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By George Owusu, Ernest Peters, A. J. Monhemius, G. W. Warren, David B. Dreisinger, E. Peters

Lignin sulphonic acid (or its salt) is commercially used as a surfactant in the Zinc Pressure Leach process. The surfactant prevents liquid sulphur from coating unreacted zinc minerals thus allowing the leaching reaction to proceed. Infrared studies have been performed using the Attenuated Total Reflection-Fourier trans- form infrared technique (ATR-FTIR); the application of this technique permitted the "in-situ" study of the adsorption of the surfactant by sphalerite. The spectral records obtained from study indicate that the lignin sulphonate ions are both physically and chemically adsorbed by the sphalerite.

Jan 1, 1993

By A. S. Ibrado

The adsorption of silver on activated carbon from cyanide solutions was studied as a function of concentration, ionic strength and pH. In cyanide solutions, silver exists mainly as the linear Ag(CN)2 complex and adsorbs on activated carbon following the Freundlich isotherm. The uptake and rate of adsorption increase with the addition of KC1 and KNO3 but changes only slightly with pH. In contrast, the adsorption of Cu(I), Zn(II), Cd(II), and Hg(II) shows marked changes with pH, closely following the predominance profiles of their neutral and singly-charged cyano complexes. Clearly, multicharged negative complexes are repelled by the negatively-charged carbon surface. This sensitivity of activated carbon to the charge of the adsorbing species indicates that silver adsorbs as an anion, not chemically bound to the co-adsorbing counterions. For the same reason, activated carbon is selective to metals that form neutral and Singly-charged cyano complexes, namely gold and silver.

Jan 1, 1988

By James J. Scott

In 1910 the United States Bureau of Mines was created. It was the outgrowth of a social problem stemming from the fact that 25,000 men were killed in coal mining accidents for the period 1900-1910. Something had to be done and congress responded to the people's demands by creation of this new regulatory agency. At that time mine operators felt the new agency was too strict but nonetheless new rules were developed and enforced and results were obtained by the industry which reduced fatal accidents to less than 250 per year by 1970.*Social reaction by the general public brought about legislation which created the Federal Coal Mine Health and Safety Act of 1969 This legislation was a direct reaction to the Farmington Disaster. Operators and miners alike said "we cannot operate under this law. It is too strict, requirements are unrealistic, production will suffer, .there will not be any improvement in health and safety, etc." Consider the facts: 1. Health and safety have improved. The 1972 frequency and severity rate was the best ever for the bituminous coal mining industry, Figure 1. 2 .Production per manshift has dropped in underground coal mines. For example, in West Virginia from near 16 tons/m.s. in 1967 to nearly 11 tons/m.s. in 1971-72. However, not all of this loss can be attributable to the Act, but certainly some is. (2) The betterment of the safety of coal mining was a prime motivation behind the coal law and from that standpoint the law has been partially successful, but the loss in productivity has been a real burden to the mine operator. Everyone should recognize that the law says little in regard to production--it only relates to health and safety. Production is management's responsibility.

Jan 1, 1973

By Brian Mangogna, Clay McNail, Weishi Mang, Adam Steimel

Together with innovatively applying modern flotation reagents and developing the breakthrough mill enterprise expert control and operating system, Doe Run Buick Mill constructed an advanced large copper rougher scavenger to process its complex Pb\Zn\Cu ore more efficiently. The scavenger circuit, featuring its own motor control center, air blower, multiple reagent loops and FrothSense+™ camera, operates both mechanically and chemically to maximize copper recovery and under expert control. Such scavenger features can be applied to zinc rougher circuits for all Doe Run mills to maximize Cu recovery during Cu special runs when the zinc rougher becomes a copper rougher scavenger.

Feb 1, 2025

By John H. Smith

Because of increased pressure from Federal & State Regulatory Agencies, most acid flows will require some sort of treatment prior to being discharged to receiving streams. In many industries, the volumes of liquors are large and their acid content varied. Pressure to minimize costs of waste treatment equipment and land usage makes development of a treatment process incorporating these desires mandatory. "Standard" methods of acid neutralization with lime have been known for years, however, the volume and characteristics of the resultant precipitated solids can create a disposal problem. Also, when standard lime treatment is used, the settling characteristic of the precipitated solids is normally slow. In some instances, the necessity of added dissolved solids removal, (such as iron, needing aeration) add to the problem of concentrating neutralized solids. In a paper published in the September 1970 issue of "Coal Age," *the results of extensive test work by personnel of the Homer Research Laboratories of Bethlehem Steel Corporation, Bethlehem Pa., were reported. This paper dealt specifically with development of a flow sheet to treat acid mine drainage (hereafter referred to as AMD) from coal mine operations. Regulations on discharged water required basic pH and low dissolved iron content after treatment. Liquid flows of over 9 MGD from

Jan 1, 1972

By Dan S. Nilsson

Small-scale mines are today expected to provide much of the increased production of metals, industnial minerals and coal this country demands in the future. But what is the size trend in the mining industry?

Jan 1, 1980

By T. T. Gronfors

The excavation process and equipment used for excavation join firmly each other. By changing the process or method, the construction of equipment may be altered essentially. It has been possible to develop a wholy new type of hydraulic boom for tunnelling, when only parallel drilling instead of V-cut is used. The utilization of controlled blasting has made small holes more desirable. So the controlled blasting has had an influence on the selection of drill steel equipment and in this way also influenced the construction of the equipment.

Jan 1, 1970

By A. K. Clarke

In any treatment process that requires a coarse feed material to be reduced to a fine size by crushing and/or grinding it must be determined whether a wet or dry comminution system should be utilized. All factors must be evaluated in reaching the decision. Among these factors are: 1) Ecology and Plant Environment: Unfortunately in many instances the decision on wet or dry is based on prejudice resulting from an unnecessary fear of dust. The writers submit that this fear, although once justified, is no longer valid because technology and equipment is now available to collect dust to meet any standard. When dry grinding is used it is very often possible to discard a portion of the waste product in a dry state. This will decrease the size of the tailing pond required. As pollution control standards increase it becomes increasingly difficult to clean up water from tailing ponds. 2) Operating Costs: Steel wear is often five or more times greater in wet grinding than in dry grinding. This is mainly due to corrosion. The evaluation of the economics of dry grinding must of course include the air system and dust collection; similarly in a wet grinding plant related pumping and material handling costs should be included. Pumping costs are often overlooked. This assumes water is made to flow for nothing. Pumping can account for 20 percent of the power consumption in the grinding plant. Large scale comparative tests were conducted in a wet and dry commercial plant in 1970. The same ore was used for both tests. With all factors included in both plants the dry system showed lower horsepower per ton.

Jan 1, 1971

By Kerry Gee, Gary Colgan, James Fricke

Introduction Elevated zinc concentrations are observed in groundwater within alluvium adjacent to Silver Creek east of Park City, Utah. The study area is located in a small valley one and one-half miles northeast of Park City, Utah in Summit County, Utah (Figure 1). Although surface water concentrations in Silver Creek are typically less than 1 mg/l, groundwater concentrations have been measured as high as 85 mg/l in a near neutral pH environment. The elevated zinc concentrations in groundwater result from several factors including: (1) dissolution of zinc from tailings exposed at the surface and within the alluvium, (2) oxidizing conditions created by surface/ground-water exchange, and (3) ideal geochemical conditions for the dissolution of zinc-containing minerals. These ideal conditions include readily soluble minerals, available anions for complexation, and lack of available surface adsorption sites.

Jan 1, 2005

By Frederick W. DeVries

The following charts were presented at the Randol Gold & Silver Forum 2000, held at the Hotel Vancouver (Vancouver, B.C.) from April 18-21, 2000. It must be borne in mind that the "facts" stated and con­clusions drawn by the author were not as the result of a rig­orous technical investigation, but rather as a member of a journalistic team seeking a rapid view for presentation as news to a TV audience. Since the author's visit, some retrenchment on the part of the operators on estimating the cyanide content of the spill seems to have occurred. This does NOT alter the conclusions that (a) the spill was an intolerable embarrassment for the world mining industry, nor (b) the potential damage to future mining investments, should prompt action not be taken: 1. to understand the reasons for the dam failure, and 2. to draw up firm concepts of how to avoid future fail­ures of dams at mining properties containing materials that are toxic, environmentally unfriendly, or with as highly dis­comfiting a profile as cyanide.

Jan 1, 2000

By E. -R. Niinikoski, M. A. Islam, H. Mischo, G. Barakos, J. Joutsenvaara, G. Meissner

European Union's transition to a low-carbon and digital economy highly depends on securing the strategic autonomy of the Critical Raw Materials (CRMs) supply chain. This paper introduces a European Commission-funded research and innovation action, AGEMERA, which aims to create detailed geological and people's concerns maps to unlock the CRMs potential in Europe. Furthermore, the project will develop educational packages for schools and universities, publish online CRM-related games and news flashes, and arrange public events to ensure a basis for socially accepted and sustainable exploration and mining of CRMs in Europe. 1. IntroductionCritical Raw Materials (CRMs), crucial for shifting to a low-carbon and digital economy, should focus on maintaining Europe's overall supply-demand balance (Birol, 2022). Therefore, to proactively address the surge in demand and ensure the strategic autonomy of European industrial supply chains, the exploration and extraction of CRMs must be scaled out across the continent. Moreover, mobilizing Europe's domestic potential is vital for the EU to become more resilient and to establish open strategic autonomy as the demand for CRMs continues to increase quickly on a global scale (European Commission, 2021). Base metal extraction and mining have a long history in Europe. Nevertheless, CRMs mining projects have shown less success, although these have a lot of potential (Guzik et al., 2021). The main barriers are a lack of investment in mining and exploration, complicated and drawn-out national permitting processes, and low levels of public support (European Commission, 2020). It is necessary to have a vast amount of knowledge and intelligence about CRM's potential and market impact. Novel non-invasive geophysical survey techniques that enable sustainable exploration must be created and used to enhance mineral system models of ore deposits incorporating CRMs. The minerals policy framework significantly influences the mining industry's performance, stability, and sustainability. However, the EU Member States' mineral policy frameworks differ significantly (MINLEX, 2017). In addition, the Fraser Institute Annual Survey of Mining Companies offers concrete information on how managers and executives of mining companies view key policy areas that impact mining activities in the jurisdiction in which they operate or are familiar (Jackson & Green, 2015).

Feb 1, 2023

By Odd E. Hanssen

In April 1982, the contracting Companies, ABV of Sweden and Hoyer-Ellefsen of Norway forming the Consorcio Escandinavo Agoyan, signed the contract for the construction of the civil works of the Agoyan Hydroelectric Project, located in Ecuador, South America. The project is located in the Andes mountain region of Ecuador - one of the smaller countries in this part of the world, located on the Pacific Coast. The contract was signed with the Instituto Ecuatoriano de Electrificación (INECEL), a public institution in charge of the development of all major energy producing projects in Ecuador, for a value of approximately US$ 120,000,000. The contract's main elements are - Concrete gravity dam with a total volume of approximately 210,000 cu m. (60 m wide x 45 m maximum height, 320 m crest). - 2,400 m of headrace tunnel, interior diameter of finished lining 6 m of which 450 m is in-situ tunnel formed in a trench. - Pressure shafts, 132 m long, the lowest meters with sheet lining, the rest with concrete lining. - Powerhouse cavern with an excavated volume of approximately 25,000 c m in which two turbines of 78 MW each will be installed. - Two 140 m tailrace tunnels with a finished diameter (concrete

Jan 1, 1985

By Charles T. Staniek

Following a dragline relocation at Agrico's Fort Green phosphate mine in 1986, the recovery plant experienced a significant decrease in flotation performance. Through weeks of trial and error testing, we discovered we could restore recoveries by conditioning feed at pH's higher than we had used historically. The higher pH's essentially increased flotation cell kinetics, although we still do not understand the exact mechanism at work. Armed with new-found appreciation of pH modification, we initiated a program to determine the optimum modifier for us, from both a performance and environmental perspective. Environmental considerations were important because ammonia, the standard industry modifier, is a plant nutrient and higher usage rates could affect the quality, of our recycle process water. This paper describes the research and development work spanning a 3 year period that culminated in making a major change in our reagent suite when we replaced ammonia with soda ash on a permanent full-time basis.

Jan 1, 1993

By Nigel Pearson, Malcolm J. McPherson

In the Grasberg Mine, a series of orepasses of diameter 2 to 4m are being constructed, each one to carry as much as 10,000 tlhour of copper- and gold-bearing ore through single stage vertical drops of over 500m. At the base of each orepass, the fragmented rock falls into an orebin of diameter 1 Om and 100m deep. Long before the planned tonnages were reached on the early orepasses, a problem arose that was both serious and intriguing. Pressurization of air in the orebins caused by the falling rock reached such levels that when the feed to the top of an orpass was interrupted, a massive surge of air ascended rapidly and produced a dangerous backblast accompanied by dust; grit and rock fragments from the top of the orepass. Backblasts lasted for about one minute and were not only hazardous to the health and safety of personnel but also required time-consuming clean-up operations. The paper describes the aerodynamic analyses that were con- ducted in order to understand fully the mechanisms involved in the phenomenum, and the development of a procedure that al- lows the effects of falling material to be incorporated into existing ventilation network software.

Jan 1, 1997

By Arthur W. Darby

Heathrow Airport is owned and operated by BAA who are engaged in a major programme of expansion. In order to link the expansion of the airport in the west with the existing central terminal area, a twin bore, 8.8m outside diameter, road tunnel,1280m long, is being constructed. The tunnel drives pass over, with limited clearances, an operating railway tunnel, and pass under, with about one diameter cover, the airport taxiways and aircraft stands. Selection of the machine was heavily influenced by the need to minimise settlement.

Jan 1, 2003

By Zachary D. Jones

"Construction projects involve a great many risks. The risk that material prices will increase during construction or that the work under construction will be destroyed by fire, storm or some other act of God are just a few examples. In tunneling or other underground projects, one of the most significant risks is that the subsurface conditions encountered during construction will differ from what is expected. Each of these risks must be accounted for, managed and, ultimately, the duty of one party or the other to bear. The primary tool used to allocate the risks among the parties is the construction contract.How construction contracts allocate the risk that subsurface conditions will differ have changed substantially over the past century. Today, construction contracts typically allocate the risk through a series of provisions. The first is the differing site condition or changed condition clause. That clause, when included, typically provides that the owner bears the risk that the subsurface conditions will differ from what is indicated in the contract documents or what is reasonably expected. The second clause is one that provides that the contractor must conduct a reasonable site investigation and bear the risk of any conditions that such an investigation would reveal. The third provision includes disclaimers that are often included in geotechnical data provided by the owner (or the owner’s engineer) to the contractor which attempts to limit the information on which the contractor can rely. Because these risk-allocating devices seem to be somewhat conflicting, a brief discussion of each provides critical insight in understanding how the modern construction contract allocates the risk of differing site conditions.At the start of the 20th century, construction contracts looked substantially different than they do today. For example, one contract for the construction of a public water tunnel in Chicago, IL, drafted around 1895 contained the following clause:The contractor must take the work entirely at his own risk. No extra allowance will be made for quicksand, hardpan or boulders."

Jan 1, 2014

By Michael Karmis

"In December 2011, the U.S. Attorney’s Office for the Southern District of West Virginia, the U.S. Department of Justice, Alpha Natural Resources (ANR) and Alpha Appalachia Holdings entered into a nonprosecution agreement related to the explosion at the Upper Big Branch Mine (UBB) that killed 29 miners. This coal operation was owned by Performance Coal Co., an affiliate of Massey Energy Co., which was acquired by ANR in June 2011, more than a year after the UBB explosion. Pursuant to the agreement, ANR agreed to:• Establish a trust within 120 days.• Pay a total of US$48 million into the trust to be used solely to fund and administer research and development (R&D) projects to improve mine health and safety.• Administer the trust by three highly qualified individuals with academic and/or professional backgrounds in mine health and safety.In April 2012, the Alpha Foundation for the Improvement of Mine Safety and Health was created. The three directors - Michael Karmis, president; David Wegman, vice presidenttreasurer, and Keith Heasley, vice presidentsecretary - approved a plan to expend both the interest and principal of the trust, aiming at an 8-10 year research horizon. The foundation also appointed David Belden, an experienced manager of nonprofits and professional associations, as the first executive director of the foundation. The IRS approved the foundation’s tax-exempt application, as described in Section 501c(3) of the Internal Revenue Code, on Dec. 18, 2012. The board established guiding principles of the foundation, which are as follows:• Mission: to improve mine health and safety through funding R&D projects to qualified academic institutions and other not-for-profit organizations.• Vision: to enable miners in the future to be free of work related injury or disease by the implementation of the results of the projects funded by the foundation and undertaken by the best researchers from any discipline that can contribute. The foundation is now approaching its third year and regularly posts updates, including semi-annual reports, to its website (www.http.alpha-foundation.org/), which serves as the main medium for communication with the broader stakeholder community"

Jan 1, 2014

By Jens Classen, Thomas Kurth, Karl G. Holter

High performance sprayed concrete equipment installed on two 9.4 m diameter hard rock TBMs enabled a continuous sprayed concrete lining for the entire contour in both tunnels to be performed concurrently with the advancing TBMs. Innovative layout of the sprayed concrete arrangements comprised ring beam constructions each with two independent spraying robots. Each of the spraying robots were independently connected to sprayed concrete pumps, as well as a high capacity concrete logistics system on the backup. The mix designs focused on long open-time, excellent pumpability and tough requirements on strength development. The achieved output capacities of the sprayed concrete amounts to an average of 15 m3 per hour. Peak capacities of 24 m3 per hour have been realized.

Jan 1, 2003

By Rolando V. Cuaño

For geostatistical applications, heterogeneous spatial phenomena are better modeled as mixtures of populations. However, the modeling of the constituent populations can become complex. The alternative mixture model offers a simplified approach to the w modeling problem. The model is applied and tested on the Walker Lake data set. Compared to the univariate ordinary kriging model, the alternative model generates less biased block estimates.

Jan 1, 1996

By Peter Hall

The need for large volume covered storage has increased drastically in the last ten years. Increased world demand for such products as thermal coal, potash, metallic concentrates, etc., availability of land for large open storage and environmental issues have brought about this need. This paper discusses briefly demand, environment, types of covered storage and the Alternative Storage System "Eurosilo", a proven system for storage of dry bulk mateials in units up to 100,000 m3.

Jan 1, 1982