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By M. Saba

In cyanide leaching procedure, achieving an acceptable efficiency for silver and gold is very time-consuming, thus, enough studies have not been performed for optimization and modeling of this process. The kinetics of cyanide leaching includes two steps: first step comprises a sharp slope while the other has a slight increasing trend. In the present study, in order to reduce the time and cost, the cyanide leaching process of a sulfide silver/gold ore was optimized in the first period. The applied parameters and their ranges are: temperature 20-40 (°C); time 1-8 (hrs); cyanide concentration 1-2 (mole cyanide / mole Cu); the percentage of solid to liquid 1-2 (%) and pH 10-12. For design of experiments fractional factorial 2(5-1) was used. Also four center points were applied to increase the accuracy of the model. In addition, by analysis of variance (ANOVA) the most effective parameters were identified and the optimized condition was determined. A regression model was proposed to describe the effects of independent variables and their interacting role on silver recovery. Results showed that the model was linear for silver and nonlinear for gold. In the gold recovery process, the two important parameters are time and pH with the former being more effective. Due to the existence of cyanide ions in the medium, temperature and cyanide concentration have less influence in the gold recovery process. Solid to liquid ratio, in addition, comprises a slight negative impact on the procedure. This emphasizes the different kinetics of silver/ gold cyanide leaching. Finally, using the optimum condition the amount of silver and gold obtained were 61% and 67% in 8 hours, respectively. While in general conditions, the results were 37% and 54% in 24 hours, respectively. Keywords: cyanide leaching, refractory gold/silver ore, modeling, optimization

Sep 1, 2012

By Nikhil Dhawan, Shrey Agrawal, Ashwini Kumar

The current study investigates sericite clay as an alternative source of potash and alumina. The alumina and potash content in the sericite is approximately 35 and 10%, respectively, compared with 50–55% in bauxite ore. Muscovite and illite phases are stable, and direct leaching is found to be ineffective. Here, planetary ball milling was performed, which provided dissociation of stable phases to relatively reactive phases. The milling led to a five-fold increase in the surface area, resulting in enhanced leaching kinetics even at low acid concentration. The statistical design obtained optimal conditions of 8 h of milling followed by leaching in 1.73 M HCl at 75 °C, yielding 82% alumina extraction in precipitate with 85% purity in γ-alumina form and 63% potassium dissolution in sylvinite phase. The yield of the precipitate was ~65–68%, and the acid leach residue contained primarily silica.

By A. V. Tarasov, V. M. Paretsky

"A mathematical model of the low-temperature (soft) nickel oxide reduction (SNOR) in a tubular kiln has been developed including an equation describing changes in the nickel oxide content of the solid material along the length of the kiln; an equation describing the changes in the content of reagents ensuring nickel reduction (i.e., hydrogen and carbon monoxide) in the gas phase along the kiln length; as well as the temperature along the kiln length. The kinetic relationships used for the development of the model had been determined based on experiments conducted specially for this purpose. Model investigations were conducted to determine the distribution of such parameters along the length of the kiln as the contents of metals oxides in the solids, partial pressure of hydrogen and carbon monoxide, variations of the temperature depending on the SNOR process conditions, including the kiln rotation speed. Based on the data obtained, a simplified regression model of the reducing roasting process was developed.IntroductionAt the SeveroNickel complex (Russia) a technology has been developed and is being introduced on a commercial scale for low-temperature (soft) nickel oxide reduction (SNOR) in tubular kilns.The SNOR process has a number of advantages, the main of which are the higher degree of metallization and higher chemical activity of reduced nickel oxide attributable to the lower fusion of the surface of the grains of reduced material due to lower process temperature (800-1000°C) and improved reducing ability of the gaseous phase. However, the fact that the process is conducted in a gaseous phase sets higher requirements to the consistency of its composition necessitating careful continuous monitoring and control of the main process parameters."

Jan 1, 2001

By A. D. Garman

This paper presents one of a series of digests of foreign mining leg- islation and court decisions which is being repared in advance of a general report relative to the right of American citizens to explore for minerals and to own and operate mines in various foreign countrics. This interpretation of the laws of Panama has been prepared from the best available information in Washington, but is released subject to correction and amplification, if necessary, by the proper American diplomatic and consular officers to who it is being referr ed through the courtesy of the Department of State.

Apr 1, 1930

Reconciliation involves the collection of tonnage, grade (quality) and contained metal (product) data from disparate and hopefully independent sources. Examples are exploration data, production sampling data from blastholes or drawpoints, and process plant data. These data may be compared by means of ratios (factors). The F1 factor usually relates short-term (ore control) model tonnages, grades and metal content to ore reserves depleted. The F2 factor usually relates received-at-mill tonnages, grades and metal content to delivered-to-mill = production tonnages, grade and metal content. The F3 factor is F1 × F2 and enables a comparison of a mineÆs ability to recover the tonnage, grade and metal content estimated in ore reserves. The F1 factor measures the accuracy of orebody knowledge in the ore reserves to the demarcation of ore and waste by ore control (short-term model). The F1 factor may be used to check and calibrate the selectivity of mineral resource models and/or planned dilution assumed in transfer from mineral resources to ore reserves. The F2 factor enables a check on unplanned dilution entering the ore stream between ore control and the mill. Using the factors it is possible to calculate a monetary value on improvements in the accuracy of orebody knowledge, selectivity and the effects of dilution and ore loss. Reconciliation should be an implicit part of the mining process, and reconciliation targets should be a key performance indicator for well-run mines.

Sep 26, 2011

By Wang Xu, Tao Dongping, Zhang Jie, Tao Youjun

Based on the principle of fly ash triboelectrification, the mineral electrical index and testing method are introduced. The electric differences of various mineral components of fly ash are discussed in view of the results of chemical and mineral composition analysis of the fly ash sample acquired from the Xin-wen power plant. The dielectric constant and charge-mass ratio of carbon and ash in the fly ash are determined. The data were then used along with the rotary triboelectrostatic separator (RTS) testing results to investigate the charging characteristic of fly ash particles in different sizes. The results show that the dielectric constant of fly ash with different particle size decreased with the decrease in particle size, which led to a poor electrical conductivity. Thus particle size has an important effect on conductivity. The charges of carbon and ash particles increased with decreasing particle size. The charge-mass ratio of carbon and ash particles of the same size increased with decreasing particle size. This indicates that finer particle size is more favorable for triboelectrification separation from the charging efficiency point of view. The rotary triboelectrostatic fly ash separation tests show that the best decarbonization performance was achieved with particles in the size range of 0.038-0.074mm with which the decarbonization rate and efficiency index reached 38.93% and 120.83% spectively.

Jan 1, 2014

By Thomas G. Tavernaro, Jeffrey A. Schaefer

"The $106 million Olmsted Approach Walls Project, completed in the spring of 2004 by Massman Construction Co., Kansas City, MO, is one phase of a new $1.4 billion Corps of Engineers locks and dam facility located at Mile 964 on the Ohio River, approximately 17 miles (27.4 km) upstream of its mouth at the Mississippi River. When completed, the Olmsted Locks and Dam (Figure 1) facility will replace two aging locks and dams (Locks and Dams 52 & 53) built in the 1920’s, and produce an estimated $600 million annual economic benefit to the nation through reduced lockage time and operation and maintenance costs. PROJECT OVERVIEWThe Olmsted Approach Walls Project consisted of “in-the- wet” construction of four fixed nose pier structures, four floating concrete approach walls, one fixed wall and related underwater excavation, grading and stone placement. Over 12,000 tons (11,000 tonnes) of structural steel and pre-cast concrete elements, up to 335 tons (304 tonnes) in weight, were safely erected during the project.To support these massive structures, the Louisville District of the U.S. Army Corps of Engineers teamed with INCA Engineers, Inc., Bellevue, WA to design thirty seven 10’ (3m) diameter shafts (cast-in-place steel-shell piles) capable of maintaining elastic behavior below ground while resisting barge impact loads, extreme head-on collisions from runaway tows, and environmental forces from river current, wind, and seismic events.The shafts (typically 150’ (45.7m) in length) were founded 100’ (30m) into the riverbed through alluvium, a very consolidated fine sand and clay Cretaceous soil, and finally into a hydrothermally altered rock. Thirty seven shafts were installed under open river conditions at the site, a group of four shafts at each nose pier-pylon location (Figure 2), and 21 at the fixed land wall. Due to difficulty in achieving the required casing tip elevation the team developed a design modification that was successfully implemented for 27 of the shafts.Concurrent with the work at Olmsted, eleven pontoon segments for the four floating approach walls were constructed at a graving yard in Paducah, KY, developed by Massman Construction Company specifically for the project. While the pontoon geometry varied, the pontoons averaged 350’ (107m) in length, 40’ (12.2m) in width and weighed 4,500 tons (4,082 tonnes). The longest of the four walls, at 1,700’ (518m) was comprised of five interconnected pontoons."

Jan 1, 2006

By D. Yadon, P. Lee, W. Kelly, C. Stilwell

Rico is a small town in an old zinc mining district in a mountain valley of southeastern Colorado. Mine waste rock and mill “tailings” remained after over 100 years of mining in the area, leaving associated surface water and groundwater impacts. Atlantic Richfield Company is proposing an innovative approach, which uses lime precipitation and wetland ponds (semi-natural system, also called treatment lagoon in a wetland setting) to treat adit water in the Rico area. Besides using a non-conventional treatment approach, a non-conventional (non-Superfund) regulatory/administrative approach is being proposed. This paper will focus on the water treatment issues and solutions, as well as describing the innovative “watershed” regulatory process.

Jan 1, 2004

By Christopher A. Jacobs

Project managers aim to maximise the NPV of their projects, but don't always appreciate the relationship between mine throughput, project value and the discount rate being used to evaluate their projects. Rate of production or throughput is perhaps one of the most crucial decisions a project manager must make, but if this choice is made arbitrarily, much effort may be spent on a feasibility study that does not optimise project value. The timing of the study in relation to the stage of exploration is examined and simple techniques are presented that project engineers and managers can use to home in on a production rate which will give their project the greatest chance of success.

May 1, 2006

By L. C. George

Addition of an acid waste to an alkaline cyanide waste was investigated for five different combinations of electroplating wastes. At the optimum final pH values of the mixtures, metals and cyanides were almost quantita¬tively precipitated. No evolution of hydrogen cyanide was detected by a few additional processing steps, significant amounts of variable metals were recovered for recycling the waste-plus-Waste step is attractive because no reagents are required, metals arc concentrated, and a relatively harmless effluent that meets most water quality Standards for cyanide content is produced.

Jan 1, 1970

By Elli Miettinen

In Copper Flash Smelting operation disturbances may lead into dust build-up in the gas train and off-gas handling system causing reduced heat recovery efficiency and process availability. Flue dust of a Copper Flash Smelting process heat recovery boiler has been characterized and its thermal conductivity and diffusivity have been determined. Dust accretions consist of several layers possessing varying particle sizes, densities, and thermal properties, with the binding phase usually being sulphate. All the dusts can be regarded as effective thermal insulators with thermal conductivity values of less than 2 W/mK and thermal diffusivity values of less than 0.005 cm2/s. Porosity can be regarded as a fairly good indicator of the thermal transport efficiency of these types of materials, but the material microstructure must also be considered. The results can be used in the dimensioning of metallurgical heat recovery boilers and they also provide accurate input data for process models.

Jan 1, 2009

By P. D. Navarro

The behavior and operability of LIX 1104SM extraction was studied at laboratory scale on the Solvent Extraction at Sb3+, from high concentration sulfuric acid. In order to evaluate the reactant batch tests were made at laboratory scale as well for extraction as for re-extraction of Sb3+. Experiences achieved were: extraction kinetics, temperature effects, selectivity tests and re-extraction selectivity. A extraction kinetics was found, reaching equilibrium in 2 min, high selectivity of Sb3+ extraction in front of Cue , existing As5+ co-extraction and Fe3+ At the re-extraction stage, equilibrium was reached in 3 min, getting high Sb3+ re-extraction efficiency with HCl concentrations within 6 and 8 M. A high selectivity was achieved on Sb3+ re-extraction in front of As+5, existing Fe+5 re-extraction.

Jan 1, 1999

By P. Dhar, H. R. Kota, M. Thornhill

A very high-grade calcite deposit located in northern Norway consists of CaCO3 ore with minor silicate and sulphide impurities. Cationic (Tallow-1,3-diaminopropane, Duomeen T) collector has been used in the purification of calcite by flotation with an aim of achieving calcite concentrate for its use in value-added products in a variety of industries. The feasibility of sulphide flotation from calcite by this cationic collector has been initially judged from Hallimond flotation and zeta potential on pure mineral systems and the results illustrate the removal of sulphide from calcite ore at neutral pH region. The adsorption mechanism of diamine on both the sulphide minerals was found to be the same by zeta potential studies. The variations in zeta potential are in good agreement with the adsorption of diamine molecular and ionic species as a function of pH. FTIR studies also showed the adsorption of diamine species in agreement with the zeta potential and Hallimond flotation results. Furthermore, the removal of sulphide impurities with selective flotation by diamine collector was performed in bench-scale flotation with the calcite ore and the results indeed showed that the calcite concentrate could meet the quality requirements for its use in the paper industry for coating and filler purposes.

By Dan Swidrak, Bill Zietlow

Halfway through a 17,770-ft long stormwater tunnel, an 11-ft diameter TBM encountered a karst void below the Mississippi River in Missouri, resulting in significant inflow. It was decided that the TBM could not safely advance without external intervention. Low-mobility grout was pumped from the surface. A rescue shaft was constructed and a conventional tunnel with spiling support was mined back to the machine. The TBM was removed and a 14-ft diameter TBM equipped with probing drills was relaunched. Probing from the new TBM encountered one additional karst feature but the machine advanced after grouting and successfully completed the tunnel.

Jun 23, 2024

By Renan Bueno Wojciechowski, Yukio Shigaki

The quality of flat rolling process depends highly on multiple factors such as applied forces, materials involved for both strip and rolls, roll geometry and its positioning. To calculate the strip shape, a mathematical/numerical model can be applied, showing the final product and how the equipment behaves when changing some parameters. This is usually a time-consuming task for both user and computer, especially when it involves thin and hard strips. By coupling a quick rolling load calculation method as Bland-Ford and Finite Element Method (FEM) for roll stack deformation, it is possible to create an accurate and user-friendly rolling simulator. This paper presents the improvements done in the 3D FEM/multi-slab method and its actual capabilities by simulating two cases of a 6-High rolling mill. Different analysis in this equipment can be easily done in about 10 minutes by using the developed an electronic spreadsheet program interface and the folder generated with relevant results and logs. An operation manual and a commercial FE program plugins were made to aid construction of a completely new model. The code was created in a modularized way to assist the application of this simulator for other operational conditions.

Oct 1, 2019

By A. M. Anthony, A. Y. Atta, S. S. Magaji, U. Abubakar-Zaria

There are two major gold recovery methods: the hydrometallurgical technique, which employs cyanide solutions, and amalgamation method, which involves mercury (Hg). These methods present considerable health, safety, and environmental concerns. Past applications of alpha-cyclodextrin (α-CD) on gold scraps show that α-CD is not only inexpensive, but is also environmentally friendly. This research work used α-CD to recover gold from gold ores instead of gold scraps. The gold ore was sourced from Shanono gold deposit site Kano State,Nigeria. The gold ore was characterized by fire assay (FA) for the precious metal. The concentrate was digested with aqua regia (AR) for 24 h. Modified AR, where hydrochloric acid was replaced with hydrobromic acid, was used for the gold digestion due to the good match in molecular recognition between gold bromide ion (AuBr)− and α- CD in a second sphere coordination complex. The digestate was characterized using atomic absorption spectroscopy (AAS). Gold recovery using this technique is pH sensitive, and five pH values (2.0, 3.6, 4.0, 5.4, and 6.0) were investigated. FA analysis showed the Shanono gold ore deposit contains an average of 4.71 ppm of gold, AAS analysis showed highest gold recovery of 69% at pH 4.0, which is lower than recoveries from the metal scraps. This could be due to the presence of other gangue minerals closely associated with the ore. However, gold recovery using α-CD on Shanono gold ore has shown to have a higher yield of 69% compared to 35.5% yield obtainable by Artisan Small Scale Miners using mercury.

May 5, 2020

By Neil Rowlands

Particle liberation studies are commonly used in the determination of the proportion of locked and liberated phases in ground ores at various stages of mineral processing. These studies may range from a qualitative assessment of a polished specimen in an optical microscope to a full quantitative analysis of the liberation characteristics of fine grained complex sulfide ores using scanning electron microscopy and high level image analysis. However, the conversion of quantitative data to meaningful information on a mill operations level is by no means a simple task. This paper reviews the errors inherent in the SEM/Image Analysis technique and looks at the various methods available to minimize errors in data collection.

Jan 1, 1992

By C. A. Rowland

The rising costs for and the possibility for limited availability of electrical energy are emphasizing the continual conflict faced in the selection of comminution circuits used in preparing ores for concentration, namely; capital cost vs. operating cost. Frequently, the circuit with the lowest capital cost is not the most efficient in the use of electrical power and wear resistant materials. The simplest circuit in terms of flow, pieces of equipment and capital cost is the single stage autogenous or partial autogenous circuit used to grinding primary crusher discharge or run of mine ore to the desired product size. (Fig. 1) From this circuit, complexity increases to multi-stage crushing circuits preparing feed for multi-stage grinding circuits. Fig. 2 showing a three stage rod mill ball mill arrangement is an example of a complex grinding circuit. Stage concentration further complicates the flow. Multi-stage circuits being the most expensive to install, often give the greatest operating flexibility and offer the best possibilities for the most efficient use of available power and wear resistant materials. Within available grinding circuits, other comparisons such as high speed vs. low speed mills, grate discharge vs. overflow discharge, metal liners vs. rubber liners, high charge vs. low charge, etc. all add to the conflict

Jan 1, 1977

By D. Purdie

"This paper aims to remind researchers, designers, operators, and managers about the benefits of seeding in the design of precipitation stages in their flowsheet. Including a high density solids (HDS™) process encourages the precipitating solids to form on the surface of existing precipitated particles. This paper discusses the application of the HDS technology at Kennecott Smelter, where the authors have witnessed significant improvements in settling and filtration rates. The authors have also applied this technology at various smelter bleed treatment plants worldwide with similar improvements in precipitation and filtration rates. HDS is a registered trademark of De Nora Water Technologies. RÉSUMÉ Cet article a pour objectif de rappeler aux chercheurs, aux concepteurs, aux exploitants et aux administrateurs les avantages de l’ensemencement dans la conception des étapes de précipitation de leur schéma de traitement. L’introduction d’un procédé des boues haute densité (procédé HDS™, de l’anglais high density sludge) encourage la formation de substances solides précipitantes à la surface des particules précipitées existantes. Cet article porte sur l’application de la technologie HDS à la fonderie Kennecott, où les auteurs ont observé des améliorations importantes au niveau de la vitesse de sédimentation et de filtration. Ils ont également appliqué cette technologie à diverses usines de traitement des rejets liquides des fonderies dans le monde entier, et ont constaté des améliorations similaires en termes de vitesse de précipitation et de filtration. Le procédé HDS est une marque de commerce déposée du fabricant De Nora Water Technologies.INTRODUCTION In 1966, the lead author worked as an assistant smelting metallurgist for the Tsumeb Corporation Limited copper and lead smelter in Tsumeb, Namibia. The smelter produced copper and lead, as well as cadmium and arsenic trioxide as byproducts. The cadmium was concentrated in the lead blast furnace off gas dust, and was collected by a baghouse. The baghouse dust was leached with dilute sulfuric acid (H2SO4) in a batch process. The iron and arsenic in the solution were oxidized with potassium permanganate (KMnO4) and basic ferric arsenate (BFAS; Fe(AsO4)x(SO4)y(OH)z·wH2O) was precipitated using milk of lime. The cadmium was cemented from the purified solution using zinc dust."

Jan 1, 2018

Growing concerns of climate change and its potential association with the release of greenhouse gasses to the atmosphere have prompted possible legislation which would require minimization of greenhouse gas emissions. Carbon dioxide and methane, both of which largely contribute to the greenhouse effect, have direct links to the fossil energy industry sector. Specifically, the combustion of one ton of coal produces between one and three tons of carbon dioxide, dependent upon the carbon content and heating value of the combusted coal. Additionally, coal mine methane (CMM) released through a mine?s ventilation system has a radiative trapping impact approximately 20 times greater than that of an equivalent mass of carbon dioxide. The capture of coalbed methane (CBM) prior to the mining process and its utilization as an alternative energy source provides the possibility of a decreased carbon footprint. Domestically, the past 25 years have seen a significant expansion of the CBM industry. Internationally, in developing countries such as China, the need for western coal degasification technology is growing. A collaborative, international effort will be required to initiate a recognizable decrease in global greenhouse gas emissions. This paper identifies the potential decrease in equivalent carbon dioxide emissions through effective degasification at a hypothetical longwall mine located in China. Advanced, three-dimensional gas reservoir simulation software will be utilized to determine the maximum feasible CBM recovery in a low permeability, high gas content reservoir prior to the mining process.

Jan 1, 2010