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By Mortimer J. Richardson, Earl H. Malmstrom

INTRODUCTION The art of placer gold mine evaluation and mining has had an interesting evolution beginning in earliest times. DE RE METALLICA (c.1556), documents the use of rockers, circular sieves(jigs) and riff lest for classifying, concentrating and recovering placer gold, respectively. During the late 1800's in the heat of the international gold rush, a bucket ladder mining dredge containing its own processing plant was developed that enabled digging of placers to bedrock that were inaccessible to the hand miner. The power driven churn drill was developed at about the same tie that facilitated more rapid and larger scale sampling of placers to bedrock. The mineral jig was applied in the early part of the 1900,s to begin the replacement of riffles on placer dredges. Mining dredges proliferated in California and New Zealand to mine the deeper placers and spread throughout the world. The companies that were leaders in dredge mining technology conducted experimental work that advanced the state of the art by processing of gravels with jigs and amalgam systems to recover gold on board dredges in a continuous process. This paper will synthesize the technology of placer gold exploration, mine development and operation into guidelines for evaluation and development of small-scale prospects. Prospect Reconnaissance The location of a prospect usual1 y results from some physical evidence of the presence of gold and/or past mining activity. Any earlier activity that may have produced gold from the prospect, should be investigated before making the trip. The initial reconnaissance should attempt to verify a near-surface presence and then make observations concerning the geomorphic characteristics that relate to placer gold accumulation. Estimates of the probable depth, breadth and length of mineable gravels can be made from the surf ace by the experienced placer mining engineer. With this information, he can speculate on whether there is a viable prospect to be pursued. The placer mining engineer should be experienced in panning samples found in shallow diggings or from existing pits. This will give him immediate indications of gold presence without fear of "salting" by an over-ambitious promoter of the project. The same capability of panning is important during the other sampling phases. A thorough knowledge of logging and calculating the results is essential to proper evaluation of the deposit' s tenor. Evaluation Methods Depending upon the character of the prospect such as river, benches, terraces, jungle, the type of equipment to conduct sampling of the deposit must be determined. In most cases, the drill has replaced bulk sampling. The churn drill has had the greatest amount of accumulated experience but is slow. The reverse circulation drill (RC), is limited by its lack of verification in subsequent mining in order to prove its reliability. However, in the hands of knowledgeable placer mining engineers experienced with its use and calibration, it may be used. The RC Hammer drill (such as the Becker), can be as much as ten times faster than the churn drill and compress the time necessary to prove a prospect, or, to disprove it. All costs in balance, it is often cost effective over the churn drill.

Jan 1, 1987

By D. A. Ellis

This paper review s several new applications of solvent extraction developed in conjunction with a research project carried out under the AEC Raw Materials Division by the Dow Western Division laboratories during the last two years. A process for recovery of uranium from ores by contacting the solid directly with organic solvent without a prior aqueous leach and a process for uranium recovery by contacting thick, unfiltered leach slurry with the solvent were studied in an attempt to simplify ad reduce the cost of ore treatment procedures. Processes to produce pure UF4 products at the concentrate mills thus eliminating the production and subsequent dissolution of the concentrate were investigated. Since many of the leach liquors contained vanadium as well as uranium, solvent extraction processes for by-product vanadium were also studied.

Jan 1, 1958

By H. S. Castro

The by-product molybdenite technology in Chile is reviewed. Flowsheets, reagents and some operation features for the actual six Chilean moly plants(Chuquicamata, El Teniente, El Salvador, Andina, Las Tortolas and Pelambres), are presented. The chemical and physicochemical factors involved in the depression of copper and iron sulfides during the selective flotation of molybdenite, with sodium sulfide, sodium sulfhydrate, anamol-D and LR-744, are discussed. Advances in technology to solve problems of excess of lime (precipitation with sulfuric acid); excess of residual flotation reagents (activated carbon and kerosene); and optimization of depressant consumption (Eh control, nitrogen and low-oxygen air), are discussed.

Jan 1, 1998

By P. Riveros, J. Binvignat, V. M. McNamara, D. Koren

The feasibility of recovering cyanide and copper from a gold mill barren solution was evaluated in a small A VR pilot plant. The campaign lasted 64 hours, during which time about 4,000 L of gold mill barren solution were processed. The results showed that A VR is an effective technology for recovering cyanide and copper from barren solutions. Under the best conditions, the copper precipitation and the cyanide volatilization attained 94% and 98%, respectively. Using 5 MNaOH as the absorbent, practically all the HCN gas was recovered in the form of a concentrated NaCN solution containing 70 g/L free CN. Basic engineering design parameters applicable to a large-scale operation were obtained, including the Henry's Law constant and the mass transfer coefficient for HCN gas.

Jan 1, 1997

By Sergio Flores, Nate Long, William Hodder, Phil Rhodes, Tim McQueary

The Surface Water Supply Project Segment B3 is a 4 miles section of tunnel that will run East- West in Houston TX, from Hopper St to I-45. The tunnel will be mined by using a 128" Dia refurbished 1987 Lovat Tunnel Boring Machine capable of operating in Open or EPB mode. The tunnel will be temporarily supported with ribs and lagging and a 96" Dia pipe will be grouted into place. All four miles of this project are within Petroleum Pipeline Easements. The project includes seven shafts, 2000' of tunnel in potentially petroleum contaminated ground, crossing the Hardy Toll d, I-45, the nion Pacic ailroad ight of Way and multiple oil and gas pipeline crossings. This paper summarizes the planning and drive performed to date.

Jun 23, 2024

By Daniel Su

This paper describes recent ground control challenges encountered at the longwall recovery areas of one of Bailey Mine?s two longwall faces and the proactive measures taken by CONSOL management and engineering to mitigate them. The challenges derived primarily from the following causes: (1) irregular roof coal and draw slate thickness, (2) presence of thick sandstone at the recovery area and extremely weak rocks below the sandstone, (3) close proximity to a regional anticline, (4) low shield set pressure and tip load, and (5) ineffective primary roof support that led to progressive failure of the headgate roof. The presence of the anticline contributed to extensive fracturing of the sandstone. Excessive pot-out in advance of the shields frequently occurred near mid-face due to the presence of thick draw slate and irregular roof coal near the recovery area. This, in turn, resulted in face heights that exceeded the maximum reach of the shields. Subsequently, during longwall meshing, when the advance rate slowed considerably, fractured sandstone would often break loose, causing the shields to yield, thereby reducing the height and inhibiting shearer movement. To improve the headgate and face conditions within the longwall recovery area, several actions were taken, including: (1) assessing site-specific roof geology by conducting in-mine roof coring around the recovery areas and by mapping immediate draw slate and roof coal thicknesses within surrounding entries, (2) increasing pump pressure and thus shield set pressures (3) diligently monitoring shield set pressures and longwall extraction horizon, (4) installing additional cable bolts and roof screening to prevent progressive failure of the immediate headgate roof, (5) fully-grouting supplemental cable bolts to improve headgate support stiffness, and (6) gluing the headgate roof within the recovery areas with polyurethane. As a result of these collective efforts, longwall recovery delays at Bailey Mine were reduced from 21 days in 2006 to nearly zero in 2009.

Jan 1, 2009

By G. W. Kenzy

Recently, in the United States, questions of possible deleterious synergistic health effects of the gaseous and particulate components in the diesel exhaust and mineral and coal dust have been the impetus for extensive research by several agencies. At the present time, diesel engines are tested and approved for use in gassy and non-gassy underground metal and non-metal mines under Parts 31, 32, and 36 of Title30 of the Code of Federal Regulations. Diesel-powered equipment for use in underground coal mines, though not explicitly addressed in the law, is administered under Parts 32 and 36 of Title 30, with Part 36 being applied in the case of equipment working inby the last open crosscut or in the return airways. Operation of diesel equipment in underground mines has the potential for serious health and safety hazards from the gases, vapors, and particulates in the exhaust. Therefore, various countries have rules and regulations for the safe deployment of diesel equipment. The applicable laws and regulations from several countries who have long experience with diesel-powered equipment in their mines are reviewed. Four major areas have been addressed: (1) testing and approval procedures of diesel engines, (2) ambient mine air quality specifications, (3) frequency of sampling and location of samples, and (4) air quality specifications in splits where diesel-powered equipment are operated. The review indicates that most regulations generally consider four possible hazards: (1) toxic components in the engine exhaust, (2) ignition of flammable atmospheres by the engine or electrical equipment, (3) fire hazards presented by the engine fuel oil and by combustible material that might come in contact with the equipment, and (4) mechanical hazards. There is a remarkable similarity in the laws with regard to engine design, testing and approval procedures. However, the aspects with regard to mine air quality and quantity are quite variable-- from a general statement to very specific standards for many different diesel exhaust constituents. However, the laws with regard to synergistic effects of diesel exhaust components and other mine air contaminants are an exception.

Jan 1, 1980

By M. Guzman, S. B. Thais, M. F. Obispo, M. R. Arribasplata

The impact generated by old abandoned mines in Peru have produced mining environmental liabilities, which can generate an impact on the environment. In the search for long-term sustainable solutions, Phytoremediation is presented as an interesting alternative, since it allows the use of Peruvian native plant species for the accumulation of heavy metals. In this paper, we present the results of native high Andean species: Stipa Ichu and Cortaderia Nitida. The final metal concentration in the aerial parts and in the roots of each plant show that Stipa Ichu is more efficient to recover Fe, reaching almost 278 times its initial value. In the same way, this plant is efficient to remove Zn, Cu and Cd, reaching maximum values of 64, 39 and 12 times its initial concentration respectively. Cortaderia Nitida turned out to be more efficient to recover Fe, Zn, Cu and Cr, with highest recovery of 250, 117, 39 and 13 times its initial value respectively. Finally, based on translocation factor, Stipa Ichu has better capacities of hyperaccumulation of Fe, Cu, Zn, Pb and Cr. Cortaderia Nitida only shows hyperaccumulation of Cr.

Mar 2, 2022

By Robert M. Dreyer

Thirty years ago it was possible to locate a quarry site for crushed rock for concrete aggregate by finding the nearest solid rock bluff accessible by road, But times have changed and the location of a quarry site to furnish crushed rock for concrete aggregate now has become rather complicated, Although both sand and gravel can be used for aggregate, this discussion will be confined to crushed rock in the regions around a metropolitan area. Let us assume that a consultant has been retained to advise on the desirability, and the possibility, of opening a new quarry within a given area. The problems are geological and ecological. Since the geological problems are simpler, they will be discussed first. Generally, the first step is to make a market study of competitive aggregate sources within the projected area. Assuming that the quality of aggregate to be sold by competitors as well as their mining costs will, within narrow limits, be the same, the problem becomes essentially a study of haulage costs from established quarries into the projected new area. Since haulage cannot be effected along straight lines and since each quarry operator may have different unit haulage costs, a map showing lines of increasing cost intersecting points on roads available for truck haulage radiating from competitive quarries can be rather complicated. Such a map, more-over, changes each time a new haulage contract is negotiated by a

Jan 1, 1971

By K Louie

When BHP Copper's Lower Kalamazoo Project commenced production in January 1997, two of the four original hoists had been converted to hoist ore from the Lower K level. Conversions on these hoists not only allowed hoisting from a much deeper level, but also created a higher hoisting efficiency and higher capacity as well. Conversions included new drums, new cables, SCR drives and other solid state control technologies not available when the original hoists were installed. Two of the original hoists were installed in the 1950's and the other two were installed in the 1970's.

Jan 1, 1998

By William J. Taylor

Strictly defined, a stull is an inclined or horizontal timber support; a vertically placed timber is defined as a prop. Common usage allows the catchall term "stull" to refer to all such uniaxial mine support, regardless of orientation. Typically a stull is a round wooden column that is wedged in place to provide short-term auxiliary support between sill and back, or between hanging wall and footwall. Stulls may be used exclusively or in con- junction with other support systems such as roof bolts, shotcrete, or cribbing. Stulls are used both as local temporary support in stoping operations and for uniform systematic support installations. Where stoping areas are to be abandoned soon after excavation, stulls may be used to provide temporary support during mining operations. Where controlled caving and subsidence is required, stull supports are designed to fail in a systematic, predictable manner. Wood type is selected on the basis of availability, price, and load carrying characteristics. Coniferous woods are typically used, especially to carry heavy ground loads. Brittle woods are generally avoided because of their tendency to fail suddenly. Gradual yielding failure is preferable to sudden, unexpected failure of the support. Some usage of wood from deciduous trees such as cottonwood and other poplars has been reported in Grants, NM. These stulls reportedly mushroomed as the ground load increased but continued to maintain their structural integrity. Stulls fabricated from structural steel are used in special applications. Adjustable lengths are commercially available in mechanical, hydraulic, and pneumatic designs. The high cost of mechanical stulls limits their use to mining systems where recovery and reuse is possible. End blocking, also called headboards or footboards, uses wood blocks that are placed between the stull end and the ground they are supporting. The blocks are typically 50.8 to 101.6 mm (2 to 4 in.) thick, 203.2 to 304.8 mm (8 to 12 in.) wide, and 381 to 609.6 mm (15 to 24 in.) long. End blocking serves to distribute the support over wider back area. Compression of the end blocking gives visual indication of wall movement prior to failure of the stull. A common application of the stull is in flat-bedded uranium mining during pillar extraction. Many western US uranium mines use a pillar pattern development to delineate the irregular ore pods. After development of an appropriate sized pillar, the ore pillars are then sequentially mined out, leaving the undercut hanging wall or back to cave. Where thickness of the ore is less than 4.3 m (14 ft), stulls are generally used to provide ground control as the pillar is removed in slices. Experience dictates the density of stull placement. In general, the number and size of stulls should be sufficient to resist ground closure and to provide support for drilling and loading operations adjacent to the pillar. Stulls next to the mining face are often lagged 0.9 to 1.2 m (3 or 4 ft) up from the floor (or sill) to confine the blasted ore to a passage next to the pillar. Mucking is simplified by this confinement. Experience dictates whether back control along a mining face requires removal of stulls to allow con- trolled subsidence of the back or hanging wall. Without caving or closure, abutment pressure can create poor ground conditions near the pillar.

Jan 1, 1982

By Sotiris Psomas, Colin M. Eddie

"Steel Fibre Reinforced Concrete (SFRC) Segmental Tunnel Linings have successfully been used for over 20 years in the UK and have been adopted in a number of high profile projects such as High Speed 1, Crossrail, Thames Tideway, as well as High Speed 2. Tunnel linings and especially SFRC design are not covered in the Eurocodes. This shortage of SFRC tunnel design rules seems to be partially addressed by several international publications. However, in the UK, the ‘design-assisted by testing’ (DAT) approach has also been adopted. The Paper discusses the UK’s best design practice and focuses on the DAT methodology as applied in the case of the 6.9km (4.3miles), 7.8m (25.6 feet) ID Lining for the £635million Lee Tunnel Project. The design approach, the full scale testing at the Building Research Establishment (BRE), and the construction innovations are presented. This experience will be transferred to the £4billion Thames Tideway Tunnel.INTRODUCTIONSteel Fibre Reinforced Concrete (SFRC) has been used for Tunnel segments for more than 20 years. The first application of SFRC in the UK was for the Heathrow Baggage tunnel (1994). Since then significant size tunnels have been designed and constructed, such as the Jubilee Line (1999) High Speed 1 (CTRL, 2006), Crossrail (2014), Lee Tunnel (2014) and the scheduled 25km Thames Tideway (‘Super Sewer’) and High Speed 2 rail tunnels. However one the main obstacles in achieving streamlined design and improving efficiency are the lack of appropriate design guidelines for SFRC tunnel segments. This issue will – to some extent – be addressed by a number of current documents on tunnel FRC design either being produced by BSi (PAS8810, expected 2016), ACI (544.R) and ITAtech (Design Guideline PCFRC, 2015) in an effort to advance the design of SFRC and take into consideration the recent developments in Steel and Macro-Synthetic FRC technology."

Jan 1, 2016

Though the mining industry is beset with problems-a broad slump in metal prices, a rash of acquisitions and takeover attempts, rising capital costs, and an aggressive Canadian energy program-there was an under-current of optimism at the 1981 AMC conference that's been missing at industry meetings in recent years. The industry anticipates a turnaround in the 1980s, buoyed perhaps by the new spirit of cooperation from the Reagan administration. For the first time in years, it appears that Washington and the mining industry share mutual goals for developing the nation's resources. A number of prominent Reagan officials were on hand during the three-day conference in Denver, September 28-30, to reassure conferees that restrictions plaguing energy and minerals development would be eased. Interior Secretary James Watt and other government speakers promised cooperation in bringing balance to federal public lands policies, a review of regulations that have hampered the industry, and prompt action on domestic minerals policy. Daniel N. Miller, Jr., assistant interior secretary for energy and minerals, said, "It is our intent to dismantle the overhearing bureaucracy that has stifled mineral and energy exploration. We know that Interior's rules have shackled the mining industry in recent years, and we know that those rules must be eased." Miller noted that the administration will not permit mining on national park lands or wildlife refuges, but added that "we must assess a variety of uses of public lands ... we will restore lands to multiple use where practical." EPA administrator Anne Gorsuch assured industry representatives that the administration intends to work within environmental laws and with Congress to review and revise water, soil, and air pollution policies. "We have a strong commitment to see that there are major mid-course corrections" of air regulations, Gorsuch said. Support from these "new friends in Washington" will be crucial in light of the serious problems pressuring the industry. Copper prices have plunged to almost three-year lows and prices for molybdenum, gold, and silver have slumped. Earnings are down and today's high interest rates prevent a quick turnaround. Companies are on edge after the recent takeovers of Kennecott, St. Joe Minerals, and Texasgulf Though the companies may benefit from the major injection of capital that large energy firms can provide, many observers fear the new parent companies won't be willing or able to survive the cyclical metal markets. Arco and Gulf Resources, for example, have been criticized for closing Anaconda's Montana copper facility and the Bunker Hill unit in Idaho, respectively. Canada's national energy program has brought additional pressure on the industry. This policy, which emphasizes Canadian majority ownership of the country's energy sources, resulted in acquisition of Texasgulf's Kidd Creek lead-zinc-silver complex by Canadian and French interests. In response, the American Mining Congress adopted two resolutions on takeovers. One calls for the US government to review laws regulating tender offers and takeovers "to better ensure that principles of fairness and sound investment policy govern such transactions.'' The other asks the government to demand "fairness and reciprocity" as a basis for US policy governing international trade in minerals and investment relations with other countries. AMC's shopping list included four other priority goals, aimed primarily at the Interior Department: • Prompt implementation of Interior's efforts to bring order and balance to rules governing access to public lands for exploration and development. • Statement by the President of a comprehensive and coherent domestic minerals policy. • Amendment of the Clean Air Act to remove impediments to productivity and barriers to economic development that are not necessary to essential goals of the act. • Development of new approaches to better achieve worker health and safety in the most cost-effective manner without penalizing productivity. Almost 6000 mining industry executives attended the 1981 convention-the largest in AMC's 84-year history. As in years past, the conference offered a wide spectrum of presentations-nearly 100 papers in 26 sessions-ranging from commodity forecasts to the latest technical achievements. New Administration Stockpile Goals The minerals availability session included a presentation on management of the minerals stockpile by Paul K. Kruege r of the Federal Emergency Management Agency. Krueger notes that rather than providing incentives for development of a domestic raw materials industry, the government has "a history of providing disincentives to industry." In mining industries, he adds, the rate of productivity growth has been -6% over the last six or seven years. Krueger feels there will be a major change under the Reagan administration. In March 1981, FEMA began the first purchase program for the national defense stockpile in over 20 years. The stockpile is sadly out of balance, Krueger adds. Stockpile materials are

Jan 12, 1981

By Stephen W. Lambert

One of the primary interests of the United States Department of Energy's Mine Planning Division is to fully develop avenues of technical research which potentially offer positive effects on coal mine productivity. One such area of research involves the removal of methane gas from unmined portions of coalbeds through vertical wells drilled from surface locations. As coalbed methane content is reduced, less gas is available for flow into the mine, and consequently ventilation requirements are decreased and/or coal extraction rates increase. Another attractive aspect of the vertical borehole drainage method is that it presents an opportunity to recover and utilize significant quantities of methane gas, which would otherwise be wasted to the atmosphere. The viability of removing gas from the Mary Lee coalbed using stimulated vertical boreholes was first suggested by Elder and Deul as a result of a United States Bureau of Mines' drilling project conducted from 1971 to 1974 (4). Other United States Bureau of Mines' studies forecasted that degasification would eventually be necessary in the Mary Lee coalbed because most new or expanding mine development would take place at depths exceeding 1 000 feet (305 meters), where the methane problem would be severe (3) (13). In 1975 a large-scaled drilling program was designed in order to supply industry's anticipated need for a degasification technology in the Warrior coal basin, Alabama. The results of this government/industry sponsored effort were to be specifically applicable to the Mary Lee coalbed, the most extensive and economically important deep minable coal present in the area. Major technical objectives of this program are twofold: (1) to measure the effects of various well completion designs, particularly hydraulic stimulation, on mining and (2) to determine the effects of well spacing on gas drainage rates. A cooperative agreement was established with United States Steel Corporation in late 1975 and field work began shortly thereafter in the proximity of a newly developing mine near Oak Grove, Alabama. Government responsibility for this program was transferred from the United States Bureau of Mines to the United States Department of Energy in October 1977. To date, as a result of this program, twenty-one wells have been completed into the Mary Lee coalbed at the Oak Grove site. Seventeen of these wells were drilled on an experimental grid pattern located two miles from the active mine. These grid wells are primarily being used to generate data necessary to determine the effects of well spacing on gas drainage rates and will also provide a large amount of information regarding the long-term effects of degasification on mining. The four remaining wells (designated Ton through TW4) were placed near the mine so that the full effects of completion could be studied within the short time required for underground interception. Results gathered from the first two test wells (TW1 and TW2) have been reported in detail (10) and indicated that several improvements were necessary to increase gas drainage rates. Hydraulic stimulation was one of the most important aspects of well design that required improvement. Nitrogen-charged foam stimulation treatment was used at TW3 and TW4 instead of the gelled-fluid type stimulation used at the first two near-mine test wells.

Jan 1, 1980

By Rainer Antretter

"THE CHALLENGE The 14km long, Arlbergtunnel, closed for public traffic during summer 2015, receiving a comprehensive and substantial renovation from 2015 to 2017. The main works discussed here, carried out during 2015, comprise 37 drill and blast SEM/NATM emergency escape tunnels from road level to the ventilation duct plenum have to be constructed as well as eight additional lay-by niches and three transformer tunnels. This presentation comprises the construction ventilation design, designed according to national regulations, suitable for 150 employees working 24/7 simultaneously at more than 40 single working sites lined up along the tunnel. The ventilation-system chosen was utilising two existing shafts for intake/discharge and a cross passage to surface, to handle a total fan power of 1.600kW. DESCRIPTION OF RENOVATION WORKS Linking Tyrol and Vorarlberg, two Federal States of Austria, the Arlbergtunnel is a single tube two-way road tunnel with vent duct plenum, constructed in the mid-1970s. According to latest EU legislation, additional escape exits have become obligatory. The existing seven cross passage links to the adjacent Arlberg Railway Tunnel, with average spacing of about 1.500m constructed in 2007, an additional upgrade to shorter escape spaces of approx. 400m was now required to comply with the updated legislation. Additional transformer tunnels, lay-by niches and small niches for emergency maintenance use, cleaning and other purposes, as well as a the installation of a new fire main in the invert, coupled with the simultaneous replacement of virtually the entire power and signaling cables, generated several dozen small and large single sites distributed along the 14km of tunnel.Purpose of the 37 walkable emergency escape tunnels is to reach the “upper deck” of the Arlbergtunnel, the vent duct plenum. These have an 180deg curve in plan, inclined at 10% and approx. 60m (65yd) long tunnels, excavated using drill and blast method starting from road level and working upwards to the level of an “intermediate soffit”, the vent duct plenum in the crown of the tunnel. The vent duct plenum is separated into a fresh air part and an exhaust air part, shown in Figure 1. The escape tunnels end with a pressure door in the fresh air section of the ventilation duct plenum. From there illuminated signs show the shortest escape route to the safe area between the road tunnel and the railway tunnel, as shown in Figure 2."

Jan 1, 2016

By Donald Crowell

Due to falling metal prices and depletion of ore reserves, lead-zinc mining in the Leadville, Colorado, area gradually came to a halt in the 1950's. Exploration work continued, however, and by 1969 sufficient ore had been blocked out to warrant sinking a shaft and erecting a new concentrator to treat 700 tpd. The new shaft and concentrator were to be located in Iowa Gulch several miles east of Leadville at an elevation of 11,100 ft. The Leadville project is a joint venture between Newmont Mining Company and ASARCO with ASARCO being the operator. Design work began in the fall of 1969. Engineering was done by Torkelson Engineering Company of Salt Lake City in conjunction with the Central Engineering Department of ASARCO. The plant was constructed by Stearns-Roger Corporation. Construction began in the spring of 1970 and the plant went onstream in April, 1971. Flow sheets and equipment lists are attached. This paper will describe the flow sheet very briefly and discuss in more detail those aspects of the design which may be of interest, particularly the provisions for expanding the capacity of the plant.

Jan 1, 1972

By P. Zhang

A 1989 FIPR characterization study of the future phosphate resources in Florida showed that MgO would be a problem with both the pebble and concentrate as phosphate mining moves deeper. Since the ratio of concentrate to pebble will become higher and higher in the future, reducing Mg content in the concentrate by a small margin would allow blending of a large portion of the high-dolomite pebble. This research was conducted based on that logic. The following six approaches were tested for reducing MgO content in the flotation concentrate: (1) Adding a dolomite depressant in the rougher flotation step; (2) Dolomite flotation on the rougher concentrate with and without grinding; (3) Dolomite flotation on the cleaner concentrate with and without grinding; (4) Scrubbing the flotation feed; (5) Scrubbing the rougher concentrate; (6) Scrubbing the cleaner concentrate. Successful methods include adding a dolomite depressant in the rougher flotation, dolomite flotation on the cleaner concentrate with grinding, and scrubbing the cleaner concentrate in quartz sand. These techniques could reduce MgO content in the final concentrate by 20-40%. The flotation process could achieve a concentrate with the lowest MgO content, but it is the most expensive approach. Adding a dolomite is inexpensive and easy, but the effect is limited. Overall, scrubbing may be the most promising technology for this purpose.

Feb 23, 2014

By Christopher Newman, Andrew Minckley

With underground stone operations developing in deeper and more geologically complex conditions, accurate pillar stability analysis becomes for the evaluation of engineering design. This paper provides engineering-based recommendations for applying LaModel to evaluate multiple-level room-and-pillar stone mines in both shallow and deep cover. It provides practical guidance on model calibration using field observations, selection of input parameters, and interpretation of results to inform design and operational decisions. The analysis demonstrates LaModel’s effectiveness in simulating pillar load transfer, stress redistribution, and failure mechanisms in complex mining geometries where empirical methods may be inadequate.

Feb 22, 2026

By W. F. Riggs

INTRODUCTION Flotation equipment is becoming more definitive in design as well as greater in dimension. The last ten years have witnessed the implementation of large flotation cells ranging in size from 28 to 85 cubic meters. However, small plants still operate with cells as small as 3 cubic meters. These changes have increased the operational sensitivity of the flotation system to the chemical reagents used. No scientific study has been undertaken to develop the relationship between the size of equipment and the response of reagents in the flotation system. Hence, this article is an attempt to present several observations from past experience for the purpose of stimulating future research in an area previously ignored and perhaps subsequently not used to advantage. CONVENTIONAL FLOTATION Recent advances in conventional flotation cell design have been made in two areas: a. Flotation cells are becoming larger, and b. Basic design of flotation cells has changed. They can be classified into two types: deep cell and shallow draft cell. Size and design changes of flotation cells have a greater effect on frother performance than on the performance of other chemical reagents. Hence, the discussion in the following sections is restricted to the impact of frothers in the flotation system. Flotation Cell Size The advent of increasing flotation cell size has resulted in the increase of frother consumption. There appears to be a correlation between reduced horsepower (kilowatt) consumption and increased frother consumption per ton of ore processed in the circuit. This is more prevalent when the frother chemistry remains unchanged. Another reason for increased frother consumption is the increased distance between the rotating central shaft and the lip of the cell for larger flotation machines. Increasing this distance results in increased surface area corresponding to the larger cell size. Reduced power input per ton combined with the need for longer, stronger load support of the froth bubble as a result of increasing cell size has resulted in the development of a new series of stronger and more persistent frothers. By the same token, these newer, stronger frothers are difficult to control when applied to the smaller cells. This is true even at lower dosages because the break point between too much frother and not enough frother for optimum metallurgy is normally very narrow. This problem is often exaggerated when operators have established an optimum setting for pulp level and air for the particular frother in use. Generally, the tendency is to operate the flotation cells simply by adjusting frother dosage. The increase in frother strength to accommodate the large cells often results in the realization, after a retrofit, that the existing pump box or sump which is still handling the same volume of concentrate is no longer adequate in size. Flotation Cell Design The two most common flotation cell designs installed during the past ten years are the deep cell and the shallow draft cell. The deep cell provides for complete mixing of air and pulp at the bottom of the cell. The shallow draft cell does all the mixing/pumping in the bottom haft of the cell whereas the mixing of the air is performed further up the shaft and is brought into contact with the pulp midway up the vortex. There are many preferences for one or the other. It is the author's contention that both designs have very valid concepts and must simply be suited to the particular situation as required by the operator. The following comments are subjective observations which should be explored in greater detail. The deep cell mixes both air and pulp together at the bottom of the cell requiring a full depth ascending of the homogenized air to the surface to form the froth layer. This design, in combination with charged air, provides for good concentrate grade control under adverse conditions of selectivity, especially when faced with a fine grind and a slime-laden gangue. A selective frother can be applied without a competitive loss in recovery. One of the conditions for good selectivity in this environment is operating at medium pulp solids concentration in the range of twenty-six to thirty-four per cent (26-34%). When a higher solids concentration is used in combination with a coarse grind, it becomes difficult to maintain the same recovery with a selective frother due to higher pulp viscosity. This condition sometimes results in an unacceptable coalescence of the air bubbles as they ascend the full height of the deep cell. The increased pulp viscosity at higher solids concentration can also retard the flotation kinetics. The combination of decreased surface area of dispersed air and slower kinetics can result in reduced recovery causing coarse particles to continue to drop

Jan 1, 1989

By Ray Nivens, Umit Turunc, Caroline Sui, Nick Morrison, Douglas Steiner

"In most copper mines and concentrators, mill water is continuously recovered and reused, with fresh water added to make up for losses. When mixed, these water chemistries can lead to severe scaling, especially in pipes, tanks and pumps on the mill water supply side, reducing flows and causing significant production losses.At KGHM Robinson Nevada Mining Company, increases in the fresh water addition ratios resulted in severe scaling problems and premature pump failures thereby jeopardizing plant production. What initially appeared to be a few isolated scaling events eventually unfolded into a recurring pattern of water supply-related production losses with increasing severity. Through completion of detailed root cause analysis, chemistry modeling, laboratory work, in-plant testing and system engineering, the mechanisms of scaling were identified and addressed.Advancements in fresh water addition practices and antiscalant application methods resulted in a stepwise reduction of the mill water scaling. Cost savings and production benefits were significant to the plant’s financial metrics.IntroductionThe production of mineral and metal concentrates using the flotation process requires large quantities of water. Flotation is utilized as the primary means for beneficiation with sulfide ores. Mined ores are crushed and ground into a slurry of 20-55% solids. For each ton of ore, 400-900 gallons of water1 are needed to supply the grinding mill. Additional water is needed in the flotation circuit as well. With many modern mills operating at2 11,000-165,000 tons/day, water supply volumes can be upwards of 3,000 gpm to 100,000 gpm of flow.For plants operating at or above capacity, disruptions and restrictions in water supply flow can have a direct impact on the production and recovery of the metal. Water supply flow can be limited for a wide variety of reasons but of interest are those limitations that are due to mineral scaling. Mineral scaling is the selective point precipitation of inorganic species above saturation concentrations. Precipitated species form flow-restricting deposits in the mill water system (tanks, pumps, pipe and valves), that will eventually impact water supply to the concentrator."

Jan 1, 2017