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By Andreas Rubo, Stephen Gos

Over the past couple of decades several endeavours have been made to develop lixiviants with the intention of replacing cyanide in gold leaching. In 1980s these endeavours were largely economically driven, due to cyanide shortages at that time. In more recent times, the driving force has shifted to occupational health and environmental considerations. It is often argued that the high acute toxicity of cyanide alone makes it worthwhile considering to replace it completely by less toxic alternative lixiviants. This has led to having to consider more criteria in the choice of any alternative lixiviants, which have often not been taken into account in the past. The intention of this paper is to review these alternative lixiviants and also review the criteria, which have ultimately led to most of these lixiviants never having found any large scale application, if they passed laboratory stage at all. It is also intended to show, that by handling and treating cyanide in a proper manner, the overall profile for the use of cyanide compared to these alternative lixiviants is very favourable. The question to really be answered is whether there is actually any chemical or process applicable to gold leaching that does not show the high toxicity potential of cyanide and that is still favourable with regard to looking at a broader spectrum of criteria and not only acute toxicity.

Jan 1, 2000

By Cristian Saavedra, Patricio Zarate

Flotation collectors play a crucial role in mineral flotation by selectively adhering to mineral surfaces and aiding in their separation from gangue material. They are heteropolar molecules, as defined by Sutherland and Wark (1955), featuring non-polar hydrocarbon chains and polar groups interacting with mineral surfaces to induce hydrophobicity selectively. The importance of collectors in mineral processing, as underscored by Lotter and Bradshaw (2010), lies in their ability to enhance recovery rates and improve selectivity, thereby optimizing the extraction of valuable minerals from complex ores. Collectors are classified based on their mechanism of action, as proposed by Laskowski (2010). This classification categorizes collectors into three groups: water-soluble compounds, water-insoluble “oily” collectors, and water-insoluble amphipathic compounds forming molecular films at the water/gas interface. This complements the chemical structure-based classification by Sutherland and Wark (1955) and Suoninen and Laajalehto (1993), offering a comprehensive understanding of collector diversity in flotation systems. Collector selection is an iterative process crucial for optimizing mineral processing efficiency, as emphasized by Lotter and Bradshaw (2010). Understanding the significance of collector mixing or synergy outcomes is paramount for enhancing mineral flotation efficiency and sustainability. Taguta, O’Connor, and McFadzean (2018) demonstrate that mixed collector systems enhance interaction enthalpies and microflotation recoveries, indicating improved performance. McFadzean, Castelyn, and O’Connor (2012), along with Critchley and Riaz (1991), delve into investigating synergistic interactions between collectors, offering insights for strategic selection. Observations from the study of collector synergy, as noted by Wakamatsu et al. (1980), reveal nuanced relationships surpassing individual collector behaviors. The methodology outlined in this paper provides valuable guidance for classifying and selecting collectors based on specific application needs, while also suggesting the potential for synergistically improving recovery across fine, intermediate, and coarse particles.

Feb 1, 2025

By R. L. Loofbourow

In addition, dewatering is seldom complete because of aquifer irregularities and an operator's natural reluctance to start a costly study program, provision of wells, and pumping long before mining begins. In some cases, water pumped from the mine is used in treatment. This use is suggested as a way to minimize effluent effects. The true objective of water supply, however, is to provide water of satisfactory quality at the rate needed and at the least cost. Pumping to permit efficient mining isn't likely to coincide strictly with that objective during much of the mine life. The history of mining is replete with efforts, some highly ingenious, to control mine water. Methods that might be used to tackle the challenge Operators of wet mines are faced with both obvious pumping costs and some unquantified water costs. It is possible to reduce both types of costs, generally by reducing inflow to the mine area-and a surprising number of methods have been used to do this. Both the obvious and unquantified costs at a wet mine are now multiplied by: •Increasing costs of power, labor, equipment, and supplies; •Work at greater depth and, in some cases, in wetter ground; •Increasing use of hydraulic fill; and •Increasing zeal in protection of surface and groundwater quality. There are many easily overlooked ways in which mine water may add to hazards and costs (Loofbourow, 1973). As to their importance, consider these examples: •Increased maintenance of equipment, tires, roads, and ditches; •Increased difficulty in supplying proper ventilation; •Increased hazards from ice and use of electric power; • Loss of friable ore minerals and fines stuck on conveyances and in chutes; •Need to use more expensive methods and explosives; and •Decrease productivity of equipment and personnel. Expressed as cost per unit of ore produced, these unquantified costs can be high. Ideally, advanced dewatering should eliminate most of them. Advanced dewatering is a highly effective water control method, but it isn't problem free. Mines in ideal ground for advanced dewatering are most unusual. To be effective, water must be pumped at a comparatively high rate for a period longer than the life of the mine, from below mining depth. Effects on both groundwater and surface water are likely to be drastic. of increasing mine water costs are listed in the accompanying table. Ten groups of possible methods are cited. Most have been demonstrated in mining; two are known from industries other than mining.

Jan 12, 1980

By E. Snyders

Two alternative processes for the manufacturing of zircon products were investigated by the South African Nuclear Energy Corporation (Necsa). These were the synthesis of doped-zircon pigments from plasma dissociated zircon, and an upgrading process to convert an inferior grade of zircon into a superior opacifier for ceramic applications. A solid-state reaction process was used to produce doped-zircon pigments. The influence on the colour intensity of the pigments on a ceramic tile were compared for milled and un-milled plasma dissociated zircon (PDZ) material, prior to calcination. Pr-yellow and V-blue zircon pigments produced from PDZ with different degrees of dissociation, were also evaluated. The second zircon beneficiation process entails the upgrading of an inferior grade of zircon to a superior opacifier for ceramic applications. A calcining process in the presence of mineralizers was used to produce the product in a conventional muffle furnace. A pre-milled inferior grade zircon concentrate, with a relatively high iron and alumina content generally not suitable for high quality ceramic applications, was used in this study. The influence of the upgrading process on the opacifying properties of the zircon material was compared to that of commercially available prime grade zircon opacifier products currently being produced in South Africa. The influence of a calcining step in the presence of mineralizers with regard to the milling characteristics of the treated zircon material was also evaluated.

Jan 1, 2005

By Ellen S. Forbus

Reduction bleaching is used to improve the brightness and color of the kaolin pigments sold to the paper and speciality industries. The bleach re¬duces the iron oxide associated with kaolin deposits to a colorless form by the following reaction: Na2S2O42+ 6Fe+3 + 4 H2O -> 2 NaHSO4 + 6Fe+2 + 6H+ (Conley et al., 1964). At present, sodium hydrosulfite is used by the kaolin industry as the reductive bleach. It is often purchased commercially as a liquid solution and added into an acidified slurry. Before the use of commercial sodium hydrosulfite, kaolin plants manufactured zinc hydrosulfite on site by adding zinc dust to sulfurous acid made by passing SO2 gas into water. This process was abandoned in the 1970s due to environmental concerns about zinc in waste waters. In the 1970s, Engelhard patented a process that made sodium hydrosulfate from an iron hydrosulfate (Tiethof, 1978). Difficulties with separating the iron hydroxide byproduct from the bleach and a decrease in the cost of commercial bleach caused the project to be abandoned.

Jan 1, 1993

By E. S. Forbus

A process for producing reductive bleach in-situ in kaolin slurries has been developed. The bleach is formed by mixing an iron sponge powder (-325M) with slurry treated with SO2. The process has been successfully demonstrated in production, and applied to several grades. The color, brightness, and viscosity of the bleached product is equivalent to or better than that of product bleached with commercial sodium hydrosulfite . The tested products can be bleached at a cost, which is 38-54% of those associated with the use of commercial bleach.

Jan 1, 1993

By E. R. Hoskins

The Gulf Coast States ranging from South Texas to Alabama contain vast resources of lignite ranging in energy content from about 4000 to 7000 Btu/lb (as-received) with sulfur content ranging from about 0.5 to 2 percent. Currently, the strip mining rate is about 35 million tons per year in Texas and essentially zero in the other Gulf Coast states. Estimates of future mining rates are as high as 310 million tons per year by the year 2000 with 240 being in Texas. In this paper, we examine the life cycle of the surface mineable lignice based on the most recent estimates of surface mine recoverable resources with two scenarios. The first indicates that a 310 million tpy rate could be sustained for only 15 years while the second scenario suggests that the 310 million tpy could be sustained for 25 to 30 years. If lignite resources are required beyond those that are surface mineable, the deep basin lignite will be developed. Five strategies for developing deep basin lignite are discussed.

Jan 1, 1983

By Larry Murphy, Mohammad R. Jafari, David M. Giel, Sharat K. Kalluri

"Built in 1940’s to provide a key roadway arterial between New York and Boston, the Heroes Tunnel is the only highway rock tunnel in the state of Connecticut and is part of the Wilbur Cross Parkway. This 365.0 m long tunnel consists of two barrels, each with two lanes of traffic, and carries over 71,000 vehicles per day. For nearly 70 years, the tunnel has seen millions of vehicles pass through but time has taken its toll and now the tunnel lining, ventilation system and radial section joints are significantly deteriorated and in need of rehabilitation. Owned and maintained by the Connecticut Department of Transportation (CTDOT), CTDOT initiated a unique managed approach to mitigate the risk, social impacts and financial implications associated with rehabilitation of this tunnel. This new approach consists of performing field inspection and conducting a comprehensive study to explore six rehabilitation options, including construction of new tunnels and enlarging the existing tunnels. The main criteria for this study are: Impact on traffic and the resulting delay cost; Construction cost; Construction duration; and Construction complexity. This paper will present the results of the alternative study. PROJECT BACKGROUND Location and Importance Heroes Tunnel is located in the State of Connecticut within the Town of Woodbridge and the City of New Haven near the Town of Hamden border. Heroes Tunnel is the only true highway tunnel in the State of Connecticut. The tunnel is part of the Wilbur Cross Parkway (Route 15), a scenic connection between Hartford and New York. Originally constructed and opened to traffic in 1949, the tunneled portion of the parkway passes through the West Rock Ridge. The tunnel was originally named West Rock Tunnel, but was re-designated as Heroes Tunnel in 2003. Route 15 is a vital roadway within the State transportation infrastructure. In the vicinity of Heroes Tunnel, Route 15 carries approximately 71,000 vehicles daily. Locally, Route 15 provides access to residences, shopping centers, and points of interest, as well as other state roadways. Regionally, Route 15 connects New York to the Hartford area and serves as an alternate expressway route to I-95 and I-91. The tunnel is approximately 365.0 m long and passes through the West Rock Ridge. West Rock Ridge is an 11.3 km long rock ridge located on the west side of New Haven. A network of suburban streets abuts the mountain on all sides and a seasonal paved park road climbs to the crest of the ridge. Figure 1 depicts the tunnel topography and location."

Jan 1, 2016

By H. Sevim

In long-term open pit production planning, a series of nested and maximum-value pits is usually generated first. These pits are then considered as possible pushbacks over a number of planning periods. To determine the best pushback in each planning period, the pits are evaluated for their technical and economical feasibilities under certain production constraints. Parameterization is a commonly used technique to generate a series of pits. In almost all cases, however, some of the consecutive pits generated by this technique are too far apart from each other. This is called the "gap" problem. It may make the entire pit series useless for production planning purposes. A new pit gener¬ating algorithm has been developed to overcome the gap problem. Through this algorithm, a series of nested maxi¬mum-value pits can be generated with a controllable size increment. The logic of the algorithm is illustrated through a small hypothetical case. Its capability of generating maximum-value pits that are as optimal as those generated by parameterization and its advantages over parameteriza¬tion are presented through an actual gold deposit case.

Jan 1, 1996

By M. G. Papasotiriou

For our company, S&B Industrial Minerals S.A., restoration of areas which were mined and the effort for bringing up again a balance of nature is an important priority over the last 3 decades. The successful qualitative results of restoration works have delivered to nature over 1.700.000 m2 of surface after mining activity. Our fundamental method in order to achieve the best results for restoration of mined areas is the use of local plants (bush or tree type). Grass and herbs are installed by using the method of hydroseeding. Small trees and bushes are produced and they grow up at our fully owned Milos nursery and they are installed during winter when weather conditions are suitable. During the initial stages of restoration activities a great amount of surfaces, adequately shaped, are delivered by the mining department covered with top soil. These surfaces are suitable not only for the local nature community but also for a combination between natural and agricultural environment. The above fact was a great chance to create small horizontal agricultural cultivations as pilots inside the restored areas. At the beginning the agricultural items that could potentially be installed in these pilot areas were studied and examined analytically. The following agricultural items were finally qualified to be furthermore researched: 1) Vineyard (Vitis vinifera ) 2) Prickly pear (Opuntia ficus indica) 3) Jojoba (Simmonsia chinensis) 4) Olive tree (Olea europea)

Jan 1, 2007

By J. S. Gardner, K. E. Houston, A. Campoli

INTRODUCTION Disposal of coal refuse is a costly and challenging problem facing the coal industry today. After the Martin County Coal Company slurry spill and the subsequent regulatory changes state and federal agencies are now beginning to require companies to justify new slurry impoundments. The authors have performed an analysis of different means of disposing of coal refuse for a major coal producing company located in the eastern Kentucky coalfields (the name of which will be withheld for the purpose of this paper). The company’s existing slurry impoundment is nearing its maximum permitted elevation and also an elevation where it may come in contact with abandoned underground workings. Due to the increased concern with underground mine works near slurry impoundments, additional consideration was given to raising the existing impoundment. Several other alternatives were evaluated, including but not limited to raising the existing impoundment, constructing a new slurry impoundment, constructing slurry cells, belt presses and others. This alternatives analysis was performed as part of a Section 404 permit for a valley fill and is currently being reviewed by the U. S. Army Corp of Engineers. All of the known possible alternatives were discussed in detail in the analysis. Due to the findings of the alternatives analysis, the company considers the engineered construction of the proposed impoundment to be the most favorable option of all the other alternatives evaluated, from both an economic and environmental standpoint. ALTERNATIVES EVALUATION FOR COALREFUSE/SLURRY DISPOSAL Background The company currently operates several deep mines and employ over 300 people and produces over 3.9 clean Mt/a (4 million stpy) of high quality, low sulfur coal. Currently, coarse refuse is belted to a valley fill, while, fine refuse is pumped to the existing impoundment. Coarse refuse is trucked to the existing impoundment as needed for construction purposes. The average recovery is approximately 50%; therefore, over 3.9 Mt/a (4 million stpy) of coal refuse must also be separated and placed.

Jan 1, 2003

By Patricio Zarate

Due to the intrinsic variability in orebodies, similar metallurgical behaviour of all material sent to the concentrator is expected to have some variability. Still some specific ores have anomalous performance which can severely impact on the concentrator’s production of metal, in this case copper. The study first will show the mineralogical characteristics of “usual ore” and of this specific “abnormal ore” which will have to be processed by the concentrator in the future. After that base conditions on both ores and flotation test procedure will be explained. Later the different alternatives tested regarding collectors and modifiers results will be compared. Finally, after discussing the different results with different reagents and considering operational variables of the concentrator, Floticor PD 702 is recommended to obtain the best copper recovery without increase in excess mass recovery.

Feb 1, 2025

By F. C. Nicolli, J. P. Barbosa, P. S. M. Soares, A. V. Estevez

INTRODUCTION Spent household dry cell batteries are frequently disposed of with metropolitan wastestream (MSW) in landfills where they can leak due to handling or aging. Frequent rain and sun cycles, especially in tropical environments, coupled to the action of leachate, dissolve their metal constituents which will eventually reach rivers, lakes and underground water. It is well known that some of these metals are fundamental to sustain life and that is why living organisms concentrate them through their metabolism, but it has been also recognized that beyond specific limits they can definitely be deleterious to the environment. In other words, high concentration of heavy metals are proven to cause chronic or acute diseases and toxic reactions, by acting on mammals' kidneys, liver and nervous system. In addition, some metals frequently used in household batteries, as mercury and cadmium, are said to be carcinogenic (Landis et al. 1995, Silva et al. 1988). Occasionally, plants to treat MSW are coupled to compost production. Household batteries present in MSW can be dragged into these plants, contaminating their products and eventually reaching vegetables making them not proper to consume by people and animals. Alternatively, batteries are also conveyed to incinerators and burned, throwing into the atmosphere volatile species. These can either act as contaminants as toxic vapor species or be delivered by winds and scavenged by rains contaminating soils and water far away from their source. In conclusion, despite the treatment applied to MSW, one can say that battery residues are potentially environmentally hazardous. The careful assessment of the environmental impact caused by residues of household batteries it is not an easy task and it can be referred as a multivariable problem. First, many different household batteries are produced by industry and the potential environmental hazard associated to their disposal depends primarily on the type of battery and manufacturer's technology. These characteristics will dictate how resistant the battery case is to handling and the

Jan 1, 1998

By John A. Herbst, William T. Pate, A. Edward Oblad

Dynamic optimization is a cost-effective means to increase production or improve product quality in a plant. Several model-based approaches to dynamic optimization of mineral processing operations have been developed and implemented in plants. This paper reviews the phenomenological models that are the basis for dynamic optimization and the alternative methods of mathematical optimization. These methods range from theoretically complex and costly to implement to intuitively comprehensible and readily implemented.

Jan 1, 1990

By P. Whincup, T. Showell, B. Marchant, R. Dunne

An oversupply of copper on world markets in the early 90' s, coupled with a decrease in demand, resulted in a "tight" market for the sale of copper concentrate. In these conditions small producers of low grade copper concentrates found it difficult to sell their products. The situation was exacerbated for those producers also having reasonable quantities of penalty elements (e.g. As, Bi). The Telfer Gold Mine bulk copper gold concentrate, produced from treating underground sulphide ore, fell into this category (i.e. 16% to 20% copper, 30% to 35% sulphur and 3500ppm to 4500ppm arsenic). The concentrate sulphide minerals are predominately chalcocite and pyrite. Although a higher grade copper concentrate was attainable a substantial decrease in gold recovery ensued. Under the prevailing market conditions a decision was made to stockpile concentrates pending either an easing of market conditions or alternatively finding an on site method for treating the concentrate to recover both the contained gold and copper.

Jan 1, 1995

By Leonard Sugin

Recent changes in the field of ore and bulk commodity handling has forced a reevaluation of previously conceived notions. When vessels were small, and sources of raw material were reasonably close to areas of need, the role of the shipping terminal was of secondary importance. Now terminals must be built to take advantage of the economic benefits of the supercarriers. The shipping rates of the 80's will not be determined by the 60,000 DWT or even 150,000 ton capacity bulk carrier, but rather by the supercarriers in the 250,000 DWT class or larger. When the Suez Canal was closed, the shipping industry took a hard look at the economics of the large bulk carrier. Naval architects overcame the problems and successfully designed large supertankers, which today are plying the seas in excess of 350,000 DWT. Orders have been placed for tankers of 480,000 DWT. The shippers of dry bulk materials are now coming to similar conclusions about the economics of supercarriers. As of today, over 40 orders have been placed for vessels in the 250,000 DWT class, representing an investment of over 11/2 billion dollars, and many more are being considered. These vessels are being designed as combination ore/oil (0/0) or ore/bulk/oil (OBO's) carriers. The oil industry has seen the need for terminals which can accommodate these supertankers. The dry bulk shippers, and particularly ore shippers, must now act.

Jan 1, 1972

By Francis J. Kiessling

Energy and the conversion of potential energy into alternate forms is becoming a topic of household conversation for a larger segment of the world's population as mankind's desire for products derived from the vast array of technological developments continues to expand. The world's use of steel and the high energy consumption related to the production of steel promotes an awareness of the limitations of existing technology and a search for more economical alternates. Terminology such as (BF) Blast Furnace, (BOP) Basic Oxygen Furnace, (EAF) Electric ARC Furnace, (DR) Direct Reduction, (DRI) Direct Reduced Iron and (FC) form coke is becoming commonplace as alternates are being sought to alleviate the energy crunch. Coke production by various methods was developed as early as the seventeenth century in Europe to replace the disappearing hardwood forests that supplied the initial blast furnace fuel in the form of charcoal. In 1880, the Semet Solvay by-product coke oven design was introduced to the United States at Syracuse, New York, to supply coke for use in the production of soda ash, coke oven gas and its by products as the primary source of many organic processes. Although the Semet Solvay coke oven has not been marketed for decades, these coke oven batteries are in use today producing metallurgical coke, coke oven gas, and related by-products.

Jan 1, 1980

By M. W. Ryan

The US Bureau of Mines investigated cold-cutting alternatives to oxyacetylene torch cutting of metal. The alternatives examined were a pneumatic circular saw with an abrasive cutting wheel, a handheld abrasive water-jet cutting tool, an ultrathermic-cutting system, hydraulic punches and cutters, and a pneumatic reciprocating hacksaw. Sparks generated with the pneumatic circular saw or ultrathermic-cutting system were not completely eliminated with the use of water sprays. The water sprays also reduced the cutting rate of the pneumatic circular saw by 70%. The safety and performance of a handheld abrasive water jet cutting system requires additional research. The hydraulic cutters and punches are readily available and do not introduce any hazards. However, they are not comparable in price to the oxyacetylene gas torch and many different attachments would be needed to replace the torch. The pneumatic reciprocating hacksaw, which did not produce any sparks, is an acceptable alternative in terms of cutting rates. However, the price of the saw and blades is not comparable to that of the oxyacetylene gas torch. The results of this study will further the advancement of safe, efficient alternatives to oxyacetylene gas torches, which will improve miner safety.

Jan 1, 1996

By R. L. Loofbourow

Most wet mines face unquantified water costs as well as the obvious wing costs. Both kinds of cost are multiplied by work at greater depth and by higher unit prices. This intensified challenge merits renewed or perhaps altogether new response. Any practicable way to reduce inflow tackles both obvious and unquantified costs. Ten groups of possible ways to do it are cited. Most have been demonstrated. Two are known from work other than mining. Surely new means can be found. Here are opportunities for operators of wet mines!

Jan 1, 1980

By S. S. Sephton

The La Perla Mine, owned by Altos Hornos de Mexico, S.A., is located approximately 100 miles east of the City of Chihuahua in the State of Chihuahua, Mexico. The mine began operations in 1958. Existing ore beneficiating facilities, consisting of heavy media and jig plants, upgrade the ore prior to shipment by rail to the Altos Hornos steelmaking complex in Monclova. Sizable reserves of two distinct ore types, which were not amenable to treatment in the existing beneficiating plant, or usable in the blast furnaces, have been mined and stockpiled in order to uncover the treatable ores. One of these ore types has been labeled "Diseminado" ore, and is low grade containing approximately 42% Fe with sulphurs ranging from 1 to 2%. The other ore type has been labeled "Pulverulento" ore, and is high grade containing approximately 65% Fe and 0.1% S, but at 80% minus 325 mesh, is too fine grained for efficient sintering. Late in 1968, Arthur G. McKee & Company became involved with the problem of improving the above ores for their efficient and economical use in Altos Hornos' blast furnaces. Early in 1969 representative samples of Diseminado ore were obtained for laboratory bench-scale testing at the University of Minnesota, Mineral Resources Research Center. Concentration tests incorporating magnetic roasting, wet magnetic separation, high intensity separation, high tension magnetic separation, anionic flotation of apatite, cationic flotation of silica and oleic acid flotation of iron were performed. Laboratory testing was concurrently carried on at La Perla Laboratory, which resulted in plans to construct a 10 TPD pilot plant. The pilot plant was operational in September, 1969. Analyzing laboratory results as well as pilot plant results, Altos Hornos and Arthur G. McKee & Company metallurgists agreed that the most promising flowsheet for the low grade Diseminado ores entailed wet magnetic cobbing, desliming, and oleic acid flotation of the non-magnetic fraction. A combined concentrate of

Jan 1, 1972