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By Graham Davis

The future of the world's minerals industries is often painted as bleak. Peter Drucker has repeatedly proposed that the demand for minerals has become "uncoupled" from world economic growth.' This implies that, while mineral demand was in the past linked to the growing demand for and consumption of goods and services, further world development will not require substantial mineral inputs. Lester Thurow noted that for these reasons the US minerals industry is diminishing in scale and economic importance.2 There is some documented evidence of such uncoupling, and the demand for minerals may indeed diminish in the future. But such announcements are, to this point, no more than speculation. For instance, is it not just as likely that renewed environmental concerns will cause increased demand for the relatively innocuous environmental properties of metals, replacing plastics? And even if the prophesied demand decreases do occur, a sufficient fall in metal prices due to technological advances could increase the quantity of minerals demanded above current levels, in spite of leftward shifting demand curves. Thus, worldwide mineral production activity may increase or decrease in the future and no one can say whether more or fewer of the earth's citizens will become involved in the extraction and processing of minerals.

Jan 1, 1994

By Dennis S. Kostick

Introduction Soda ash is known chemically as sodium carbonate, an important inorganic chemical. It has been produced for several centuries by processing certain vegetation and minerals. The US soda ash industry has evolved from several small sodium carbonate mining operations in the West. Now, a nucleus of six companies produce about one-fourth of the world's annual soda ash output US producers currently dominate the world market. But certain international events are occurring that will reshape the domestic soda ash industry in the next decade. Historical perspective Soda ash is used mainly in the manufacture of glass, soap, dyes and pigments, textiles, and other chemical preparations. All of these are the first basic consumer products produced by developing societies. About 3500 BC, the Egyptians became the first society to use crude soda ash. The soda ash was used to make glass containers. It was most likely obtained from dried mineral incrustations around alkaline lakes. Soda deposits were virtually nonexistent in western Europe. So people resorted to burning seaweed to obtain the ashes. The ashes were then leached with hot water and the solute was recovered after evaporating the solution to dryness. The solute, a crude "soda ash" was impure. But, it could be used to make glass and soap. These two products and industries were important to the population and economic growth of the region. About 11.5 t (13 st) of seaweed ash was required to produce about 0.9 t (1 st) of soda ash. Along the coasts of England, France, and Spain, seaweeds with varying alkali contents became important items of commerce and sources of soda ash before the 18th century. The LeBlanc process used salt, sulfuric acid, coal, and limestone. It became the major method of production from about 1823 to 1885. In the early 1860s, Ernest and Alfred Solvay, two Belgian brothers, successfully commercialized an ammonia-soda process to synthesize soda ash. It used salt, coke, limestone, and ammonia. The Solvay process produced a better quality product than the LeBlanc method. In 1879, Oswald J. Heinrich presented to the Baltimore meeting of AIME, a paper entitled "The manufacture of soda by the ammonia process." The paper compared the two processes and foretold the demise of the LeBlanc technique. World production of soda ash in 1880 was 680 kt (750,000 st). Of that, 544 kt (600,000 st) was produced by the LeBlanc process. Of the 2.8 Mt (3.1 million st) of soda ash produced worldwide in 1913, only about 50 kt (55,000 st) was by the LeBlanc method. The LeBlanc process was never used successfully in the US, except for a brief period from July 1884 to January 1885 in Laramie, WY. Previously, soda ash had been produced by burning certain plants, as exemplified by the early Jamestown colonists, or by recovering small quantities of natural sodium carbonate found in alkaline lakes, such as those found near Fallon, NV, and Independence Rock, WY. Before the 1884 startup of the first synthetic soda ash plant in the US at Syracuse, NY, most of the domestic soda ash demand in the East was met by imports, primarily from England. Large-scale commercial production of natural soda ash began in California in 1887 from surface crystalline material at Owens Lake. Production from sodium carbonate-bearing brines at Searles Lake began in 1927 (Fig. 1). In 1938, during exploration for oil and gas in southwestern Wyoming, a massive buried trona deposit, presumably the world's largest, was accidentally discovered. Recent mineral resource evaluation by the US Geological Survey and the US Bureau of Mines indicates that the Wyoming trona deposit contains 86 Gt (93 billion st) of identified trona resource in beds 1.2 m (4 ft) thick or greater. Additionally, there is about 61 Gt (67 billion st) of reserve base trona. Of this 36 Gt (40 billion st) is in halite-free trona beds and 24 Gt (27 billion st) is in mixed trona and halite beds. In 1953, the Food Machinery and Chemical Corp. (later shortened to FMC Corp.) became the first company to mine trona in Wyoming. Soda ash demand increased.

Jan 10, 1985

By W. Szymanski

The United States contains one of the world's largest reserves of uranium. Domestic production and exploration activities, however, have declined since the early 1980s due to weaker-than-expected growth in nuclear power demand and to foreign competition. The main result has been that more costly and less productive conventional mines and mills have closed. Meanwhile, industry productivity as measured by uranium output per employee has increased threefold since 1980. At the end of 1992, only six plants, all nonconventional, were operating in the United States. Due to cost considerations and increased environmental awareness, any additions to existing capacity are expected to be met through nonconventional in situ leach plants.

Jan 1, 1994

By Brendan Demich, Linda L. Chasko, Brendan Macdonald, Timothy J. Orr, Jessie J. Mechling, Cassandra Hoebbel, Jason Navoyski, William Helfrich, Jessica Cohen, Paul E. Schmidt, Jennica L. Bellanca

The National Institute for Occupational Safety and Health (NIOSH) in partnership with the Mine Safety and Health Administration (MSHA) developed VR Mine Rescue Training (VR-MRT). It is a training platform that allows mine rescue team members to explore virtual emergency scenarios collaboratively. Team members use a head-mounted display to visualize and interact together with equipment, hazards, and dynamic ventilation. All player actions are recorded and displayed for debriefing. Researchers at NIOSH demonstrated the training platform at various mine rescue competitions, including the International Mine Rescue Competition, and collected feedback. Participants’ responses were overwhelmingly positive. This paper describes the development of the software platform and the results of the usability surveys and interviews.

Jun 25, 2023

By Rameshwar Sah, L. R. Singh, SIVALINGARAJU BARISETTY, SHYAM YADAV, P. K. Ghorui

Fly ash is a by-product generated from combustion of coal in thermal power plant. Disposal of fly ash is a major environmental concern for the power plants. Though a considerable part of fly ash is used in cement making and brick manufacturing, substantial quantity remains unutilized. Silica and alumina are the major constituents in fly ash along with lime. Aluminosilicates and unhydrated lime present in fly ash, in presence of water, undergo a pozzolanic reaction and form cementitious bond which holds the particles together. Bentonite is commonly used as binder in micropelletization of process waste to attain the mechanical strength required for handling and transportation. The bonding of particles by bentonite is a physical mechanism, while fly ash bonding is a chemical mechanism. The present paper deals with the partial replacement of bentonite with fly ash in micropelletization without affecting the quality of micropellets.

Jul 30, 2021

By Rameshwar Sah, PK GHORUI, LR SINGH, SIVALINGARAJU BARISETTY, SHYAM YADAV

Fly ash is a by-product generated by the combustion of coal in thermal power plants. Its disposal is a major environmental concern for these power plants. Though a considerable part of fly ash is used in cement making and brick manufacturing, a substantial quantity remains unutilized. Bentonite is commonly used as binder in the micropelletization of process waste to attain the mechanical strength required for handling and transportation. The present paper deals with the partial replacement of bentonite with fly ash in the micropelletization process without affecting the quality of the micropellets. The mechanisms of both the binders are discussed. The bonding of particles by bentonite is a physical mechanism, while fly-ash bonding is a chemical mechanism. Silica and alumina are the major constituents present in fly ash along with lime. In the presence of water, the alumino-silicates and unhydrated lime present in fly ash undergo a pozzolanic reaction and form cementitious bonds, which hold the particles together. Use of fly ash as alternative binder for bentonite has cost benefits besides providing a better utilization option for fly ash.

By Earl M. Frizzell, Ronald W. Utley

Introduction For the past several years the Bureau of Mines has undertaken research to develop alternative mine material haulage systems that will improve mine productivity, reduce haulage costs, increase mineral availability, and conserve energy. One basic concept being pursued is a means for crushing primary blasted rock to a size that can be reliably and economically moved on conveyors. During 1980, mine requirements for this equipment and the capability of existing technology to satisfy these requirements were assessed. The study continued into 1981 on the basis that satisfactory equipment for this purpose needed to be developed. The objective of the 1981 program was to perform an engineering design of such a system. A mine survey and equipment development study was conducted in cooperation with the open-pit mining industry by GATX through its subsidiaries, Fuller Co. (a crusher manufacturer) and GARD Inc. (GATX's research and development center), under contract to the USBM. Results of a mine survey in the copper, iron, and molybdenum industries indicated that a universal crusher system could be developed even though details might vary from mine to mine. The crushing characteristics, including tonnages desired, were similar in all surveyed mines. Most mines had similar views about the desirability and frequency of crusher movement. The perceived need for in-nit crushing varied between copper and iron mining. The copper mines felt a greater sense of urgency for introduction of such a system, probably because typically greater vertical haulage is found in copper mines than in the iron mines. All mine personnel surveyed were interested in portable crushers and almost universally preferred gyratory-type primary crushers. They preferred large crushers, citing inherent reliability and durability, and the machine's relative freedom from clogging. Large size minimizes the number of crushers and conveyors needed. Analysis of desired crusher system characteristics (Table 1) fixed the crusher size at 1.5 x 2.3 m (60 x 89 in.). The 1.5-m (60-in.) feed-opening dimension could accept the largest material normally fed to the crusher, and the 2.3-m (894n.) head diameter could fulfill the 3.63 kt/h (4,000 stph) capacity requirement. Selected System Description The comments and analyses discussed in the contract report led to the design and refinement of a movable crusher system. This system represents the consensus of more than 100 mine workers and almost 50 construction and engineering company personnel. It is supported by more than 50 years of experience in crusher manufacturing. Although many alternatives are available for any given system, and selections are likely to be dictated by varying site conditions, the selected system is believed to be appropriate for most projected requirements. Final design would be dictated by mine operators during evaluation for approved projects. Detail design of the feed and discharge systems were not included in the study because they are mine specific. The basic system (Fig. 1) consists of a 1.5 x 2.3-m (60 x 89-in.) gyratory crusher on a structural steel frame. The frame is used as an operating platform for the crusher and as a carriage to move the crusher. The control tower includes a crusher lubrication room, a hydraulic equipment room, a switch gear room, a room for the motor control center, and a control room for operating the crusher and maintaining the equipment. The auxiliary system consists of a hydraulic rock hammer and pedestal crane with 74-t (80-st) and 14-t (15-st) hooks. Figure 1 also shows stairs, railings, and a work platform. Feed and discharge arrangements are shown on Fig. 2. The system shown is for mildclimate applications. Additional enclosure and heating would be needed for extremely cold weather conditions. Crusher A 1.5 x 2.3-m (60 x 89-in.) gyra¬tory crusher was selected for this application. This size can handle the typical throughput of 3-3.63 kt/h (3,500-4,000 stph) desired by the mines and the 1.3-m (50-in.) material to be crushed without difficulty. The crusher is the heaviest

Jan 4, 1983

By Richard E. Ellwanger

Methods of utilizing flocculants as settling and filter aids for mineral processing slurries are reviewed. Broad chemical classifications and techniques for proper dilution, multiple addition, and combination treatments are discussed. A variety of custom built and commercially available systems for make up and delivery of flocculants to the application points are in use through- out the mining industry. Those concepts which, in the author's opinion, are particularly important to the successful make up and use of flocculants are presented in relationship to the available make up and feed systems. Actual industrial applications are included in the presentation.

Jan 1, 1980

By J. W. C. Wong, S. D. Miller, J. J. Jeffery

Pre-mining identification of acid forming mine and waste materials is of concern to the mining industry because of the potential for the generation of acid mine drainage, acid rock drainage, and soil acidity problems. Accurate identification of acid forming material is essential for developing appropriate waste management strategies to reduce environmental problems related to acid generation from sulphide containing wastes. The acid-base accounting procedure, in its various forms , is commonly used for pre-mining screening of mine and mine waste materials. The procedure is generally effective when used and applied correctly but is prone to incorrect interpretation of results which can have significant financial and environmental implications. This paper examines the acid-base accounting Procedure and the possibility of misuse of this method with special emphasis on the sampling method, the sulphide forms, the acid neutralization capacity, and the interpretation of results. Data from numerous coal, base metal, and gold mining operations are used to illustrate the application of the acid-base account. The data base indicates that overall, approximately 1/3 of all waste generated by mining and mineral processing is potentially acid forming indicating the need for correct identification and management. Problems associated with simple application of 'absolute' acid-base criteria for classifying acid forming material are highlighted and the need for developing site specific or 'relative' criteria is discussed and illustrated by case study.

Jan 1, 1991

By Jonathan Ludlow, Robert A. Jankowksi

Introduction A longwall operator can make few changes to increase output, significantly reduce respirable dust, and decrease power consumption. Reducing drum speed, and thereby cutting with increased pick penetration, is one. This article defines the benefits of deep cutting in terms of reduced dust production and power consumption. It also identifies the practical aspects of high pick penetration in terms of shearer performance and coal loading. Before examining some practical aspects of reducing drum speed and looking at the theoretical background, it is worthwhile to summarize what is meant by high penetration and deep cutting, and what potential benefits and pitfalls may be expected. Deep cutting (in the sense of high penetration rather than wide web) can be defined in one or more of the following ways: • Cutting with an average pick penetration distance higher than that used in the past. • Cutting with a pick penetration higher than the longwall operator would have used if the advantages of deep and slow cutting were not considered. • Cutting with a well-designed shearer drum below 40 rpm. All these definitions are slightly arbitrary. They are given to provide a basis for discussion and to make the point that any move towards deeper, more efficient cutting can result in operational benefits. The benefits of deep cutting appear in many different areas. The most noticeable benefit, provided suitable instruments are available, is the reduction of airborne respirable dust. During an experiment on a longwall in the Pittsburgh seam, a nearly four to one reduction in dust levels was seen when drum speed was halved. Not all studies have shown such a big reduction, but it seems that some benefit is almost always obtained when drum speed is reduced. Production rate and specific power consumption are also affected (in a positive sense) by reducing drum speed or increasing pick penetration. Although these changes may not be as spectacular as those in dust level, they contribute to the economic return of the longwall operation. Similarly, improved washability through fines reduction may have a beneficial economic effect. Cutting with shearer drums operating at lower speeds does have some possible deleterious impacts that an operator should be aware of. For example, cutting reactions - loads imposed on the picks by the coal being cut - will be increased as a deeper cut is used. Steps must, therefore, be taken to ensure the stability of the shearer and provide an adequate haulage effort. These increased cutting reactions also result in higher loads on the power transmission system (gearboxes, ranging arms, pick boxes, etc.) from the shearer motor(s) to the pick tip. These higher loads must be anticipated and provided for with the necessary hardware. In particular, extra haulage power must be provided with low drum speeds, since haulage effort required increases roughly in proportion with pick penetration. Because the drum will be rotating more slowly or will have fewer picks, the load on shearer components will also be more variable. If suitable, robust equipment is not used, this increased vibration will decrease reliability. Benefits of Deep Cutting Lower dust levels, decreased specific power consumption, and improved product washability are the most noticeable benefits of reduced drum speeds. Although the benefits will vary greatly with mining conditions and the type of coal, some examples of what can be expected are described below. Reduced Dust Levels Figure 1 shows principal results of a study on the effects of reduced drum speed conducted on a longwall in the Pittsburgh seam (Ludlow, 1981). This figure shows that average dust production was reduced by about 70% when drum speed was halved. By making some assumptions about such quantities as coal density, it is possible to apply this proportional reduction to the quantity of respirable dust liberated per ton of coal mined. When this is done, two kinds of results are obtained: • At 70 rpm, about 1 g (15 gr) of airborne respirable dust is created for every ton mined (roughly one part per million). At 35 rpm, only 0.28-0.37 g/t (3.9-5.1 gr per st) of coal mined become airborne respirable dust. • At 35 rpm, nearly four times the amount of coal may be mined before the compliance level is exceeded, compared with 70 rpm.

Jan 3, 1984

By G. Deschenes, P. J. H. Prud'homme

A laboratory study was carried out to evaluate the effect of oxygen and lead nitrate on the recovery of gold by cyanidation of a free milling gold ore, which contains 0.4 % copper as chalcopyrite. Efficient gold extraction is achieved only under specific conditions. The recovery of gold was increased from less than 90% to up to 98% by addition of lead nitrate. In the pre-leaching, the kinetics of oxidation of soluble sulphides are not an accurate indication for the length of the treatment. Even though the consumption of cyanide was reduced due to the inhibition of the dissolution of chalcopyrite by increasing additions of lead nitrate, cyanide consumption had to the held above 1.85 kg/t to maintain good recovery of gold. The continued addition of lead nitrate above 300 git had no impact on the recovery of gold. It was also found that the addition of lead nitrate at the start of cyanidation gave the same performance as when added during pre-leaching. The addition of oxygen increased the recovery of gold by 1.5%. The concentration ofNaCN had to be maintained in the range of700 mg/L because of the high concentration of copper in solution. The recovery of gold dropped significantly when the average NaCN concentration fell below 640 mg/L. Application of the findings of the laboratory study at the industrial scale led to improved plant performance.

Jan 1, 1997

By A. J. Benham, H. Kessler

In the UK a high proportion of land-won sand and gravel is extracted from sub-alluvial gravels and river terrace gravels located within river valleys. However, extraction from deposits of this type is increasingly proving to be less acceptable. Quarries within river valleys often have a high visual impact and the cumulative impact of these operations in close proximity to each other can be high (figure 1). River valley operations are almost always restored to open water. Whilst these may be attractive for nature conservation and provide leisure activities, they can also have a serious impact on the natural hydrology of the flood plain. Wet restoration of quarries located close to airports or airfields can also lead to concerns regarding increased risk of bird strike on aircraft. The Civil Aviation Authority recently suggested that an exclusion zone of 13 km be applied around all airports and airfields to reduce the potential for bird strikes on aircraft. This action is likely to have a serious impact on the availability of potential sand and gravel extraction sites in river valleys.

Jan 1, 2005

By Nikolay M. Sirakov, Michael L. Feves, Rumen P. Mironov, Daniel R. Hack

Subsurface investigation of sand and gravel deposits has generally been limited to test pits and borings. These techniques are problematic in terms of the accuracy, usability, and cost of the final data. Innovations in the application of geophysics have been gaining acceptance in the aggregate industry, especially to determine depth to bedrock and the extent of uneconomic inclusions. This paper presents a system to optimize the processing and evaluation of electrical resistivity data. The system uses 3D separation, geometrical reconstruction, and visualization of subsurface objects.

Jan 1, 2002

By W. Wan

Diesel particulate matter (DPM) emitted from diesel engines is currently considered to be a health problem in underground mines. As a result, attempts have been made to control DPM both by reducing emission rates and by managing the DPM that gets into the mine atmosphere. This paper presents a method for modeling the generation, transfer and distribution of DPM in the mining sections through the use of a convection-based computer model so that controls for emitted DPM can be evaluated. A variety of ventilation strategies and diesel deployment schemes for room-and-pillar development sections were simulated to compare their effects on average DPM concentrations at several fixed and mobile personnel locations in the section. Input data for the model was gathered from actual diesel development sections and derived from experimental study results provided by other researchers. Studied using the model were ventilation schemes using vent tubing and brattice, exhaust location strategies on the vehicles, and the direction of ventilation at the feeder-breaker location. A summary of results from this study will be presented.

Jan 1, 1994

By E. B. Thorn

The production of portland cement requires that four basic elements -- calcium, silica, alumina and iron -- be ground to a fine powder, homogenized, and fed to the pyroprocessing unit, where it is burned to a cement clinker. The raw material must either be ground wet in a slurry form or dried and ground to a dry powder, with a fineness of approximately 85% passing the 200 M screen. According to the Portland Association's Plant Information Summary, approximately 38% of the U.S. capacity is ground wet and 62% ground dry. The following data is taken from the Portland Cement Association's 1981 Energy Survey: [Million BTU/Ton kW h/Ton Wet Process Plants 5.86 138 Long Dry Process Plants 4.97 123 Dry Preheater Plants 4.03 157 ]

Jan 1, 1984

By J. H. Kelley

In this paper, we show that the methane emission and the dust generation in under-ground mining currently and in the future pose operational, health and safety conditions which adversely Impact face productivity and worker satisfaction. One solution is the use of a dual-aircourse system of ventilation. In this concept, one aircourse captures and exhausts to the surface the dust generated and the methane emitted in coal/mineral fragmentation while a second aircourse provides workers with cleaner air for breathing and comfort. Various dual-aircourse configurations adapted to the Variable Wall Miner are analyzed and compared with conventional mining in gassy seams, indicating a marked reduction in the required air quantity and the number of aircourses.

Jan 1, 1996

By Tom Ireland, Sumi Eratne

The approach to Risk Management during the procurement of major projects often has a significant outcome on the ultimate successful delivery of a project. The $NZ4.4B Auckland City Rail Link project is the largest and most complex transportation project yet undertaken in New Zealand. Risk management prior and during procurement was undertaken in accordance the ITIG Code of Practice for Risk Management of Tunnel Works (TCoP) and through the use of an Alliance Geotechnical Baseline report. This paper describes the measures taken during the procurement process to achieve certainty with respect to outcomes and minimise project risks whilst also achieving value for money. This included the use of cloud-based delivery of geotechnical data and 3-D geological models, reducing tendering costs and allowing a focus on risk mitigation measures during the tender rather than data management.

Jun 13, 2021

By M. S. Klima, M. Fofana

The use of a laboratory-scale magnetic fluid-based separator for coal separations was examined. A Frantz laboratory magnetic separator was modified by fabricating new pole pieces of the appropriate geometry to provide the proper magnetic field gradients. Two separation chambers, which were constructed of Plexiglas, were designed to fit between the pole pieces. A commercially available, water-based, ferromagnetic fluid was used as the separating medium. The separating density was changed by varying the current intensity of the electromagnet coil. Both batch and continuous separations were made using 0.59 x 0.50-mm and 0.18 x 0. 15-mm coal. The results are compared to those obtained using organic liquids.

Jan 1, 1998

By J. D. Patsey, G. T. Lineberry

Introduction A computer program was developed for analyzing drum-type hoists before modifying an existing system or designing a new one. Its use permits the preliminary evaluation of a system before seeking technical assistance from mine hoist designers and manufacturers. The user-friendly program accepts a variety of data and analyzes hoisting systems for any balance state. The program can be used to calculate skip capacity to yield a desired production rate, solve for drum face width, select a permissible wire rope, estimate total horsepower of the hoist plant, and estimate annual power cost. Whether required for a large mining complex or for a relatively small operation, a hoisting system must be carefully designed to ensure the efficient, reliable, and safe flow of material. Because shaft sinking and hoist installation can total between 2.5% and 3% of the cost of opening a deep mine, proper hoist selection is critical. Today's mining engineer has at his disposal the most powerful design and analytical aid ever, the micro- computer. There is, unfortunately, limited software for the study of hoisting systems, unlike that for other materials handling equipment (Manula and Albert, 1980; Prelaz et al., 1964; Bucklen, 1969; Thompson, 1985). HOIST reduces a time-consuming set of calculations to a concise package of interrelated subprograms. A literature review revealed no common-user pro- grams to analyze hoisting systems, although at least four major hoist designers/manufacturers/installers have their own in-house programs. To provide a tool with which the mining engineer could preliminarily analyze a materials hoisting system or could check the calculations of a hoist contractor, a computer program was developed. HOIST was written in BASIC for the IBM-PC for ease of program adaptation and to en- courage field use on compatible systems. Details of program development are omitted, since the basic principles of hoisting analyses are relatively straightforward, simple, and readily accepted (Har- mon, 1973; Nordberg, n.d.; Adler, 1957). Program features, intended usage, and benefits of the com- puterized solution are emphasized over theory development and mathematical rigor. Background The mine hoist system that is selected and installed at a mine is the "lifeline" of that mine, with installations lasting 20 years or more. Thorough study is warranted to ensure that productivity demands are met at a minimum cost per ton. The increased cost of a large, powerful, high-speed hoist must be offset by increased production to justify its selection. To optimize this tradeoff, an extensive hoisting analysis should be performed. The analyses to properly size the skip (or cage ) , the drum, and the hoist drive are conducive to computerization, permitting rapid evaluation of changeable operating and design parameters, such as velocity, acceleration, state of balance, and productivity demand. The program is particularly useful in conducting sensitivity trials, such as investigation into the effect of change of productivity on skip capacity and on horsepower of the hoist drive. HOIST is currently limited to the study of drum-type hoists with cylindrical drum(s). However, only minor changes to the program would permit analysis of friction hoists and conical drum configurations. Model development and testing The program is based on accepted equations and physical relationships. Examples of manual calculations formed the basis for decision points and program branching. Data is input in the order that it would be needed if the problems were solved manually. The choices are arranged likewise. HOIST was developed in sections, with manual solutions performed to check program logic. The testing became more rigorous as sections were completed. Output from one section becomes input for following sections, as appropriate. The simplified flow diagram of HOIST is given in Fig. 1.

Jan 1, 1988

By A. E. Hall

The authors are to be commended for their attempt to provide a convenient piece of software for preliminary drum hoist specification. This field has received little attention in recent years and is eminently suited to calculation by computer. Unfortunately, there appears to be an error in the calculation of the required rope diameter. The 66-mm (2 5/8-in.) rope selected is oversized for this application. Wire rope weight and breaking strength are related to the rope diameter. For a round strand rope

Jan 1, 1988