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By B. A. Hancock

It is not at all surprising that causticized potato and potato derived amylopectin starch solutions performed much better than their parent starches. Some preparation is required to rupture the starch granules to effect the polymeric adsorption and interparticle bridging necessary for selective flocculation. In laboratory work comparing the deslime performance of causticized and autoclave cooked laboratory corn starch solution preparations, it was found that higher deslime weight rejections, with attendant proportionally greater iron unit losses, occurred with the causticized starch. These results may be specific to the ore involved but they do suggest that cooking and causticizing cause different starch granule rup- ture and/or starch breakdown, which have an effect on desliming response. I calculated from the data in the article that the slimes product grades were high - 24.3% and 20.3% Fe when 53.7% and 54.5% Fe concentrate products were obtained, respectively, in Table 4, and 21% Fe with a 62.6% Fe concentrate in Table 5 - using the natural tailings sample, which had a head of 34.3% Fe. It may be advisable for the authors to consider different starch preparations in future investigations. The combination of upgrading and selectivity results presented in Table 4 are not as good as the authors suggest. The authors' claim that a system has been developed to produce saleable concentrates from the Kudremukh tailings is quite disconcerting. There are many hurdles yet to be crossed before commercial application of selective flocculation becomes possible because differ- ences between the very small-scale laboratory tests conducted and commercial application are rather large. Among the many differences are varying circuit feed grades that will occur from use of tailings, the apparent face that much lower tailings grades will be encountered in practice (it is much easier to achieve a high concentrate grade with reasonable recoveries using 34.3% Fe tailings as in the study rather than 25.3% Fe tailings grades that the plant apparently averages), the hydraulic nature of the thickeners used in operations compared to the static system used in laboratory tests, the different size distributions that will be obtained from a plant closed grinding- classification circuit, and differences in water used in a plant operation and the laboratory. The authors wrote that it was necessary to overgrind to be sure that the coarse gangue would not settle with the iron oxide floccules. This situation is likely to be exaggerated in commercial operations where it is assumed cyclones would be used for classification. Because cyclone classification is greatly influenced by particle densities, there will probably be an even greater difference in size between the iron and gangue particles in the plant, which would make the gangue slightly coarser still in relation to the iron. This would make the selective flocculation-desliming separations using the procedure employed by the authors even more difficult and, using the dispersant system the authors employed, greater overgrinding would be required. To grind finer to minimize the coarse gangue in the flocculated iron oxides is quite inefficient and appears not to broach the problem. The actual problem appears to be insufficient dispersion of the ground pulp. In this situation, addition of a dispersant would likely be required to attain a sufficiently high pulp dispersion level to efficiently effect a selective flocculation-desliming separation. Although the very coarse particles would still have a tendency to settle with the floccules, it probably would be found unnecessary to overgrind as much as indicated. Use of an optimum combination of dispersant and pH modifying reagents may also significantly improve the selectivity of desliming. Additionally, although it is possible that sufficient dispersion may be obtained by pH control alone in some situations, it is quite probable that added dispersity was obtained in the reported work from using distilled water. It is research experience that distilled water enhances dispersion. In commercial operations it may not be expected that sufficient dispersion will be obtained by pH control alone, unless the water used in the process is by nature quite dispersive. Overall, a change in the Kudremukh tailings dispersant scheme appears necessary where a dispersant is used in conjunction with a pH modifying reagent. With this change, different dispersion-flocculation responses will result that would have to be further evaluated. Therefore, it is still an open question whether an efficient and effective selective floccula- tion separation using Kudremukh tailings may be obtained that will produce saleable concentrates.

Jan 1, 1987

By A. Dadgar, R. H. Sergent

Changes in the ore types available and increased environmental concern have created a demand for an alternative technology to cyanide for the extraction of gold from ore. Great Lakes Chemical Corporation (Great Lakes) believes that halogen chemistry, in particular bromine chemistry, is the best available alternative to cyanide for gold extraction. Great Lakes is a Fortune 500 chemical company with sales of approximately one billion dollars per year. Great Lakes extracts elemental bromine from naturally occurring brines in Southern Arkansas. Great Lakes has developed a family of proprietary bromine compounds to aid in the extraction of gold. In addition to proprietary bromine compounds for gold extraction, Great Lakes has developed a method of recycling bromide ion in the leach circuit. Various recovery methods, including ion exchange and solvent , extraction are currently being studied.

Jan 1, 1990

By E. K. Albert

Title IV of the 1977 Surface Mining Control and Reclamation Act (SMCRA) provides for an abandoned mine reclamation fund. This fund, taken from fees collected from operating coal mines, provides capital for the reclamation process. The Act directs the Office of Surface Mining (OSM) to collect the fees based on coal production. Monies from the abandoned mine lands (AML) fund are distributed through two programs. The first provides OSM with capital to use in emergency situations resulting from abandoned mine sites and reclaiming high priority sites in states without established AML programs. The second distributes the money through a state's AML program in the form of grants. To provide for a flexible and customized selection procedure for AML projects, a management information system (MIS) that combines scientific selection procedures is being developed. This system employs objective and subjective methods developed in systems research in recent years. The MIS component is an essential part of any selection process involving large numbers of potential projects. It must contain all the necessary project parameters that can be applied to the selection of projects whether or not they are to be used in the immediate selection criteria. In addition, variable selection criteria will allow ‘what if’ types of inquiries for comparison of differing selections and benefits.

Jan 1, 1990

By D. L. Johnson

A number of small but rich copper sulfide (chalcocite) ore deposits are located on Michigan's Keweenaw Peninsula. These deposits are considered too small to warrant the capital investment required for conventional mining. However, they are being considered for in-situ solution mining as a way to revitalize the area's once prosperous copper extraction industry. Geology, mineralogy and geohydrology of the deposits have been investigated to determine their suitability for leaching; Three conclusions were drawn from the work. First, the sulfide mineralization is found primarily in fractures (65%) and, therefore, is accessible to injected leach solutions. Second, the ores are shallow, occurring from surface exposure to about 200 meters depth; injection and recovery wells would not have to be excessively deep. Third, the rock was found to have low permeability, in the neighborhood of thirty millidarcys or less. However, preliminary hydraulic fracturing experiments indicate that this will be an effective method for permeability enhancement. In one experiment a permeability increase of 100 times was achieved using a very low injection pressure at shallow depth. Additionally, fracture aperture spacings measured from drill core were correlated with fair success to field permeabilities.

Jan 1, 1989

By Theodore Budd, Joseph A. Sopko

Ground freezing was selected to provide excavation support and ground water control for the construction of a 457 cm diameter tunnel between two underground structures for a major sewer project in Milwaukee, Wisconsin. Initial plans called for installing horizontal refrigeration pipes around the perimeter of the tunnel. Due to the possibility of difficult conditions associated with horizontal drilling, the contractor elected to drill inclined pipes from the surface. The surface location, however, crossed a city thoroughfare with an extensive system of buried utilities. This paper discusses drilling techniques and utility protection, as well as tunneling methods and production.

Jan 1, 1991

By Curt Morgan

This paper will discuss the value of cream a common information model for the mining industry. Information models are a proven technique for quantifying diverse information in a non-proprietary and easily understood manner. Combining information models with emergent data exchange technologies such as XML and SOAP, the mining industry could substantially reduce the costs of sharing information, reduce dependence on proprietary information systems, leverage inexpensive PC desktop technology, and provide a solid foundation for simplifying mine information systems. The paper will provide an overview of information modeling, discuss practical and proven applications of the modeling technique in the mining industry, propose how such a model could be developed in a collaborative manner and discuss the benefits of such an effort.

Jan 1, 2002

By Andy Cole, Stanley Bunk, Steve Dunn, Thom McCord

In 1994, Goldstrike initiated a research program to investigate processing options for treating what was then the small amount of carbonaceous ore identified in the reserves. The focus of the research was on developing a process which incorporated the autoclave technology already utilized at Goldstrike. Over the next two years, Barrick pursued the development of an ammonium thiosulfate leaching (ATS) process. During the period in which the ATS research was being conducted the amount of carbonaceous ore in Goldstrike's reserves increased substantially and continued growth was projected. By 1996, significant advancement was made on the development of the ATS process. The work culminated in a series of integrated pilot plant runs incorporating autoclaving, ATS leaching, resin in leach, stripping and cementation. Several questions about the process chemistry remained unanswered, preventing commercial development. Barrick was committed to producing gold from the carbonaceous ore reserves by 2000. A due diligence review of carbonaceous ore processing options was initiated during the second half of 1996. Processes considered in addition to ATS were fine grinding/autoclaving, as practiced then by Santa Fe, and whole ore roasting as practiced by Independence Mining and Newmont. The objective by year-end was to recommend the most robust and economical process for Goldstrike's carbonaceous resources. In the fall of 1996, a detailed review of roasting as a processing alternative for Goldstrike was initiated. Throughout the ATS development period, whole ore roasting was used as the benchmark. All the ATS metallurgical and financial results were compared to roasting bench top test results. It was clear this data was too imprecise for use in due diligence study, a more definitive recovery value was needed to complete the carbonaceous ore review. The primary goal of the roasting review was to conduct pilot plant roast tests to gain a more thorough understanding of Goldstrike's carbonaceous ore's response to roasting and its effects on gold recovery. Using the test facility at Hazen Research, four pilot plant campaigns were conducted to determine optimum roast conditions and further define metallurgical design parameters. Conventional two-stage fluid bed technology based on Freeport­McMoRan's roasting patent was the specific process basis for testing. The ore's response to roasting exceeded expectations. In January 1997, a preliminary economic evaluation comparing ATS and roasting was presented, and the outcome was approval to proceed with a roasting prefeasibility study. In July 1997, approval for Goldstrike's Roaster facility was received and basic engineering started immediately thereafter. Detailed engineering _began in January 1998 and plant construction commenced in October 1998,t, Goldstrike's Roaster facility is designed to treat 12,000 tpd of a refractory gold ore, which contains both pyrite and organic carbon. Circuits in the facility include primary and secondary crushing, dry grinding, roasting, gas handling, neutralization, thickening and standard CIL. Gold desorbtion and recovery is carried out at Goldstrike's existing refinery. Plant start-up of the first dry grinding and roasting train is scheduled for March 2000, with the second train coming online in May 2000.

Jan 1, 1999

By Timothy N. Dunne, Joseph M. Gonzalez

This paper presents the case history of a comprehensive geotechnical investigation for the Crosstown Transport Facility, a 10,880 m long, 3.2 m diameter pressure tunnel proposed for construction in San Francisco, California. The proposed tunnel would be part of the City and County of San Francisco's Clean Water Program, and its purpose would be to convey stormwater and sewage from the east side of the City to the Pacific Ocean. Tunneling conditions were defined by surface geologic mapping, 94 exploratory borings, surface and borehole geophysics, aquifer testing, Goodman Jack testing, pressuremeter testing, and laboratory testing. Through the use of advanced coring techniques and a strictly controlled drilling fluid system, core recovery averaged 90 percent in the sheared and fractured rock of the Franciscan Formation. As a result, over 1,400 linear meters of rock core was recovered and is available for examination.

Jan 1, 1983

By D. Boufounos

The large open pit areas of surface mining as well as the huge quantities of residues generated during the digestion of bauxite with sodium hydroxide solution to produce alumina are considered as the most important environmental problems associated with the exploitation of bauxites. Aluminum of Greece, which is the only aluminum refinery in the country, located in Agios Nicolaos, Paralia Distomou, Viotia, produces almost 680.000 tones of bauxite residue annually which is pumped through pipes from the refinery to the sea bed of Antikira gulf. In order to avoid any kind of environmental problems related to this disposal method and to reduce the total volume of bauxite residue disposed of in the environment, Aluminium of Greece investigates several alternatives for bauxite residue utilization. In this framework, it also examines the potential use of bauxite residues as a filler in abandoned mining open pits. Bauxite residues are mainly composed of fine particles of silica, aluminum, iron, calcium and titanium oxides and hydroxides. Furthermore, the material presents low hydraulic conductivity, slightly higher than the limit posed for low permeability layers by the EC landfill directive. Based on these properties the dry disposal method was selected for disposing bauxite residues in mining open pits since it has many advantages such as reduced overall disposal cost, effective use of land and minimum environmental impacts. The results obtained for this method, which is investigated at demonstration scale, are presented in this paper.

Jan 1, 2005

By Robert S. Post

A highly respected coal mining company in West Virginia updated their stacker belt by switching to a new magnetic coupling. The savings they achieved are the subject of this paper. A steep incline and heavy belt loads are powered by a dual drive arrangement. The magnetic couplings were custom designed for complete fluid coupling retrofit and easy installation in the field. Maintenance personnel updated the drives in just a few hours. Over the following several weeks, adjustments were made to the couplings for optimum performance. Cost savings are found in reduced down time, no coupling maintenance, and equipment protection.

Jan 1, 2000

By Ron Parks

High Pressure Grinding Rolls (HPGR) was introduced to the mineral processing industries in the mid-SO's as a tool for comminuting raw and processed materials. This tool made its an impact in the Cement Industry where it was used as a pre-grinder on existing ball mills, raw and finish grinding in a mill circuit and other various applications. This concept was a big success where the cost of power was high along with the desire to increase capacity. The HPGR reduced the power requirement and increased the capacity in the ball mill due to the finished product produced by the HPGR and the micro fractures in the coarse rock, which reduces the power required to finish grind the rock. This unit has found acceptance in many other industries including diamonds, iron and other selective applications. The diamond industry uses this tool for selective grinding purposes since the kimberlite rock is considerably softer than the actual diamonds. Therefore within a bed of material, kimberlite is crushed to fines and the diamonds are liberated and unharmed. The iron industry primarily uses this tool for concentrate comminution; however, there are installations using this tool as a pebble crusher and in an AG-pebble mill circuit.

Jan 1, 2000

By A. W. Laughlin, C. R. Mansfield, M. J. Ferris, D. A. Cremers

Analytical costs are a major part of exploration programs in developing nations which may lack adequate laboratories. Laser-Induced Breakdown Spectroscopy (LIBS), a variant of atomic emission spectroscopy, can reduce exploration analytical costs and can provide the analytical results in <1minute. CPI is now marketing battery-powered, backpack mounted analyzers, using LIBS to analyze for many elements of interest to the explorationist. LIBS is well suited to the analysis of elements in industrial minerals. Limits of detection in ppm for some of these are: Li-1, Be-2, Na-100,B-33, Sr-10, Ba-300, Cs-1, K-500, Fe-500, Mg-500, andTi-500.

Jan 1, 1999

By Arthur P. Chaves, John A. Meech, Vanessa M. Torres

Process choice for a refractory gold ore can become a controversial issue, especially at the early stages of a project. This happens since at preliminary stages, a simple economic comparison among the main process options is not possible as the differences are usually smaller than the precision of estimates. This paper presents a methodology to assess the suitability of each available technologies using a heuristic approach, were technical, economic, operational and environmental aspects are taken into account using a neural network methodology. This methodology is embedded in an expert system for gold ore process design, Intelligold, which is in the final stages of development.

Jan 1, 2000

The process design of a metallurgical plant follows logical steps, one built on another, to define the circuit requirements. The methodology used and documentation produced is the same for a pre-feasibility study, feasibility study or a complete design, regardless of the process complexity or the commodity. The only difference is the amount of detail developed at each stage. SRK Consulting, an independent, international consulting practice that provides focused advice and solutions to clients, mainly from earth and water resource industries, has consulted on many mining projects around the world. The company was formed in 1974 and now employs more than 1,600 professionals in more than 50 offices on six continents. According to SRK experts, the first element in plant design is collecting metallurgical testwork or operating data from an existing plant. The testwork identifies the process, the metallurgical recoveries and product qualities and establishes the process parameters for economic recovery of the commodity. Test samples must represent both the whole orebody and the feed over the life of the mine, showing the mineral?s variability. With this data available, the process design can be developed.

May 1, 2013

By M. P. Corriveau

This is the case history of how two nearby plants in Southwest Virginia solved their water clarification problems. While the solutions should not be considered applicable industry-wide, the methods used in arriving at the answers deserve consideration. When Clinchfield&apos;s Moss No. 2 Preparation Plant, the first ever built in Tiller Seam coal, was started in the fall of 1956, the clays in the raw coal soon posed a flocculation problem, Laboratory sedimentation tests were initiated; and as a result, lime was adopted as the flocculant for the clays, With lime, a pH of 11.2 was required. As the plant tonnage increased, it became evident that the amount of coal fines produced in the mining and preparation was greater than had been estimated and that the 90-foot thickener was inadequate in providing sufficient settling time to effect a clarified overflow for reuse. Testing showed that Separan 26105 (NP10)1/, when used with lime, was the most satisfactory coal flocculant available,

Jan 1, 1960

By Michael Chender

Introduction Clearly, many problems confront the minerals industry today. Yet, at the same time, there is too much energy spent bemoaning the negative effects of difficult economic circumstances, low metals prices, and adverse government policies. These are factors that cannot be altered by individual mineral company reactions. In fact, as we look to the future, the only thing we can be certain of is that we will continue to be faced with uncertainty. Thus, an area that demands close scrutiny and that can significantly affect a company&apos;s performance in the future is the posture it adopts to deal with uncertainty. This paper looks at how strategies are developing to deal with this issue. It also examines some of the implications that implementing such strategies have for the role of the individual explorationist. Elements of strategy Whether mineral company strategies are based on diversifying or retrenching, on emphasizing primary production or downstream integration, there seems to be increasing agreement that in the current environment strategies must have several features. They need to be information-based - developed out of access to timely and complete data and analysis about proposed directions and competitor activity, rather than simply following a current fashion. They need to be flexible - adaptable in light of changes in the marketplace and an unpredictable industry. And they need to be cost-efficient - making the most of limited resources. Whether a company is looking for gold financing opportunities, acquiring polymetallic prospects, or doing grassroots exploration for diamonds, these three elements are increasingly essential. They not only allow the company to pursue its current goals most expeditiously, but also open it to hearing and using feedback in the most constructive way. The company can then improve or change strategy as it proceeds. And it can be best positioned to take advantage of opportunities as they arise. These elements of strategy place great emphasis on the skills of the individual. The need for critical intelligence and the reduced amount of capital available to manage are making it more obvious that exploration is a "people" business. This is in accordance with a general trend in many sectors of industrialized economies, reflecting the widely discussed shift from smokestack to information-based industries. Increasing the odds There is a direct connection between successfully implementing the approaches to strategy discussed above and encouraging and improving the quality of work of the individual explorationist. To illustrate the importance of this, some commonly quoted figures on the odds of discovery success can be used. These figures are arbitrary but illustrative. Assume that one out of 100 exploration prospects actually turns out to be a promising ore body, and that one out of 1000 becomes a mine. Based on our research, chances are the most of those

Jan 1, 1986

By John Turner, John A. Gibson, David Cass

Contents A. Introduction B. Description of Robbins Company involvement in several of the English Channel Tunnel projects C. Identification of project requirements and comparison of TBM features D. Description of the manufacturers separate roles in the -235 (T-1) TBM E. T-1 performance to January 15, 1989 F. Summary

Jan 1, 1989

By G. M. Bernard

This paper provides an overview of the various methods and techniques for transporting and stacking ore on heap leach pads. Towards this end, brief discussions of the various methods and techniques important to this process are presented.

Jan 1, 1993

The present contribution examines the main components of a sustainable land reclamation program applicable to surface coal mines and the environmental threats that hinder the transition to sustainable land management. It compares the main ?waste streams? that cause adverse impacts to the environment with the so-called ?best available technologies and managing practices? that are proposed by organisations with high expertise in land management. Also, it addresses the environmental and socio-economic indicators that should be monitored in order to assess the results of the land management program and to allow remedial actions and continuous improvement. Based on the Greek lignite mines experience in land reclamation, this paper presents the common weaknesses of the land management programmes and proposes an improved communication scheme that moves things towards sustainability. This scheme is based on a more rational exploitation of the available economic resources and a constructive dialog between the mining companies, the local authorities, the state institutions and other stakeholders.

Jan 1, 2003

By D. M. Cregger, J. L. Rosenblad, R. E. Ranken

The construction of a large span, high-walled underground opening in a low strength shale rock is unprecedented. The feasibility of constructing a pumped storage project with several tunnels and a large underground powerhouse in low strength shale rested largely on the feasibility of building stable openings large enough to accommodate the required equipment. Because of the lack of experience with large openings in shale, the decision was made to excavate a test adit and test chamber and conduct a multi-faceted geotechnical evaluation program designed to yield pertinent in-situ data on the ability of the shale to accommodate a large underground opening. Factors considered in the shape, size, orientation, and location of the test chamber were: (1) similarity to the anticipated powerhouse chamber, (2) nature of the most important data to be obtained, (3) feasibility of construction, and (4) economics.

Jan 1, 1983