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By S. K. Kawatra, T. C. Eisele

Microorganisms, such as the bacteria Thiobacillus ferrooxidans, have been reported to depress pyrite flotation (Elzeky and Attia, 1987; Atkins, 1990). However, the depen¬dence of the depression on the type of organism or on suspension pH is still being determined. In this study, the relative effectiveness of various microorganisms (chemolithotrophic bacteria, chemoorganotrophic bacteria and yeast) over the pH range of 2 to 12 was studied. Screen¬ing tests using microflotation showed that every microorgan¬ism tested was capable of depressing naturally hydrophobic pyrite at acidic pH. Larger-scale experiments with both mineral pyrite and coal pyrite using Thiobacillus ferrooxidans and Saccharomyces cerevisiae as depressants, showed that these microorganisms are very effective depressants for mineral pyrite at acid pH, but they are largely ineffective at neutral and alkaline pH, where the mineral pyrite surface is not naturally hydrophobic. The flotation response of the coal pyrite was completely different from the mineral pyrite. The coal pyrite was most floatable near neutral pH, with the floatability decreasing in acidic or alkaline solutions. De¬pression of the coal pyrite by yeast was not selective between the pyrite and the associated coal under the experimental conditions.

Jan 1, 2000

By Michael Brittan

The AARL elution process has recently been introduced to the North American mining industry by Bateman Engineers Inc. The process is described along with its noteworthy features. Design and operating considerations are discussed.

Jan 1, 1998

By Robert Turner

Gold and silver processing techniques are some of the oldest in the mining industry. Gold mining of high grade veins and deposits has existed for centuries. However, only with the higher gold prices in recent years and heap leaching techniques have the low grade gold and silver deposits become feasible to mine and process economically. By mining and hauling 3,600,000 tons of ore per year at an average grade of 0.03 ounces/ton gold and 0.385 ounces/ton silver, the Zortman- Landusky operations became profitable in 1982. To maintain profitably, a stripping ratio of less than one ton of waste to one ton of ore, and mine run ore placed on the leach pads which will yield approximately seventy percent go1 d recovery.

Jan 1, 1984

Remote sensing methods have been used to evaluate vegetative growth patterns for many applications, though relatively little work has focused on tracking mine reclamation progress. For coal mines in Central Appalachia, reclamation approaches that include production of biofuel feedstocks are increasingly attractive, as these may yield significant post-mining land values and contribute to carbon-neutral energy supplies. To optimize biomass productivity, the influence of reclamation practices on biomass production must be well understood, which necessitates tracking biomass production over long time periods. Satellite-based estimations may offer low-cost alternatives to conventional biomass estimations and, also, the potential to provide critical input for carbon accounting at varied spatial scales. In this paper, experimental biomass production plots on reclaimed mine sites established in Wise County, VA, are used for a comparative study of satellite spectral derivatives, which are evaluated against groundbased biomass estimates. Metrics based on four spectral derivatives, band ratios and spectral transforms were regressed against biomass measured in situ for different species. The results demonstrate that greenness and principal component 2 (PC2) were more efficient than the other spectral derivatives for monitoring the biomass of this reclaimed area. Also, it is shown that Landsat-5 TM has provided promising results for monitoring of the biomass changes occurring from 2008 to 2010 over the study area.

By V. M. Torres

An empirical correlation to detennine laboratory mill grinding time has been developed. Grinding samples to 90 ± 5# below 147 micrometers was required for a flotation testwork at Companhia Vale do Rio Doce (CVRD) Research Center. The initial samples were all below 1 mm in size with different size distributions and work indices (Wi) ranging from 13 to 23 kWh/st. Grinding curves were determined for some initial samples. A correlation was developed between percent retained on 147 micrometers at a standard time and the time required to grind each sample to the required size. This correlation was then used to grind all samples, based on the preliminary grinding model. Finally, a statistical analysis with the size distribution of all samples was performed. The success of using the correlation was confirmed and an equation was determined using the data set.

Jan 1, 1996

By Paul R. Thomas

This paper addresses the long-term cost and availability of primary gold production from the Republic of South Africa. Forty-four major producing or developing operations were evaluated. The analyses present estimates concerning 1) total refined gold potentially available from demonstrated resources, 2) annual production potential into the next century, 3) long-term weighted average total costs for underground mine production and surface waste reprocessing, 4) the expected annual decrease in gold production, and 5) the ability of other market economy countries to compensate for the anticipated decline in South African gold output. This paper draws upon the data and analyses of a recent Bureau of Mines, U.S. Department of the Interior, Minerals Availability Program appraisal that evaluated the worldwide availability of gold and silver from primary precious metal operations and as a byproduct of base metal production.

Jan 1, 1984

By L. B. Paterson

Mining Engineers throughout the world have an appreciation for the importance of the role of the Blasthole Drill in one of the primary elements of the mining process. This paper highlights areas that could influence the overall cost effectiveness of that process of breaking rock and how equipment is designed and configured to meet that challenge. Factors influencing drill productivity and overall cost effectiveness are addressed, both in the Mine Environment and on the Blasthole Drill.

Jan 1, 1999

By Cao Changlin, Gong Qian, Hu Jiexue

The thiosulfate, effects copper of concentrations of and ammonia ou the extractlon of gold from sulfide gold concentrate have been studied. The experimental results showed that it is possible to reduce thiosulfate concentration. Above 95% of gold extraction was obtained in O. 2M thiosulfate leaching solution in two hours under the suitable conditions. Therefore, the process of washing residue was simplified, the consumption of thiosulfate and the loss of thiosulfate carried were reduced. by washing residued.

Jan 1, 1992

By Paul M. Godlewski, Roberto J. Guardia

Hundreds of highway and rail transportation tunnels in North America have been rehabilitated in the last two decades. Tunnel rehabilitation is usually dictated by an owner’s need to extend the working life of the structure, but typically has the added benefit of increasing capacity (greater speed or increased clearance) and enhancing safety. Not only has rehabilitation proven to be an economical alternative to new tunneling, but it can be safely accomplished by working during short work “windows” without taking the tunnel out of service. This paper presents methodology for planning and designing of tunnel rehabilitation projects, and case histories illustrate successful excavation and support technologies.

Jan 1, 2003

By X. Nie

A new one-step process was developed to completely eliminate iron and directly obtain pure Ni, Co, and Cu chloride catholyte from nickel rich matte by low temperature (400 0c) chlorination roasting of Ni, Co, and Cu with HCl and leaching with water (PH 7). The effects of roasting temperature, time, oxygen potential and HCI addition and leaching temperature, pH, H2S04 addition and residue sulphur on the recovery of metals and purity of leaching solution were investigated. More than 99 % of Ni and Co and 95 % of Cu in the matte was directly extracted into the solution while 99.995 % of Fe remained in the residue. The iron concentration in the leaching solution was less than 3.6 X 10-5 mol/L.

Jan 1, 1994

By Pradip

The development of highly selective mineral processing reagents, which are not merely metal-ion specific, but specific to the particular mineral surface structure, is essential for the exploitation of relatively more difficult-to-process ore deposits, in particular for the separation amongst minerals having the same constituent ion. Both the choice of the functional group as well as the molecular architecture of the reagent determine its selectivity. Several examples are presented in this paper to illustrate the concepts of structure specificity and molecular recognition at mineral surfaces - the concepts crucial to the advancement of the emerging science of reagents design. Recent advances made in the understanding of molecular interactions involved in the synthesis of biomineralized materials are discussed so as to delineate the utility of this approach in the design of selective reagents for mineral separation.

Jan 1, 1994

By F. F. Aplan

Rather than reiterate what is well known about the flotation of the non-sulfide minerals, emphasis has been placed on those separations which are not so effective. These difficult separations are largely connected with problems of selectivity in the flotation of the base metal oxides, the other slightly soluble minerals, the insoluble oxides and the naturally floatable minerals. The paper discusses possible methods of improving selectivity between similar species and of improving selectivity against the gangue minerals.

Jan 1, 1994

By Hooman Askari-Nasab, AHLAM MAREMI, EUGENE BEN-AWUAH

In oil sands mining, tailings are voluminous unwanted byproducts generated from extracting the desired mineral from the mined ore. Dyke construction and backfilling activities require well-managed techniques to facilitate progressive reclamation at the earliest opportunity. This directly affects the sustainability and profitability of the mining operation. This research introduces a goal programming framework that simultaneously optimizes the (1) production schedule with limited duration stockpiling and directional mining, (2) dyke construction schedule, (3) size, shape and location of tailing cells and (4) mining and processing production targets. The results show that in creating in-pit tailing-cell designs, decreasing the mining-cell volume and increasing the number of mining cells improves the net present value (NPV) of the operation due to increased operational flexibility.

By Mahmut Altiner

This study aimed to produce magnesium oxide (MgO) particles with different properties from dolomite ore using an experimental procedure comprising four stages: sample preparation (S1), HCl leaching (S2), precipitation (S3), and calcination (S4). Three different base sources (NaOH, KOH, and NH4OH) were used as precipitant in the third stage to obtain magnesium hydroxide [Mg(OH)2] from a leachate solution, which was obtained in the second stage. Next, Mg(OH)2 particles generated by different alkali sources were calcined at various temperatures from 600–1000 °C for different durations (1–5 h). The effect of these base types on the properties of each product was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), atomic force microscopy (AFM), and wet chemical analyses. The experimental results indicated that each product was identified as periclase (MgO) mineral, which was produced with a specific surface area (SSA) of 4.49–44.54 m2 /g depending on the production conditions. The surface roughness of the MgO particles increased with increasing calcination temperature. SEM analyses showed that MgO particles produced at a temperature of 600 or 800 °C were amorphous, indicating that the process was not influenced by the base type, but MgO crystals were smooth when the calcination temperature was 1000 °C. Finally, it was determined from all experimental findings that MgO particles produced via the addition of NaOH have superior properties (such as higher SSA and lower surface roughness) compared with MgO particles produced with KOH or NH4OH as the alkali source. These properties led to great improvement of its usability in industry.

By C. R. Euston, B. T. Field, W. E. Lindquist

Pyroprocessing applications in the minerals industry range from low-temperature drying to high-temperature reactions. Material characteristics and process requirements range over a very broad spectrum and can confuse plant engineers trying to select a pyroprocessirtg system for their plant. This paper examines the important process variables and offers empirical guidelines to assist in a user's overall process evaluation.

Jan 1, 2000

By Cengiz Karagüzel, Ömer Canıeren

The mobility of gold and silver metals from refractory ores is very low due to free metal ions in their bodies that bind the transportable and free metal molecules or they are encapsulated in minerals such as sulfides, arsenosulfides, carbonaceous, and clayey materials which make it difficult to extract them. As known from the literature, the enrichment of oxide refractory gold, silver ores, Ag, and Au-rich flotation concentrated from sulfur refractory ores can be leached in the chloride-hypochlorite solutions. In this work, the leaching approach was studied to extract silver ions from refractory ores in the presence of hypochlorite media under high pressure. The mineralogical and scanning electron microscopy analysis of the sample indicated that the silver was encapsulated in barite and quartz minerals in fine sizes. In order to obtain the optimum leaching conditions for the silver ore, the effects of several parameters, namely, temperature, leaching time, NaCl and NaOCl concentration, solid ratio, and particle size on the leaching recovery were investigated in detail. The leaching experiments showed that the highest silver recovery of 62.35% was obtained under the following conditions: temperature of 150 °C, oxygen pressure of 1800 kPa, leaching time of 2 h, concentrations of 2 mol/dm3 and 0.4 mol/dm3 for NaCl and NaOCl, respectively, the solid ratio of 30%, and particle size (d80) 15 μm. The results obtained from this study indicated that the enrichment of refractory silver ores to extract the silver encapsulated in barite and quartz minerals could be possible in the chlorite-hypochlorite under high pressure, a relatively shorter leaching time compared to conventional cyanide leaching.

Jan 28, 2021

By Karl O. Toppel, Jim Flaherty

The desire to minimize gaseous effluent in smelting and maximize gold yields from refractory ore are driving the nonferrous and gold refining industries to demand more and more oxygen. This, coupled with an increasingly competitive marketplace, forces the investigation of alternate methods of oxygen supply. Current progress in both the non-cryogenic and cryogenic fields is making the use of low-purity oxygen much more attractive. The benefits of on-site production are now available to most oxygen users. Historically, these on-site advantages could only be achieved by relatively large plants using high-purity cryogenic technology. The evolution of low-purity cryogenic and non­cryogenic oxygen production has added a new method of delivering on-site production. Specifically, the advent of oxygen Vacuum Swing Adsorption (VSA) technology has brought these benefits to smaller-volume customers by cost-effectively supplying oxygen requirements as low as 20 tons per day, (tpd). Low-purity cryogenic plants have also made an impact on the market, yielding cost reductions for larger-volume customers with oygen requirements greater than 70 tpd. This paper reviews the advantages and disadvantages of current supply methods for users having varying volume, purity and other requirements.

Jan 1, 1993

By P. Somasundaran, S. E. El-Mofty

A comparison of the IMC Anionic Process and the CLDRI Process, based on pilot plant testing of waste pebble by Jacobs Engineering is presented. Estimated costs for constructing and operating a beneficiation plant utilizing dolomite flotation are given. Research to develop practical flotation processes for removing dolomite from low-grade phosphate rock has been a high priority for the Florida Institute of Phosphate Research. The Institute funded the above pilot plant programs in 1998 and 2000. The Florida Phosphate industry currently deals with the increasing dolomite content of ore reserves by practicing selective mining. Heavy media separation plants installed at two mines to remove dolomite from pebble are not being operated. The flotation separation of dolomite from waste pebble requires that the flotation feed be ground. Grinding liberates the mineral species and produces particle sizes small enough to be floated. Only two dolomite flotation processes, the IMC Anionic Process and the CLDRI Process, have been successfully demonstrated on flotation feed that has not been deslimed after grinding. Deslimed flotation feed, relative to undeslimed feed, has improved flotation performance and reduced reagent consumption. However, for the above mention processes, undeslimed ground feed increases the yield of concentrate because the phosphate desliming losses are avoided.

Jan 1, 2002

By L. Hales

Neural networks are a generalized, multivariable non-linear modeling technique that can be used to model mineral processing operations. Neural networks will be described as will their use in modeling column flotation. Optimization of column flotation will be explored and discussed by using the neural network column models.

Jan 1, 1996

By H. M. Breza

Recovery of phosphate concentrate has received increased attention as the existing mine and plant production capacity limitations of the Texasgulf Inc. Aurora, North Carolina Mine are reached. Improved mining techniques and mineral processing of waste streams offer a potential to increase overall phosphate production without major expansion of the Mining facility. Innovative processes have been or are being identified to maximize pit mining recovery and to minimize losses in waste streams, resulting in more effective use of the valuable phosphate natural resource. This paper will describe the various continuous recovery improvement programs being implemented to achieve this goal.

Jan 1, 1994