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By Mark Colwell

As per most other earth science engineering problems, the underground coal geotechnical environment and the way in which roof and rib support interacts with the rock mass are complex issues. While the problem should not be oversimplified (i.e., the dominant failure mechanisms or critical data input parameters should not be ignored), without question judicious simplification is at the heart of all good engineering design. Engineers play a vital role in supplying the world with solutions and products; however it is crucial that engineers make practical and readily useable contributions. One way to ensure this is to employ simplification in the engineering process.

By Chee Theng

"Mineral processors know you can put in the best technology in the world but it won’t work optimally without the support of the operators. Conversely, you may have complete operator support but won’t get top results without the right technology. When the two come together, the returns can be phenomenal.The first day of talks at the 68th Annual Colorado MPD Conference, held April 26-28 at The Broadmoor in Colorado Springs, covered the ground on these industry wisdoms.Coming together as a team“Think of the people, not just the lab and the numbers. That makes all the difference,” said Dee Kippers, of FMI Henderson Mine, in her talk on “Process optimization during a market downturn (A Moly MacGyver story).” Kippers told an entertaining story of the journey she and her team took in tackling the issue of an annual spike in iron content in the product at Freeport- McMoRan’s Henderson primary molybdenum mine near Empire, CO.As the metallurgists tried one thing after another — cranking up the iron depressant, adjusting pH with sodium hydroxide and hydrated lime, modifying reagent levels — Kippers found that when she shared her results with the operators, communicated with them on what she was doing and got their input, they were more willing to work with her, and more understanding and supportive of her efforts.The results make the case for getting people on board and coming together as a team. The cost savings from their optimization efforts, with little capital investment, have been “enough to cover the annual salaries of our metallurgy department and then some,” Kippers said.Considering the environmentDavid Lemieux, of Dundee Sustainable Technologies (DST), talked next on “Cyanidefree process for gold extraction,” presenting the results obtained from a demonstration campaign of the company’s novel chlorination process for gold extraction and associated arsenic stabilization process. Developed at an investment cost of C$35 million, they are ready for commercialization, having been demonstrated on the laboratory, pilot and demonstration scales.The DST process is differentiated from the Plattner chlorination process, which was in use from 1851 to 1916, by moderate process conditions of atmospheric pressure and ambient temperature — the result of using sodium hypochlorite solution, or bleach, instead of direct injection of chlorine gas — and new, cheaper materials of construction, such as polymers, plastics, fiberreinforced plastics and Teflon, resulting in lower capital and operating expenditures."

Jan 7, 2018

By M. R. Shahan, C. E. Seaman, Mischler S. E., T. W. Beck

"Float dust deposits in coal mine return airways pose a risk in the event of a methane ignition. Controlling airborne dust prior to deposition in the return would make current rock dusting practices more effective and reduce the risk of coal-dust-fueled explosions. The goal of this U.S. National Institute for Occupational Safety and Health study is to determine the potential of open-air water sprays to reduce concentrations of airborne float coal dust, smaller than 75 µm in diameter, in longwall face airstreams. This study evaluated unconfined water sprays in a featureless tunnel ventilated at a typical longwall face velocity of 3.6 m/s (700 fpm). Experiments were conducted for two nozzle orientations and two water pressures for hollow cone, full cone, flat fan, air atomizing and hydraulic atomizing spray nozzles. Gravimetric samples show that airborne float dust removal efficiencies averaged 19.6 percent for all sprays under all conditions. The results indicate that the preferred spray nozzle should be operated at high fluid pressures to produce smaller droplets and move more air. These findings agree with past respirable dust control research, providing guidance on spray selection and spray array design in ongoing efforts to control airborne float dust over the entire longwall ventilated opening. IntroductionCoal mining processes produce airborne dust that naturally deposits on the floor, roof and ribs of mine airways. These fine dust particles, termed float coal dust when smaller than 75 µm in diameter, are deposited in the return entries of coal mines and can be reentrained by pressure waves induced by methane-air explosions (Rice et al., 1911; Nagy, 1981; U.S. National Institute for Occupational Safety and Health (NIOSH), 2006). These particles are also those most likely to participate in coal-dust-fueled explosions, which can potentiate and propagate explosions resulting in extensive damage. In order to meet compliance requirements of at least 80 percent incombustible content in the composition of material deposited in mine entries (U.S. Mine Safety and Health Administration (MSHA), 2016), coal mines apply an inerting agent, specifically, rock dust (Harris et al., 2009). Should methane be present in the mine atmosphere, the required fraction of incombustible content is further increased by 0.4 percent for each 0.1 percent methane. The removal of airborne float coal dust (AFCD) prior to deposition is an approach intended to make current rock dusting practices more effective by increasing the proportion of inert material to combustible material, resulting in a lower risk of coal-dust-fueled explosions."

Jan 1, 2018

The mineral sands industry is oriented primarily toward the supply of titanium (Ti) raw materials (titanium feedstocks) for the production of titanium dioxide (TiO2) pigment and titanium metal. Titanium minerals ilmenite, rutile and leucoxene, and titanium slag and synthetic rutile are all used principally as feedstocks for the production of white TiO2 pigment. It accounts for almost 90 percent of the world?s consumption of titanium minerals. The remainder is used for the production of titanium metal, fluxes for welding rods and as a metallurgical flux in iron and steel making. Titanium dioxide pigment is produced by two alternative process routes, the sulfate process or chloride process. The bulk of the world?s titanium dioxide is derived from the mineral ilmenite, which also contains iron oxide and other minor impurities. At some mining operations, the iron present in ilmenite is removed (ilmenite beneficiation) to produce a high TiO2 feedstock (slag or synthetic rutile) typically containing between 80 percent and 95 percent TiO2. Pigment producers then further process it to produce pigment.

Jan 1, 2011

By K. Vanbroekhoven

An industrial site near the centre of a historical town in Flanders is characterized by chromium(VI) contamination of the groundwater. Since the potential for natural attenuation was not sufficient to control the groundwater plume as observed from different analyses like pH, Eh, soil oxidation and reduction capacity, the feasibility of site remediation based on in-situ bioprecipitation of chromium was examined in lab microcosm studies. By creating reducing conditions by addition of a carbon source in the groundwater, chromium(VI) can be biologically reduced to chromium(III), which can form an insoluble precipitate of chromium(III) hydroxide. Microcosms contained contaminated groundwater and aquifer samples that were collected and manipulated under anaerobic conditions. Three different carbon sources were screened for their effectiveness: molasses from sugar beet production, molasses form starch production (protamylasses) based on potato juice and lactate. The different concentrations of sugar molasses were used to determine the optimal conditions. A range of parameters was monitored at regular time intervals for a period of six months such as chromium(VI) and chromium(III), DOC, methane, pH, Eh. A rapid conversion of chromium(VI) to chromium(III) was observed for all conditions tested. However, extensive removal of chromium from the groundwater by precipitation was only achieved for a limited number of conditions. In general, lactate was found to be the most effective carbon source, slightly better than the lowest concentration of sugar molasses that was tested, which itself was more effective than molasses based on potato. Higher concentrations of molasses, although causing a steeper decline in redox potential, resulted in less effective Cr removal. Typically, the fermentation of molasses results in acidification and this drop in pH may hinder the formation of insoluble chromium(III)hydroxides. It may also be possible that certain components of the molasses form soluble complexes with chromium(III). For lactate, no significant drop in pH was observed. Following the laboratory microcosm tests, the stability of the chromium precipitates was examined by performing a sequential extraction on the microcosm materials. These were performed under redox conditions which were similar to the ones observed in the field. Since the outcome of these tests was positive, a pilot scale test was implemented in the field in April 2005. Two different substrates, the cheap waste product sugar molasses and lactate are being injected creating two different impact zones and typical parameters are monitored. Frequent re-injections were important to maintain reduced conditions and are carried out three-weekly up to now. To study the stability of precipitates formed, mesocosm socks containing aquifer material were installed in the monitoring wells and harvested at regular intervals. Results of this pilot test will be presented and compared to the laboratory results. Based on the success of this field test, a full scale process will be designed and implemented as remediation strategy.

Jan 1, 2006

By Andrew B. Cecala, Emily J. Haas, Jay F. Colinet

A sociotechnical system (STS) creates a framework that allows an examination of how social and technical factors affect organizational outcomes within a specific environmental context. STS has been rigorously studied with a primary research focus addressing worker-technology interactions. Although these interactions are important, the social processes and interactions that occur whenever any technical or environmental change is introduced into the system have been undervalued. If social processes are better understood, mining organizations could efficiently prepare and stabilize for such changes. With this goal in mind, we sought to extend STS theory through applying principles of meta-design to analyze the results of two case study interventions. Specifically, we studied the impact of an unregulated dust control technology (the Helmet-CAM) and a regulated dust control technology (the Continuous Personal Dust Monitor) on factors within an STS including employees’ knowledge of, communication about, and use of technology to mitigate respirable dust sources. The results are presented in a way that first, addresses the overarching principles of meta-design STS including organizational participation, flexibility, and communication and second, examines how technology implementation processes differ when the organization is complying with a formal, higher-level requirement. Results show that a prominent focus on the social factors within an STS framework could help reduce unpredictability on the technical side and may improve communication within the system to help reduce adoption time, especially if and when accompanying a new, formal work process.

By G. M. Bernard

The Andacollo gold mine is located near the small town of Andacollo, Chile (population 14,000) in the fourth region. It is approximately 35 miles by paved road from the coastal city of La Serena, and Santiago lies about 300 miles to the south (see map.) Site elevation varies between 3300 feet and 4200 feet. The climate at the site is moderate but arid, with an average annual rainfall of only five inches. Because there is little rain, and the temperature varies only a few degrees (57"F to 75°F); there are no freezing, solution dilution, or pad saturation problems. The climatic conditions are ideal for heap leaching.

Jan 1, 1996

By R. L. Miller

"Miners worldwide use a tremendous amount of energy in producing finished minerals for the end user market. In accomplishing this goal, they incur energy costs that can range from 20% to 30% of the total cost of production, so there is fertile ground for cost savings. To unlock this huge value in cost reduction, energy analysis is the key and is broken into several segments: 1. Fuel analysis for power generation 2. Energy supply & demand 3. Opportunity cost for lack of power 4. Backup power 5. Power contracts 6. Energy efficiency 7. Renewable energy 8. Continuous energy management FUEL ANALYSIS FOR POWER GENERATION What is the first thing we evaluate when looking at power supply alternatives for the mining industry’s large power requirements? Is it 1) site, 2) engineering, procurement, and construction companies, 3) independent power producers, 4) turbine vendors, 5) grid connections, or 6) fuel supply, logistics, and infrastructure? In evaluations of power supply alternatives for mining companies with special emphasis in developing countries, there is one over-riding conclusion: reliable fuel supply drives the energy generation economic engine. Evaluating several different fuels including liquefied natural gas (LNG), natural gas, diesel, heavy fuel oil, and liquefied petroleum gases (LPG) among others, the best project outcomes are those where fuel supply, pricing, logistics, and infrastructure are given an extensive amount of time during the analysis stage. In an assessment of the twenty-year costs of generating power from multiple fuels, each fuel’s costs were placed into three separate net present value (NPV) buckets of: 1) capital, 2) operating and maintenance, and 3) fuel. Within a range of 65% to 85% for all fuels, fuel cost was the largest component of the NPV of the life cycle power generation costs. So if 65% to 85% of your life cycle power generation cost is one item, shouldn’t miners spend a corresponding amount of time in the analysis stage fully understanding this key determinant for a successful power project? In developing countries where power generation infrastructure may not exist or does not exist at the same level as is found in North America and Europe, fuel analysis becomes even more important. One of the key questions for fuel importation in developing countries is the draft at existing ports to allow larger vessels to dock at the jetty. Can larger ocean-going tankers dock at the port for off-loading, or is the port’s draft too shallow, thus forcing a Single Point Mooring (SPM) system or Conventional Buoy Mooring (CBM) system to be constructed at substantial capital expense? Once fuel can be imported, sufficient onshore storage capacity should exist, or must be built to off-load the entire fuel cargo from the larger ships. Additionally, the throughput capacity of the pipeline from SPM/CBM must allow a rapid unloading of the fuel from ship to shore to eliminate steep demurrage costs for the project."

Jan 1, 2017

By George L. Wilhelm

Timber support of mine openings continues to be an effective system for ground support, due to its avail¬ability, flexibility, and ease of installation. Timber support of mine openings as a primary method to support loose rock has been replaced to a large extent by rockbolting and by filling systems. How¬ever, the many designs of square-set timber and varia¬tions of crib and stull support that have been developed to suit many stope configurations have proven reliable over many years of application. Integrated in modern excavation and stoping methods, timber remains an im¬portant ground support material for today's mines. ADVANTAGES AND DISADVANTAGES OF TIMBER SYSTEMS Timber, when used as a part of the total support system, is recognized for its unique support properties. More than a cover to prevent minor falls of ground, timber systems have been carefully designed to provide adequate support with sufficient compressive qualities to achieve a safe working environment in extremely diffi¬cult ground conditions. In some cases, a timber support method is designed to yield while retaining its protec¬tive support qualities. Little or no initial investment in equipment or plant is required for incorporating timber into the mining support system. Low cost cutoff saws and portable chain saws are sufficient equipment for effective use of dimen¬sioned (sawed) or round (stull) timber support. Until recently, small sawmills of various complexity were com¬mon at mine surface plants. Sawmills at the mine sites have generally been replaced by timber vendors' mills. Suppliers have been able to use efficient cutting and lumber handling methods to reduce the cost of mine timbers. Most suppliers will package dimensioned mine timber into bundles that are suitable for handling down mine shafts and on level conveyances. The principal disadvantage of timber as a support method is higher material cost and labor cost associated with its labor-intensive installation. Furthermore, stand¬ing timber reserves of mine quality wood are in short supply in some areas, and heavy competition exists for alternative uses of the timber supplies. Vendors are reluctant to supply large cross section dimension tim¬bers relatively free of defects. Some mine operations require 4.8-m (16-ft) lengths of firm timber over 0.09 m2 (144 sq in.) in section and these are difficult to obtain in large quantities. APPLICATION OF TIMBER FOR MINE SUPPORTS Timber used in mine support has been cut from many species of trees. A firm hardwood with physical properties similar to western Douglas fir has been pre¬ferred in the US. Other harder and softer woods, how¬ever, have been used when readily available or where the specific strength or crushing quality of the wood is a desired specification of the support system design. Hard¬ wood, commonly oak, has been used where maximum crushing resistance is required. Mahogany and fir are widely used for shaft guide timber. Normally, timber is used with its core axis parallel to the long axis of the timber dimension. However, in some cases, it is placed normal to its core in a "butt" log position, so as to provide maximum resistance to abrasion of the ore passage adjacent to the cut end of the block. By selective placement of timber block¬ing, controlled resistance to ground closure can be achieved which will prevent early failure of primary sup¬port members of the timber structure. Timber is widely used in modern mining operations as a construction member for chute-lip support. These designs are tailored to each operation to conform to the dimensions of the haulage equipment being used. As a construction material, wood requires none of the spe¬cial equipment necessary for placement of concrete or steel support. Placement of these alternate support ma¬terials requires carefully dimensioned and engineered excavation for their installation. Wood can be easily sawed to fit on location. The successful use of timber in heavy ground de¬pends on the careful and accurate placement of block¬ing and bracing to achieve the controlled yielding re¬sistance needed to support the mine opening. Similarly, frequency, size, and placement of top and bottom block¬ing stulls in flat-bedded deposits are carefully determined to provide adequate support at the mining face. Con¬trolled caving through failure of the stulls may be required as the scope retreats from the earlier mined-out sections. The support program must achieve both of these dimensionless qualities by specification of stull frequency and size. The utility of the square set-system of ground sup¬port and timber support is described in Chap. 2, re¬printed from US Bureau of Mines Information Circular 6691. Four examples of effective use of timber for support of stoping and other mine openings are pre¬sented in other chapters in this section. The Gilman mine's use of Mitchell slice stoping described in Chap. 3 is an early modification of the square-set mining system. This application proved reli¬able for heavy ground and overcame some of the dis¬advantages of conventional square-set timber. Chap. 4 describes the Burgin mine's use of timber with other reinforcement material. This combination of materials achieved high strength and control with yielding com¬ponent members necessary for heavy, squeezing ground. Chap. 5 describes the Bunker Hill mine's use of square¬set timber in a new configuration that provides an effi¬cient and safe support for stoping using small load¬haul-dump (LHD) mobile equipment. Chap. 6 describes some considerations in placing the widely used stull in bedded ore deposits. Finally, in Chap. 7, cost calcula¬tions for

Jan 1, 1982

By John W. Crawford

The title of the paper which I have been asked to present is somewhat misleading it infers in fact that there is a definite coalbed height below which raps or canopies cannot be applied to electric face equipment. Although this may be so with regard to certain pieces of existing equipment under certain conditions, to date we do not have enough experience to determine this magic number. Therefore MESA is continuing to hold the line on the time frames stipulated in Section 75.1710-1 of the Mandatory Safety Standards - Underground Coal Mines, which at this point in time requires these protective structures in mining heights of 60 inches or more. In order to give you an idea why we are taking such a firm stand on this matter, I believe it is necessary to describe some of the background work that was done prior to promulgation of the regulations and to give a resume of our experience since the requirements have become effective. Initially MESA made field investigations of all underground mines to determine what the state of the art was in the use of cabs and canopies for protecting equip¬ment operators from falls of roof. These studies revealed that the application was basically in its infancy and what progress had been made was due to the impetus of the mine operators themselves. Manufacturers of electric face equip¬ment provided these structures only on the direct order from the mining company and built them to their specifications. In talking to the operators and the miners in mines where cabs or canopies were in use, it was the consensus that these structures did improve safety and that although originally there was some reluctance on the part; of the miners to work in the confines of a cab or canopy, mast would not work without them once they had been adapted to the equipment.

Jan 1, 1975

By John C. Stankus, Xiaoting Li

"Underground structures such as square/arch steel sets, king beam structure, etc. are widely used for the roof support in underground mines. In designing and calculating the required carrying capacities of these underground structures, how to identify the potential rock loads on the structures over long term is a challenging question for ground control engineers. Based on design practices of both surface and underground structures, the authors have designed and applied appropriate load factors in underground structural design projects to accommodate different rock types, entry/intersection dimensions, roof geologic conditions, availability of roof bolts and water, etc. Classification of load (reduction) factors for large-span underground intersections are presented for reference. Success of designed underground structures in effectively controlling roof stability over years indicates the applicability of the load factor concept for underground structural design, and its same significance as of the load factor specifications in ASCE/SEI 7-10, ANSI/AWC NDS (2015), and AASHTO LRFD Bridge Design Specifications (2012). The load factor concept will facilitate ground control engineers to appropriately utilize popular structural design software, such as RISA-3D or -2D to efficiently design and analyze underground structures.LOAD FACTORS IN STRUCTURE DESIGN APPLICATIONSIn structures, loads cause stresses, deformations, and displacements. Assessment of their effects is carried out by the methods of structural analysis with the help of load factors. Loads can be increased or decreased by load factors to meet the requirement that design strength be higher than maximum loads. For example, in designing a staircase, a dead load factor may be 1.2 times the weight of the structure, and a live load factor may be 1.6 times the maximum expected live load based on the Load and Resistance Factor Design (LRFD) method. These two “factored loads” are combined (added) to determine the “required strength” of the staircase. Some typical load (adjustment) factors used for structural design are as follows:"

Jan 1, 2019

By E. R. Palowitch

On February 5, 1973, Eastern Associated Coal Corp began shortwall mining in their Federal No. 1 Mine, thus marking the first attempt in the United States at modern shortwall mining, i.e., using a continuous miner to extract coal open-ended from pillars 100 to 200 feet wide, under the protection of a self¬-advancing roof support system (1)1/. Since then, four additional shortwall faces have been operated. While the number of face-years of shortwall experience in the United States is limited, this experience has been anything but uniform. Differences in operator motivation, coalbed parameters, geologic conditions, panel dimensions, and face equipment all have contributed to a wealth of knowledge which can provide guidance for the design of future shortwalls. The purpose of this paper is to review the history of shortwall mining in the United States and to assess its value to the U.S. coal industry in terms of the health and safety of the miner, the percentage of coal recovered, coal production, worker productivity, and relative cost performance.

Jan 1, 1976

By Thomas E. Ban

During recent years fuel consuming industries of the United States have been caught between environmental restrictions and the uncertainty of obtaining an inexpensive fuel. With the advent of the National Energy Act of 1978 there has been added impetus to switch from gas and oil to coal. For industrial furnaces and boilers that were designed to bum coal, returning to an available compliance coal might be feasible. However, furnaces and boilers designed for gas or oil cannot reasonably be converted to coal unless the coal is initially gasified. All cases, nevertheless, depend upon the availability of an adequate structured coal of a compliance composition, a challenge to the coal mining industry. The foregoing problems have contributed to the current energy-coal crisis of today's economies. It therefore would be worthwhile to capitalize on previous experiences of the mineral processing industry.

Jan 1, 1979

By T. Braun

In 1911, a young mining engineer named Bartlett Thane assembled a large claim block, 4 miles southeast of Juneau, Alaska. Across the Gastineau Channel on Douglas Island, the Alaska Treadwell Gold Mining Company had, by 1904, produced gold valued at more than three times the purchase price of Alaska in 1867 (Kelly, 2010). Thane knew his deposit was lower grade than other mines or prospects in the area; however, if the deposit was developed on a large-scale, the trend and size of the deposit made the project potentially economic. In 1911, Thane developed a business plan for the project and successfully attracted investor interest. In 1912, Daniel C Jackling visited the property at the request of an east coast investment group. Upon inspection of 5 years of production records for the Perseverance Mine, Jackling saw an opportunity to apply the low-grade/high volume milling technology which was widely adopted to the copper porphyry deposits of the southwestern U.S. With a design capacity of 6,000 tons per day (5,454 tonnes/day), Jackling’s innovative mill design would require high volume underground mining methods and the power of two new hydroelectric projects. By 1915, the Alaska Gastineau Mining Company was in full production. Between 1915 and 1919, the mine and mill set production records for haulage and throughput. The hydroelectric projects proved to be successful engineering marvels. Operational difficulties related to ore grade, refractory elements and labor shortages interrupted production on an increasing basis. In 1921, the mining company permanently shut down operations. INTRODUCTION The Juneau Gold Belt begins at Windham Bay near the southern end of Stephens Passage and extends approximately 100 miles north to Berners Bay (Figure 1). The first large-scale and sustained underground mine, operated by the Alaska Treadwell Gold Mining Company in the late 1880’s, established the Juneau-Douglas area as the regional hub for transportation and development. In the mid-1890’s, the combined population of Juneau and Douglas reached approximately 3,000 residents, largely driven by employment and support demands of several small to mid-size underground gold mines in the region. By 1904, the value of the cumulative gold production of the Alaska Treadwell was five times greater than the purchase price of Alaska in 1867 (Kelly, 2010). By the turn of the 20th century, economic growth in the Juneau-Douglas area relied on supplies delivered from the lower 48. Passenger and freight shipping lines required 3 to 4 days to make the one-way trip from Seattle to Juneau. Established shipping routes required experienced crews due to navigation hazards and adverse weather conditions. Even with precautions at the time, steam ships and freighter vessels experienced breakdowns or encounters with natural hazards that resulted in damage or in some cases, sinking. Interestingly, with no roads or railroads connecting Juneau to other communities in southeast Alaska, Juneau still relies on seaborn shipping in the 21st century.

Jan 1, 2019

By John Drew Ridge

Tables showing world trade in metallic mineral raw materials during the years 1953 through 1957 have been prepared for the following twenty-one commodities: alumina, aluminum, bauxite, chromite, copper concentrates, partly refined and fully refined copper metal, iron ore, pig iron, iron and steel (simple shapes), lead concentrates, lead metal, manganese ore, mercury metal, nickel ore, concentrates, and matte, nickel metal, raw pyrites, sintered pyrites, tin concentrates, tin metal, zinc concentrates, and zinc metal. In each instance, the amounts given by the importing country were used except when statistics from the importing nation were lacking, incomplete, or misleading. To show the considerable divergence between importing and exporting country totals for the same years, the complete mercury table is given and, in parallel columns, shows the comparable tonnages of importers and exporters. Tables for the other twenty commodities are presented in summary form. The data of the concentrate tables are used with those of the corresponding metals as a basis for a discussion of trade in concentrates versus trade in metals. The data of all twenty-one tables provide the basis for testing the thirteen rules governing international trade in metal raw materials which I first published in Mining Engineering for July 1955. Because the 1953 through 1957 data are far more complete and considerably more extensive than those on which the 1955 rules were based, it was found possible to deduce five additional rules and to modify three of the original thirteen appreciably. The full text of the eighteen rules is given.

Jan 1, 1960

By G. A. Johnson

Basic management principles will be discussed (as they apply to minerals education efforts), especially in light of the changing nature of volunteerism in today’s society. Also, the “minerals education tree” will be presented, along with public opinion / public policy realities.

Jan 1, 2001

By M. SIDDARAJU, Rameshwar Sah, T. Umadevi, K. S. SRIDHARA, B. D. Ganesh Shetty, M. RAJU

The production of high strength iron ore sinter for blast furnace iron making unit was developed by optimizing the granulometry of less than − 0.150 mm fines in sinter base mix which consists of iron ore fines (− 10 mm size with 0.150 mm: 41%), beneficiation plant jig concentrate, i.e., washed ore (− 3 + 0.150 mm size with − 0.150 mm 3 to 9%), beneficiation plant concentrate (− 0.150 mm size 97%), limestone, dolomite, coke breeze, lime, sinter return fines, direct reduced iron (DRI plant) fines, and micropellets produced from steel plant waste. The sintering process consists of preparation of base mix, mixing, and production of nodules using mixing and nodulizing drum by maintaining the optimum moisture, transferring of nodules to the sintering machine, and firing of sinter by applying optimum suction pressure. To optimize the < 0.150 mm fines in sinter base mix, the − 10-mm size iron ore fines was replaced with washed ore. The size analysis, granulation index (G index), and optimization of moisture w.r.t. sinter bed permeability were carried out by varying the washed ore addition from 0 to 55% in sinter base mix to vary the − 0.150 mm fine size. With decrease in washed ore addition from 55 to 0% in sinter base mix the finer fraction, i.e., − 0.150 mm in sinter base mix increased from 9.4 to 26.7%. Granulation (G) index increased from 1.46 to 3.10, sinter bed permeability increased from 33 to 53 Japanese Permeability Unit (JPU), and balling index increased from 1.4 to 3.0. With increase in − 0.150 mm fines in the sinter base mix from 9.4 to 26.7%, the sinter tumbler index (T.I) increased and sinter reduction degradation index (RDI) decreased. Increase in sinter strength and decrease in sinter RDI was due to increase in formation of Silico ferrite of calcium and aluminium (SFCA) phase and decrease in pore phase. The SFCA is the main bonding phase in iron ore sinter, and it provides strength to sinter. Sinter base mix with − 0.150 mm fines 18.9% (washed ore addition 25%) achieved desired sinter properties with moisture 8.0%, G index 2.44, balling index 2.3, and sinter bed permeability > 45JPU. Decreased the sinter properties with washed ore addition in sinter base mix beyond 25% due to decrease in − 0.150 mm fines in sinter base mix. Further, to improve the sinter properties with washed ore 30 to 45%, 3 to 10% beneficiation plant concentrate, i.e., − 0.150 mm fines was added to maintain the 18.9% of − 0.150 mm fines in sinter base mix. From the laboratory sintering studies, it was found that minimum 18.9% (range from 18.9 to 26.7%) − 0.150 mm fines should be maintained in the sinter base mix to achieve desired sinter properties.

Oct 16, 2021

By R. J. Zagrocki

Rekindled public concern about lead toxicity has intensified the awareness of lead-bearing materials in contact with the environment and the human population. Lead&apos;s common association with other metals makes the increasingly restrictive lead standards a primary concern for a large number of metal and metal-related industries. In commercial scale demonstration tests with lead-bearing wastes, the HRD Flame Reactor process has a demonstrated ability to separate and recover over 95% of the lead as a recyclable oxide, while rendering the remainder of the material as vitrified, non-leaching, and nonhazardous co-product. Recent Flame Reactor process tests and preliminary cost data for secondary lead soda slag are highlighted.

Jan 1, 1992

By G. R. Erdman

The industrial mineral filler plant of the Gouverneur Tale Company is equipped with a good dust collection system installed long before the recent popularization of environmental pollution. Credit for this fact is due to the foresight of Mr. R. S. McClellan, Project Manager and subsequent Vice President and General Manager of Gouverneur Talc, who recently retired as Vice President Engineering of the parent organization, the R. T. Vanderbilt Company. Also instrumental in the early stages of plant operation and the solution of start-up problems was J. A. Gustin who is now an engineering consultant located in Martinsville, Va. Credit is most certainly due to the late R. T. Vanderbilt, the company&apos;s founder, who favored and approved the investment in the necessary facilities that were far ahead of all competitors in the industry at that time.

Jan 1, 1972

When science and the human spirit come together amazing things can happen. This was perhaps never more evident than through the events that unfolded during August and October in a remote desert in northern Chile. On Aug. 5, the main shaft of the San José copper and gold mine near Copiapó in Chile?s Atacama Region collapsed, leaving 33 miners trapped more than 624 m (2,000 ft) beneath the earth?s surface.

Jan 1, 2010