Search Documents

By Carl C. Martin

The treatment of ores in preparation for fatty acid flotation is characterized by a wide divergence in methods, and attempts to define "common practice", even for the same type of mineral, are usually of little value because of the numerous exceptions. Such factors as desliming, pulp density, pulp temperatures, and reagents for conditioning are successfully employed under conditions representing almost extreme opposites. More precise control of variables is necessary than with sulphydric flotation processes It appears likely that variations result from independent development of a process from the multitude of variables that characterize fatty acid flotation and the ores of non-metallic minerals. Consequently, a symposium is a suitable way of presenting a summary of pretreatment methods for fatty acid flotation processes, together with froth control practices, as they exist today.

Jan 1, 1959

By Ping K. Di

A naturally aged and synthesized manganese oxide-coated granular media was found in our laboratory to have the capability of the removal of soluble Mn(H) from mine drainage by adsorption and oxidation. Mine drainage commonly also includes other heavy metal ions. Extending this principle, this paper presents the removal of heavy metals including lead, copper, cobalt, zinc and nickel in the aqueous solution by using the synthesized manganese oxide-coated granular media. It was found that the adsorption of lead, copper, cobalt, zinc and nickel on the manganese oxide-coated media follows both Langmuir and Dubinin-Radushkevich adsorption isotherms except in the concentration range less than 0.1 mmole/L. The adsorption mechanism involves the ion exchange between the heavy metal ions and synthesized manganese oxide coated on the media. The synthetic manganese oxide surface has a strong metal binding ability to the heavy metals in the order of Pb2+ > Cu2+ > Ni2+ > Zn2+ > C02+ based on the adsorption results using batch and continuous column operations. The breakthrough curves of these heavy metals showed that the synthesized media could be used effectively in the removal of these heavy metal ions in a cell or packed column. The process can simultaneously facilitate the immobilization of the heavy metals on the synthesized manganese oxide coated media. A subsequent pH adjustment dislodges the heavy metals and regenerates the synthetic media. Thus, the process accomplishes the adsorption, immobilization and concentration of the heavy metal from waste stream in one monolithic procedure.

Jan 1, 1995

By L. W. Laage

Throughout recorded history, underground fires have plagued mining operations. Compared with other hazardous situations in underground mining, a fire can become a global problem by swiftly spreading deadly carbon monoxide and other products of combustion (POC's) throughout the whole mine, often without warning. Experience has shown that when fires are detected and located in their early stages, they are much easier to control and proper escape routes can be more intelligently selected. Recent advances in sensor and data communication technology have made reliable mine fire .detection system installations possible. Unlike building construction. in a mine, it is impractical to install detectors at every desired location. Abandoned workings and unsafe locations preclude sensor installations from both safety and economic standpoints. The net effect is that some fires are detected and located early while the location of others, even if detected early, remains unknown too long for effective evacuation and fire fighting.

Jan 1, 1989

By J. `. Spitzinger

In situ recovery (ISR) of uranium alters the baseline groundwater geochemistry in order to mobilize and complex uranium to extract and concentrate it. ISR wellfield restoration is often challenging, and primarily relies on groundwater sweep, reinjection of treated permeate, and/or injection of reductants. Greater focus should be placed on injection-based approaches (using existing infrastructure) based on established engineering concepts used for in situ remediation of groundwater plumes. Such injection-based approaches could shorten restoration timeframes consequently reducing long-term operational costs. This paper addresses various types of injection-based approaches to wellfield restoration based on in-situ remediation success with other constituents that require similar treatment. This paper describes necessary design practices for injecting reactive chemicals (e.g., reductants or biostimulants), operations and maintenance (O&M) strategies to prevent fouling of the chemical delivery system and well network, and natural constraints to restoration. Best practices for successful biostimulation strategies that minimize residual uranium, radium, oxoanions, and other trace elements are as described. Advantages of such injection-based approaches could include significant reductions in restoration times, and consequently, lower restoration costs.

Feb 23, 2014

Design models for belt conveyors used in mines predict both the belt power requirements and belt tensions. Conveyors with slightly downhill profiles are more complex to predict due to the way that models such as CEMA interpret friction. Performance of a particular conveyor in relation to other conveyors in the same system requires an analysis of natural stopping times, braked times and take-up location. A review of CEMA-based PC models is presented for design of underground multi-flight belt systems.

Jan 1, 1995

By Blake M. Paterson

The increasing global demand and lower price of gold has resulted in more advanced gold extraction techniques. One trend is the use of oxygen in place of air in the leaching process, which is proven to significantly enhance recovery of gold ore refractory in such techniques as CIP and CIL. This has resulted in a search for more reliable and cost efficient paradigms of oxygen supply. Many gold mines already realize the heightened recovery rate achieved with oxygen. Previously this benefit had only been available to the largest consumers of oxygen, near oxygen production facilities. Requirements of (1) to (20) metric tons per day have traditionally been supplied with expensive, delivered, liquid oxygen. Since many mines are located in remote areas, it is difficult to secure cost effective and continuous supply of liquid oxygen. However, the benefits of On-Site Oxygen Production combined with a self-generated bulk reserve supply are now available to mine sites. This paper explains and discusses the use of on site Pressure Swing Adsorption (PSA) oxygen production, coupled with a cryogenerator to liquefy oxygen for storage. This package offers continuous oxygen supply to mining sites in even the most remote corners of the world.

Jan 1, 1997

By Marian Radetzki

The economic developments and industrial behavior patterns that led to a lasting excess capacity in the world non-ferrous metals industries from the aid-1970s are explored. Detailed attention is devoted to analyzing and defining crucial concepts like "capacity", "excess capacity", "capacity maintenance" and "investments". Empirical evidence of capacity utilization and capacity growth in the industries under study is provided. The coincidence of excess capacity and low prices on the one hand, and investments in capacity maintenance and capacity expansion, on the other, is seen as a consequence of substantial declines in the metal industries' investment and production costs during the period studied.

Jan 1, 1989

By Shiou-Chuan Sun

Notwithstanding the fact that unsaturated fatty acids are used in preference to saturated acids for most flotation purposes, information regarding their collecting properties is sketchy. Keck, Eggleston, and Lowry1 reported in 1939 that the collecting power of fatty acids on hematite decreased in the order of oleic, lauric, myristic, palmitic, and caprylic acid. Keck and Jasberg2 described in the same year that "unsaturated oleic acid with 18 carbon atoms was a better collector than saturated stearic acid" for floating magnetite. Gaudin and Cole3 stated in 1953 that the double bonds of oleic and linoleic acid were not oxidized during the flotation of fluorite, whereas the double bonds of linolenic acid were measurably altered even after one single flotation step. In August, 1953, Hukki and Vartiainen4 concluded that the collecting power of palmitic, oleic, linoleic, and linolenic acids on ilmenite, magnetite, pyrite, and rutile increased with an increasing number of double bonds in the acid molecules. This was subsequently proved to be generally true for the flotation of mapganese5, phosphate6, and magnetite7. The above cited literature indicates that, prior to the present paper, only about ten minerals were tested with pure unsaturated fatty acids as collectors.

Jan 1, 1959

By E. J. Meets, C. F. Meyer

Bord and pillar mining at shallow depth (400 m approx. maximum) is widely used in South African coal mines. One of the problems encountered in extracting coal in this manner is the ventilation of advancing bord and pillar headings. The traditional ventilation methods of force, exhaust and overlap (force/exhaust) are reasonably effective but tend to be both cost and labour intensive. Ducting often restricts the available free area of roadways thus impeding the transport of coal and other materials inbye the coal production section. Due to the above facts, ductless fans are currently being used to minimize the amount of ducting required in advancing sections. Two different types of fans are used, namely, vortex fans and the so-called `jet' fans. Vortex fans were developed from the fan blade design used for vertical take-off aircraft. The fans have the capability of delivering air over distances of about 30 m in the underground situation without any ducting attached to it. Jet fans are standard axial flow fans fitted with outlet reduction pieces which increase the velocity pressure at the discharge to such an extent that the air delivery distance is improved to almost match that of vortex fans. The paper describes some applications of both these fan types in advancing bord and pillar sections.

Jan 1, 1993

By M. Javier

This concept paper is presented in the hope of raising the awareness of mankind on the necessity for its peaceful coexistence with nature. It is a food for thought. It takes compromise and sacrifice of people, who will have to learn to curb their greed and move toward a more organic form of prosperity. A nature-friendly sustainability is first step toward the protection of nature that is critical to the mutual survival of mankind and nature. People need the resources from the finite earth to survive and nature needs the prevention of human destruction in order to continue to regenerate and provide. The contemporary notion of sustainability is self-serving. It serves the interest of industry by camouflaging itself to look like nature?s protector. The ?sustainability? concept presented in this paper aims to extend the longevity of the utilization of the limited natural resources for many generations to come. It is an important, responsible first step in creating a healthy sustainability concept that, when implemented, extends the longevity of mankind by the most efficient use of the finite resources on this limited Planet Earth, all the while taking into consideration the increase in anthropogenic activities due to exponential human population growth. This new definition of ?sustainability? has completely different characteristics than its contemporary versions. Nature has its own destiny, rules and principles. Being a part of nature, human society depends on it for survival and must play by its rules and never the other way round as in its initial pretensions. Society should not try to humanize nature, but rather to respect the rule of the nature in a peaceful way of co-existence. When implemented, this new concept of sustainability aims to affect the designs of engineered structures and revolutionize the recovery methods and processing of natural resources, such as mineral resources in the most efficient manner. Finally, this paper intends to stimulate critical thinking and initiate serious discussions aiming at producing a general consensus for the best definition for human society to not only enrich, but to extend its existence. Thus, the spirit of this new definition is pro future generations and environment. KEYWORDS: Sustainability Definition, Nature, Geomímic, Deproduction.

Feb 27, 2013

By William Gleason

"The city of Denver, CO has experienced extreme growth in the past decade, with the population of the city topping more than 700,000 people in 2018. The current storm water drainage system was put in place in the early 1900s and has not been able to keep up with the growth of the city.When it rains north and east of the city, the runoff goes toward the South Platte River. With the dense population and sometimes severe thunderstorms in the summer, the city has experienced significant flooding that not only endangers lives of residents, but some of the storms have caused millions of dollars of property damage.The Platte to Park Hill Project is a $298-million nearterm, four-phase solution to the flooding that includes the Globeville landing outfall; an open drainage project in the Cole neighborhood in north Denver; an area for temporary water detention and another temporary water detention in Park Hill.The largest and most complex phase of the project is the Globeville landing outfall — a $70-million box culvert project that includes a pair of 157-m (515-ft) long, 243-cm (96-in.) diameter storm water tunnels that pass beneath a busy rail yard with 17 tracks for the Union Pacific Railroad (UPRR) and two Regional Transportation District (RTD) commuter rail tracks. The tunnels, which were installed parallel to a pair of existing 243-cm (96-in.) tunnels, were designed by Brierley & Associates as a client of Merrick & Company for the City & County of Denver, and Bradshaw Construction constructed the one-pass tunnels.From the start, it was evident that the tunneling portion of the project would be the most challenging because of the rail yards.“It’s a little bit more complicated because the railroads have such tight restrictions for settlement,” said Rebecca Brock, Brierley’s project manager. “We had a lot of meetings with Union Pacific and RTD to figure out what are prescribed versus tolerable settlements.”“The portion extending beyond the UPRR under the RTD rails was challenging, as RTD is new to tunnel installations under its tracks,” said Lester Bradshaw, president of Bradshaw Construction. “The RTD tracks employed a unique foundation of continuous concrete with integral raised concrete ties on rubber bushings. Minimizing settlement to these tracks was a critical requirement.”"

Jan 9, 2018

By Norbert Patzelt, Hans Knecht, Wolfgang Baum

Future ore reserves of major gold producers in North America and elsewhere will consist of refractory gold ores. About 60 % of the current U.S. gold production is mined in Nevada. Several of the large gold operations in this state indicate that 40 to 90 % of their future ore feeds will contain refractory gold. To compound problems, average head grades for refractory U.S. gold ores have fallen from 8 - 9 g/mt to about 4 g/mt by 1991. In Latin America, 52 % of the gold operations will require milling for optimal recovery. Deeper reserves are, like in North America, refractory. Particularly in hard, (semi)refractory sulfide ores, many operations may experience substantial decreases of gold recov­ery. For example, Martins et al. (1991) report that at an Austra­lian mine, sulfide ore treatment led to 4 - 10 % lower gold reco­veries as the work index increased from 8 kWh/t to 14 kWh/t and the grind coarsened. Many refractory ores should actually be classified as semirefractory since a fine sulfide fracturing and liberation would make 80 - 90 % of the gold cyanide leachable. However, conventional comminution is often prohibitively expensive for these ore types.

Jan 1, 1995

By D. J. Wood

BHP Copper has grown, in just over six years, from a minor participant to the world's largest privately owned copper producer. BHP Copper's major asset is the world's largest copper mine -Escondida in Northern Chile. Ten years ago investing in Chile was considered high risk. Today, Escondida represents an investment of approximately US$2 billion. Reward is the result of managed risk and Escondida is a clear demonstration of both. The Ok Tedi copper and gold mine in Papua New Guinea represents a Rubicon of risk and a retrospective on reward in a developing country on the doorstep of a developed one. The story of these two mines encapsulates risk in the mining industry.

Jan 1, 1998

"INTRODUCTION While the United States coal mining uses prescriptive regulation under the Title 30 Code of Federal Regulation enforced by the Mine Safety and Health Administration (MSHA), Australia uses a risk based approach. Australian regulation is individual to each state. In Queensland, Australia this risk based approach to address principal hazards is underwritten by the Queensland Coal Mining Safety and Health Act of 1999 and the Coal Mining Safety and Health Regulation of 2001. Each Queensland Mine is required to have an overarching Health Safety and Environment Management System, of which Safety Management Plans are an element. “Safety Management plans (SMP’s) are intended to formalise the process by which mines address principal hazards and other related matters to ensure the safety of mine personnel.”7 THE QUEENSLAND CONTEXT In Queensland, the basic elements of a coal mine’s safety and health management system must provide for risk identification and assessment, hazard analysis, hazard management and control, and the reporting and recording of relevant safety and health information and data.5 (Part 2 Division 1 Section 6(a-d)) The initial guidance for writing Safety Management Plans comes from the Approved Standard for Mine Safety Management Plans and Guidance Note QGN09- Reviewing the Effectiveness of Safety and Health Management Systems. The Guidance Note and Approved Standard are supplemental to the Act and Regulation, and put in place to provide more clarity around the topic. The definitions in this section come from the Approved Standard and are included to provide context for those who may not be familiar with Australian or Queensland law and regulation. A hazard is defined as a source of potential harm or a situation with a potential to cause loss, while a principal hazard is a hazard with a potential to cause multiple fatalities. A risk is the chance of something happening that will have an impact upon objectives which is measured in terms of consequences and likelihoods. It is important to be able to make the distinction between a hazard and a risk. For instance, a lion is a hazard, while the risk associated with a lion is getting eaten. As defined by the Queensland Approved Standard for Mine Safety Management Plans, a Safety Management Plan (SMP) requires a systematic definition of all the actions necessary to ensure that mining operations are carried out safely. A SMP includes, but is not limited to organisational structures, planning, activities, responsibilities, practices, risk identification, audits and reviews.7 The goal of a SMP management plans is to mitigate the risks to bring them to an As Low As Reasonably Achievable (ALARA) level."

Jan 1, 2016

By Rameshwar Sah, Somasekhar Pitchika, Akhil Singh, Seenivasan Rajiah, C. B. Dayanand, G. Balachandran

In the sintering of iron ores, the partial substitution of anthracite coal for coke breeze has been considered to be an effective way of reducing emissions and improvement in sintering properties. In the present study, the combustion characteristics of the anthracite coal and coke breeze were investigated and its influence on product sinter quality and sinter flue gases is being monitored. Pot trials are carried out with different coke breeze ratios, 0%, 40%, 50%, 60%, and 100%. It is found that as the percentage of anthracite coal is increased from 0 to 100%, the sintering time decreased from 24 to 20 min, and the productivity increased from 2.25 to 2.60 t/h/m2. Up to 60% anthracite coal substitution Tumbler index (+ 6.3 mm%), Product yield (+ 5 mm%), and fines generation (− 5 mm%) is found 62.29%, 85.17%, and 15.33%; moreover, hematite ( Fe2O3), magnetite ( Fe3O4), calcium ferrite phases ( CaFe2O4, CaFe3O5), and Silico ferrite of calcium and aluminum (SFCA) are major mineral phases found during microstructural analysis of product sinter. Keywords Sintering · Anthracite coal · Combustion rate · Productivity

Jun 2, 2022

By Lloyd C. Venburg

Analytical and computer models are used to evaluate information obtained for the design and development of mine water control systems. Geologic, hydrologic, geophysical, biological, and chemical data must be gathered for use during all stages of mine development. Models allow the geohydrologist to use these data to predict the amount of ground-water inflow, the impact of dewatering and stream diversion on the hydrologic regime, equipment needs, and dewatering schedules. Stratigraphic and lithologic changes, faults, recharge and discharge areas, and aquifer parameters should be incorporated into the model to design and develop an effective mine water control system.

Jan 1, 1982

By Refik Elibay, Lawrence A. Williamson, George D. Barnes

Under an extremely aggressive schedule, final design of 13.5 km (8.4 miles) miles of 8.2 m (27 ft) diameter deep rock tunnel, 322 ML/day (85 million gallons / day)submersible pumping station and associated facilities were accomplished ahead of a federal court mandated consent decree schedule. Challenges overcome by the project team in enabling timely completion of the construction documents will be presented. Discussion includes evolution of final design, consideration of future O&M requirements, and risks identified for construction and operations, together with measures to manage and proactively prepare for such risks.

Jan 1, 2005

By T. A. E. Breen

A new high intensity grinding technology has been developed and is now being commercialized by Hicom International of Australia. This has led to the development and manufacture of Hicom 120 grinding mills which are now being sold internationally for a range of mining industry applications. The first commercial process application has been for the diamond sector, where the ability of the mill to remove host kimberlite rock by attritioning, with no damage to the thereby liberated diamonds, is seen to be a most beneficial attribute. There are, however, many other mineral industry applications for this mill. The design of the Hicom mill is unique. Based on a high speed centrifugal motion of the grinding chamber, very high power intensity is delivered to the grinding process. Most significantly, a high acceleration field, 50 times stronger than gravity is produced, creating very high power input per unit of mill volume, and exceptionally fast particle breakage rates, typically 50 - 100 times greater than those in conventional tumbling mills. A mill developing such forces has significant implications to comminution technology and practice.

Jan 1, 1999

By Neil White

South Africa (SA), a country in which all three commercially important asbestos minerals have been mined and milled, has retained proven cases of mesothelioma linked with environmental exposure to asbestos. This study illustrates the importance of fiber type in the occurrence of environmental mesothelioma. Four studies have reviewed the source of occupational or environmental asbestos exposure in 504 histologically proven cases of mesothelioma in South Africa. One hundred and eighteen cases (23%) were thought to be related to environmental exposure to asbestos. In the vast majority of these cases, exposure was linked to crocidolite mining activities in the Northern Cape Province. Two cases were thought to have occurred in relation to amosite and Transvaal crocidolite exposure in the Limpopo Province. In the balance of cases there was some uncertainty. No cases were reported with exposure to South African chrysotile. Consequently, in the vast majority of cases of mesothelioma, environmental exposure to asbestos occurred in the Northern Cape Province, in proximity to mines, mills and dumps where crocidolite was processed. Crocidolite appears to be far more mesotheliomagenic than amosite, and chrysotile has not been implicated in the disease. This is true for both occupationally and environmentally exposed individuals. ©2007 Elsevier Inc. All rights reserved. Keywords: Crocidolite; Mesothelioma; Chrysotile; Amosite; South Africa

Jan 1, 2007

By D. Kwietnewski

With all of the unknowns associated with tunnel construction, how does a contractor choose a roadheader? This paper presents a review of several models of roadheaders being used in today?s tunnel projects. The features of different models of roadheaders are presented and compared. Roadheader size and cutter power generally determine which roadheader is best for a particular job. We will also present a model for matching features of the roadheader to the anticipated ground conditions such that the most efficient machine is selected for the project.

Jan 1, 2011