energy from renewable sources at a cost that is competitive with fossil fuels. Fossil fuels represent a concentrated form of energy; usually it is referred to as high grade energy. Nonetheless, there is a vast supply of alternative energy. The sun, wind, water and biomass were the first to be explored. While these are all valid options that warrant concerted efforts and large investments, there is another source of energy that typically is produced by manufacturing industries. This energy is often referred to as low grade waste heat. Most of this energy is simply vented to the environment through the stream of off-gases. In the future it will be necessary to capture and convert some of the low grade heat to a valuable form such as electricity if we are to improve on the efficiency of energy usage."

Jan 1, 2012

By J. Paraszczak

ABSTRACT Diesel-powered loaders are a pillar of modern underground metal mining. As these mines are getting deeper and hotter and the emission regulations stricter, ventilation costs are soaring, affecting production cost. Also, the cost of diesel fuel is expected to rise. These may make the use of diesel engines more problematic. Electric load-haul-dump machines (LHDs) are an interesting alternative. This paper compares features and performance of diesel and electric, cable-powered LHDs. It overviews equipment offerings, and compares, analyzes and discusses technical parameters, operational problems and cost issues. The paper gives some conclusions about electric LHD applicability and performance, indicates possible applications, and suggests further research work.

Jan 1, 2013

By J. Defreyne

CESL has developed a proprietary hydrometallurgical process for base metal concentrates, notably those of copper and nickel. The process is based on pressure oxidation (PO) of the sulphide minerals, which is done at elevated temperatures in mixed sulphate-chloride liquor at about pH 2 ? 3. The process achieves maximum oxidation of the metals whilst minimizing sulphur oxidation to sulphate. Almost all base metal sulphide minerals are efficiently treated under these conditions. In the case of copper minerals, pressure oxidation does not generally put the copper into solution, because of the relatively high pH prevailing in this process. Therefore, PO is followed by an acidic leaching stage, which specifically aims at maximum copper dissolution with minimal leaching of iron. The overall copper recovery is largely determined by the efficiency of this stage. The process has low capital and operating costs, partly because there is minimal use of acid or neutralizing agents for iron dissolution or precipitation, respectively; this is achieved by minimizing iron leaching during both the oxidation and leaching stages. Iron sulphides in the feed concentrate deport almost entirely to the solid leach residue as hematite, which has superior handling characteristics for filtering and washing. Iron minerals play a key role in the process, with pyrrhotite and pyrite having very different responses to the oxidation process. Acid management for the whole process is affected by the iron mineralogy, and the flowsheet is therefore tuned to the specific concentrate.

Jan 1, 2006

By E. Poiate, P. R. Cabral, A. V. N. Santos, P. V. M. Costa, C. S. Amaral, A. M. Costa

This paper discusses the design of underground salt caverns, opened by solution mining, for the production of brine and storage of natural gas under high pressures. The caverns are located in the salt basin in Maceio City, Alagoas State, at the northeast region of Brazil. Special attention is given to the geomechanical structural design of the caverns using computer codes specially developed for the simulation of excavations in salt rock formations, considering validated constitutive creep laws under different initial stress states and temperatures. The behavior of sedimentary rocks intercalations presented in the salt layer is simulated using elastic-plastic models. The excavation of the caverns by solution mining is also simulated starting from a geostatic initial equilibrium state of stresses, with a unique formulation only implemented in these computer codes, without the need of the application of boundary stresses to the model in order to develop the initial state of stresses. These computer codes have being used in the design of several clusters of caverns for brine production used as raw material of Poly Vinyl Chloride (PVC) of the Chemical Industryin Brazil. These computer codes and methodology were also applied to the design of the underground conventional potash mine in the state of Sergipe, overlying tachyhydrite and carnallite with very high creep strain rate. They have also been used in the design of the pre-salt oil wells through thick layers of stratified salt rock in Santos Basin, for the exploration and production of the pre-salt reservoirs in Brazil. The constitutive creep equations implemented in the codes are based on a double mechanism creep law. The creep constants adopted in the simulation are taken from a previous investigation carried out on an experimental panel of the potash mine, considering the stratified geology with different salt rocks of the basin where the mine is located. These constants were also obtained by lab tests under different confined and differential stresses and temperatures.

Jan 1, 2015

By A. M. Ramadan

The composition of phosphate rocks, mainly used in manufacturing fertilizers, varies among deposits; therefore, phosphate rocks from different sources are expected to behave differently in acidulation processes. This paper examines the effect of preconcentration of phosphate ore from El-Sebaiya East, Egypt, using flotation on uranium leaching. A high-grade ore sample (27.3% P2O5, 168 mg/kg U) supplied by the Al-Nasr Mining Company, was subjected to reverse single-stage flotation to separate carbonate from the phosphate sample. Subsequently, P2O5 and U concentrations were 32.2% (92.1% recovery) and 225 mg/kg, respectively. After the leach process, the U concentration in the liquor was 319 mg/L.

Jan 1, 2014

By G. W. Smith

"The adsorption of dehydroabietylamine acetate on quartz, hematite, rutile and baddeleyite has been deter-mined for concentrations ranging from 0.3 to 5,600 µ. moles/I and for pH values ranging from 2.5 to 10.5.The surface tension, UV and IR spectra, equivalent conductance and ion concentrations for dehydroabiety lamine acetate solutions have been determined.Contact-angle and flotability studies have established that good collection may be obtained with this amine but that selectivity depends on the suitable use of depressants for some of the minerals."

Jan 1, 1971

By M. Boher, J. Lehmann, M. C. Kaerlé

"In the production of high quality steel, the understanding of the interactions between liquid steel and refractories and of their effect on steel purity and cleanness are becoming more and more important.An experimental study has been per-formed in order to estimate the importance of the reaction between a MgO-based tundish refractory and an Al-killed steel. The results show a pollution of the liquid steel:•the silicon content of the liquid steel increases due to the reduction of the silica of the refractory by the aluminum contained in the steel; and•a reoxidation of the steel occurs and the formation of an oxide layer on the refracto-ry, mainly composed of spinel crystals and of Ca-aluminates is observed.The transfer mechanisms of the various elements are analyzed."

Jan 1, 1997

By Chris M. Healey

"Abstract- The Jasper Gold mine in northern Saskatchewan produced a total mill feed of 140 127 tonnes at an average grade of 19.0 g/t Au. Both diamond drilling and chip samples from under­ ground workings returned extremely high values, up to 12 851 g/t (375 oz/I) Au over 0.10 meter from a chip sample. In the presence of such extremely high grades, the accurate estimation of reserves is a major problem.ln the first part of this study, production data from the mine were used to evaluate the results of a variety of reserve estimation techniques in this environment. In two out of three cases studied, indicator kriging with assays cut to 342.9 g/t (10 oz/I) gave extremely good results. In the third case, however , indicator kriging gave unacceptable results. Instead, lognormal kriging of uncut data gave the best results.Secondly, from the same database, a number of drill-hole spacings were simulated, and reserves estimated from the simulations. As may be expected, the results of this analysis show increasingly better results with tighter drill-hole spacing. However, even with a 5 m by 5 m spacing the variation from actual grade was quite large. This is not a systematic under- or over-estimation of grade, rather a random scatter of results .The results of this study show very clearly the problems of deriving good estimates of reserves when extremely high-grade samples are encountered. There is a high degree of randomness to this database, so reserve estimation in this situation will remain a high-risk operation."

Jan 1, 1993

By A. M. Bell

General Summary THIS paper attempts to describe in a preliminary and general manner the nature of certain copper discoveries now being developed by Gaspe Copper Mines, Limited, in Holland township, in the interior of the Gaspe peninsula. Some copper mineralization appears to have been known here at the time of the earliest French explorations, was rediscovered in 1921, and has been under intermittent development by Noranda Mines since 1938. In the last two years discoveries have enhanced the picture so that the deposit now promises to develop into one of the important Canadian copper producers. As ideas are constantly changing with continuing development, any picture given now is very partial and tentative and must be subject to future revision. The nature of these copper occurrences differs from others known in eastern America. In many respects they have unique features but they are most closely akin to some copper deposits found away from the intrusive rocks in the porphyry copper districts of the western United States. The most important orebodies are replacement deposits in a limestone horizon in which the ore gangue is converted to skarn. These lie at considerable distances from any known intrusive but seem to have been derived from a buried stock of granite that intrudes the sedimentary rocks of Lower Devonian age. This intrusive has produced alteration effects in the overlying rocks that may afford a key to locating other ore areas in the Peninsula.

Jan 1, 1951

By Tong Guan, Guangqin Fu, Lihong Deng, Yuanlin Chen, Xiaotong Zhou

"In natural world, some kinds of scheelite minerals are rich in molybdenum. Molybdenum exists in the crystal lattice of scheelite in the form of isomorphism, and the content of MoO3 varies from 2% to 10%. As a result, the flotability of seyrigite (scheelite with molybdenum) turns to be weaker. One seyrigite mine, which has been built for 3 years,still could not produce qualified seyrigite concentrate due to the weak flotability of seyrigite (Mo-bearing scheelite) in raw ore. In our experimental research, through adopting new seyrigite collector TA-3 and advanced mineral processing technology, the seyrigite concentrate with a grade of 65.62% WO3 at a recovery of 87.47% was obtained for the raw ore containing 0.19% WO3 and 0.074% Mo. By applying the new technical achievement, for the raw ore containing 0.272% WO3, the seyrigite concentrate assaying 68.03% WO3 with a recovery of 77.56% was obtained in industrial production.INTRODUCTIONIn natural world, some kinds of scheelite minerals are rich in molybdenum. Molybdenum exists in the crystal lattice of scheelite in the form of isomorphism, and the scheelite is changed to be seyrigite (Ca[(W,Mo)O4]) (Ma, Bian, & Wang, 2013). The content of MoO3 in seyrigite varies from 2% to 10% usually, the content of MoO3 in some of the seyrigite even reaches 34%. The flotability of seyrigite is weak (Zhang, 2007), and the seyrigite is difficult to be recovered by flotation with common collectors and regulators. One scheelite mine in Anhui China, which is a skarn type seyrigite mine, has not produced qualified concentrate yet since 3 years it has been built due to the limit of beneficiation technology. Therefore, it is necessary to conduct research on the collectors with high efficiency and developing advanced processing flow for this kind of ore."

Jan 1, 2016

By K. V. Gow, F. A. Jerabek

"THE NOVA SCOTIA TECHNICAL COLLEGE has been granting degrees in mining engineering since 1909. The college was established in 1907 to provide the final two years of the undergraduate program in engineering the earlier years of which are given at several small universities scattered around the Atlantic Provinces. Since the beginning of the program, 251 Bachelor of Engineering degrees have been awarded in mining engineering. Although the average class size has been small, increases in enrolment in the past few years have resulted in Nova Scotia Technical College being the second largest mining department in Canada, based on the number of graduates per year. This year 18 students received B.Eng. degrees, and next year 17 will graduate.In 1968, it was necessary to make a decision on whether or not to abandon, for economic reasons, the program in mining engineering. For several years enrolment had been very low and resignations among the mining engineering staff created a situation in which the program could easily have been dropped. However, it was decided to continue mining engineering, as it was the only such program in the Atlantic Provinces. New staff members with many years of practical experience in the mineral industry, not only in Canada but in the U.S.A., South America, Africa and the U.K., joined our department. At the same time the enrolment in mining engineering began to increase significantly."

Jan 1, 1972

By J. J. Denny

IN a preliminary paper (1) it was shown that the addition of small quantities of metallic aluminium powder almost completely inhibited the solubility of siliceous material in the beaker. Six rabbits exposed to quartz dust for six months all showed well developed silicosis. Seven rabbits exposed to quartz dust plus 1 per cent metallic aluminium powder for the same period did not develop silicosis. At that time, we were not in a position to state either the manner in which metallic aluminium reduced the solubility of siliceous material, or, from the animal experiments, whether the aluminium was acting locally or systemically, or for what period after the cessation of dusting it would continue to act. This paper reports the further progress of this investigation. CHEMICAL EXPERIMENTATION The technical details pertaining to the various substances used in the experiments are given in an appendix which is on deposit with the American Documentation Institute, Washington, D.C. For lack of space, it is not printed here. The term 'solubility' is used to indicate the concentration of silica in the solution under the conditions as noted, determined colorimetrically (2), and expressed as parts per million (p.p.m.). The term 'reduction in solubility' indicates the difference between the solubility of the .silica in the presence of the aluminium powder and its solubility in the absence of aluminium powder. It will be noted that the solubility figures for different samples of quartz with no added aluminium vary considerably. The figures do not refer to an equilibrium solubility of silica but to the actual amount of silica dissolved from a given sample in a given time at a given temperature. In view of the fact that quartz dissolves extremely slowly, it is evident that the actual figures in any case will depend upon the surface exposed, i.e., fineness of grinding of the different samples.

Jan 1, 1939

The current mining operations at Newmont Boddington Gold Mine (NBG) commenced in 2008, and commissioning of the processing plant started in the latter half of 2009. Metso Process Technology and Innovation were engaged to assist NBG with commissioning and project ramp-up through the implementation of a comprehensive ?Mine-to-Mill? Process Integration and Optimisation project. This methodology entailed extensive data collection which included drill and blast audits, ore characterisation, comprehensive comminution circuit surveys and review of operational data to assess the limitations within the current mining and processing operations. The results of these investigations have been used to define the operating base line of both the mining and processing areas and identify improvement opportunities. The use of modelling and simulations, utilising actual production data, has allowed for multiple scenarios to be evaluated, minimising the requirement for actual trials and thereby minimising impact on the operation. Improvements implemented to date include: the introduction of routine rock strength measurement for inclusion in block models, modifications to blast design improving ROM fragmentation and downstream comminution process performance, and changes to improve performance of secondary crushing and grinding circuits. Close cooperation between the mine and plant personnel is playing a significant role in overcoming the challenges presented to this operation and further improvements are targeted for the second full year of process plant operation.

Jan 1, 2012

By Gordon Jackson

"There are two accomplishments of air and gas drilling: a new series of economic and mechanical challenges; and, acceptance as a standard drilling and completion tool.The new challenges are related to the concept of using a gaseous circulating medium in drilling for oil or gas. For purposes of discussion, a two part division has been made: the challenge of fluid invasion control and that of equipment and tools. Great strides have been made in the development of materials and techniques to combat formation fluid invasion. Chemicals and the ""mist drilling"" technique, now in use, have the versatility to cope with a wide range of downhole fluid entry conditions.Equipment and tools have been developed to meet the challenges of better, more economic drilling and completion possible with a gaseous circulating fluid. Economic and operational challenges remain.Acceptance of air and gas drilling as a normal operating tool was reached with difficulty. It is now established as a means of reducing costs in exploratory and develop-mental well drilling, exemplified in a recent study of 226 wells covering 419,407 feet of hole in the United States. Air reached the projected depth in 85 per cent of the operations, although formation water was encountered in 48.7 per cent of the holes. Slim hole bit performance and cost all compared for overall bit averages as part of analysis."

Jan 1, 1961

By Ata Akcil, Z. B. Karshigina, Ye. G. Bochevskaya, Z. S. Abisheva

"Phosphorus slag is the most heavy-tonnage waste of yellow phosphorus production, which is stored in the dump fields for many years creating ecological problems in the regions. Despite of the actions taken to utilize the slags, most of them remain in the slag disposal area. One of the relevant and priority directions is rare-earth metals production (REMs), presence of which in the phosphorus slags allows considering the latter as an acceptable raw material source. Phosphorus slags contain about 30–40 wt% of silicon dioxide, therefore they can serve as a source of production of precipitated silicon dioxide highly required in different industries.The purpose of this work is the most complete REMs recovery in the solution while leaching and subsequent processing of siliceous cake. The work shows results of researches on establishment of the chemical and phase compositions of phosphorus slags, determination of the forms of presence therein of REMs compounds, processes of phosphorus slag leaching by nitric acid and processing of produced siliceous cake by NaOH solution.Based on the data of the instrumental and chemical methods of phosphorus slag analysis, it was established that it consists of pseudowollastonite a-CaSiO3 for 90–92%. It was found out that REMs are present in it in the form of carbonate apatite Ca10(PO4)6CO3 or rare earth apatite, and La2S3 compound inclusions.Optimum parameters of phosphorus slag leaching process were selected: HNO3 concentration 7- 7.5 mol/L; L/S ratio = 2.6–3 mL/g; temperature – 50–80o?; duration – 1 h; pulp stirring – 500 rpm. Recovery of SREMs, CaO, Al2O3 and Fe2O3 into the solution were achieved at 98.0, 99.1, 99.0 and 18.8%, respectively. Presence of 10 elements of the rare earths group in the phosphorus slag was established. It was found out that recovery of almost all REMs is within ~92–99%, except for Sc and Lu – ~39% and ~28%, respectively.For the purpose of optimization of siliceous cake leaching by NaOH solution, influence of some physical and chemical parameters was studied: N?O? concentration, L/S ratio, temperature, and duration. Results of the experimental data will serve as a basis for development of the technology of complex processing of the technological waste of phosphorus industry with production of REMs concentrate and precipitated silicon dioxide."

Jan 1, 2016

By G. Deschênes

Located in North West Tanzania, Buzwagi is an underground narrow-vein gold mine owned by Barrick Gold. The plant was commissioned in 2000. The reserves are estimated to be more than 25 years. The ore, containing gold, silver and copper mineralization in sulphides, is processed at 3,300 tpd. This paper presents the results of an investigation to determine the performance of an ammonia-cyanide leaching approach to recover gold from two samples. Coarse gold was recovered by gravity prior to leaching. The gravity tailings had the following composition; 1.97 g/t Au and 0.31% copper for the medium cyanide soluble copper (MCSC) sample and 2.80 g/t Au and 0.53% Cu for the high cyanide soluble copper (HCSC) sample. Experiments were conducted for 72 hours in stirred tank reactors with monitoring and control of parameters. The straight cyanidation produced gold extractions of 76.1% for the MCSC sample and 84.6% for the HCSC sample. Associated cyanide additions were 6.1 kg/t and 11.5 kg/t respectively. The gold extraction of the MCSC sample was improved to 88.8% using 350 ppm NaCN and 700 ppm ammonia. The associated cyanide and ammonia additions were 2.5 kg/t and 1.7 kg/t respectively. For the HCSC sample, 82.5% gold extraction was obtained using 500 ppm NaCN and 600 ppm ammonia. The cyanide addition and ammonia additions were reduced to 3.8 kg/t and 1.0 kg/t respectively. No significant decrease in gold extraction was noticed when the cyanide and ammonia were reduced to 150 ppm and 500 ppm respectively. In the presence of ammonia, a significant amount of cyanide was oxidized to cyanate by the cupric ion. In the absence of ammonia, the formation of copper cyanide was the predominant reaction responsible for consumption of cyanide.

Jan 1, 2012