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By J. A. Bleeck

A discourse on the relationship between industrial minerals and paper production, concentrating on high grade, ultra fine ground calcium carbonate (mean particle size less than 2 microns) and precipitated calcium carbonate. The scope of the paper encompasses four basic areas relevant to the topic: 1. A tutorial overview of the papermaking process with an examination of various industrial mineral components in that process; 2. A discussion of basic technological topics pertinent to the utilization of carbonate in paper with emphasis on the relative aspect. Of natural ground calcium carbonate (GCC) and synthetic precipitated calcium carbonate (PCC); 3. An overview of paper and carbonate market, in both the United State, and Europe with emphasis on (a) current status and future growth trend. Of such market., and (b) discussion of the major influences on growth and development of such market.; and 4. Identification and discussion regarding the principal producers in calcium carbonate markets serving the paper indu.try in Europe and North America.

Jan 1, 1993

Introduction The frigid regions of Canada's high arctic islands are well-known for major oil and gas explorations. But mining leads the way in development. Cominco Ltd.'s Polaris mine is in its second full year of commercial production, and outstripping the rated production capacity foreseen by its planners. The Polaris mine is located on the shore of Little Cornwallis Island, near the settlement of Resolute Bay. The mine property is compact. It occupies about 3 km2 (0.5 sq miles) of the vast Arctic landscape. A number of mining and technological firsts were necessary to bring a mine into production at this 76° North latitude. Development constraints that had to be overcome included climate, remote location, and the limited ice-free shipping season. Construction of the entire process plant and ancillary facilities took place on a barge in the South where labor and supplies are plentiful. The plant was towed through ice-strewn waters to its permanent location at the mine site 1450 km (900 miles) from the North Pole. Freighters moved the first shipments to the South during ice break-up in late summer 1982. Most of the zinc concentrate is sold to European smelters. The remainder is tolled at a custom smelter in Europe, and the resulting metal is sold by Cominco. Lead concentrate is sold to European smelters. The mine was designed to produce 177 kt/a (195,000 stpy) of zinc concentrate and 41 kt/a (45,000 stpy) of lead concentrate. Actual production in 1983 was considerably greater, with both mill throughput and feed grades being higher than forecast. Production was 217 kt (239,300 st) of zinc concentrate and 51 kt (56,300 st) of lead concentrate. Average milling rate was 2.3 kt/d (2500 stpd), well above the designed capacity of 2.1 kt/d of (2300 stpd). Arctic Climate Extremes The climate is typical of the Arctic: very dry with short, cool summers and long, cold winters. From November through February, there is continuous darkness. Continuous daylight prevails from April to August. Precipitation is light, rivaling the Sahara desert at about 127 mm (5 in.) of rain and snow a year. An almost continual wind forms deep snow drifts against any obstacle on the ground. Temperatures range from a winter low of about -50°C (-58°F) to a relatively pleasant 15°C (59°F) during sunny days in August. Freeze-up begins in September and ice thickness increases from less than 0.3 m (1 ft) in early October to a maximum of about 2.1 m (7 ft) in May. The permanently frozen ground extends to a depth of about 427 m (1400 ft). Only a few inches of surface ground thaws in the summer. Exploration Activity Zinc-lead mineralization was

Jan 10, 1984

By Robert W. Gordon

The art of excavating tunnels with continuous, full-face boring machines began almost 90 years ago, in the early 1880's. At this time, Colonel Beaumont designed and manufactured a seven-foot diameter tunneler for boring under the English Channel, Despite the absence of modern materials and manufacturing techniques, Beaumont's tunneler, powered by compressed air piped in from the surface, was quite successful. During its short, but impressive existence, this machine set a record of advancing in chalk 50 feet per day for 53 days - which is impressive even by today's standards. Despite the apparent success of this early tunneler, almost 80 years passed before any further significant development was accomplished in this field. Demands from the construction and mining industry and society itself have motivated the development of the modern tunneling machine. Our rapidly growing civilization needs faster, less expensive and safer means of excavating tunnels. Space age technology and materials have played a major role in making hardrock tunneling machines possible.

Jan 1, 1970

By Leslie E. Apodaca

INTRODTUCTION The use of spiral concentrators for processing fine coal particles is an old idea that has recently gained acceptance in the 11.S. coal industry. It was not onti1 the Australian Minerals Industry developed a spiral concentrator specifically for separating coal from ash in the latter 1970's and early 1980's that spiral concentrators were seriously considered as viable equipment for processing fine coal. The Wright Coal Spiral was introduced in 1980, the Mineral Deposits Limited Mark 10 Coal Spiral was introduced in 1982, and the Vickers Wyong Coal Spiral was introduced in the latter part of 1984. Each spiral design was different and utilized constant profile troughs, constant pitch troughs, compound profile troughs, and various splitter arrangements. Mineral Deposits Limited has combined the best features of the compound profile trough and constant pitch trough with critically-placed splitters to develop the MDL LD4 spiral concentrator which is a truly efficient coal washing spiral. This spiral concentrator was introduced into the U.S. Coal Industry in 1987. Recently, Mineral Engineering Technology of the United Kingdom and Multotec of South Africa have introduced their own coal spiral designs. Spiral concentrators were first installed in fine coal processing circuits in the Australian, South African, and Canadian Coal Industries in the early 1980's and in the U.S. Coal Industry in 1985. SPIRAL CONCENTRATOR SEPARATION PROCESS The separation process that occurs within the spiral concentrator trough is very complex, as it is a combination of three gravity separation processes. When the coal slurry first enters the spiral trough, each coal and ash particle and the water is subjected to centrifugal forces. These forces cause the water, light coal particles, fine heavy ash particles, and medium middlings particles to the outer vertical portion of the spiral trough. The coarse ash particles and the coarse middling particles remain on the inside of the spiral trough. The center or transitional area of the trough contains a mixture of middlings particles and near-gravity material that is present in the slurry, as shown in Figure 1. At the same time the coal and ash particles are suhjected to centrifugal forces, the trough design (both profile and pitch) causes the particles to be subjected to flowing film and stratified bed separations. The combination of these three separations, whose efficiency is dictated by the spiral troogh design, will effect the separation of the lighter coal particles from the heavier ash and middlings particles. As the slurry flows down the spiral, the profile and pitch design of the trough will counteract the centrifugal forces on the fine, heavy ash particles and fine middlings particles and cause them to migrate from the vertical portion of the trough to the center or inner portion of the trough. At the same time, any heavy particles trapped in the transitional area of the trough will be forced to migrate to the inner edge of the trough and any coal particles will be forced to migrate to the outer edge of the trough. SPIRAL SPLI'TTEP ARRANGEMENT The critical placement of splitters along the inner edge of the trough for removal of the heavy ash particles as the slurry flows down the trough further enhances the separation of the coal particles. At the bottom of the spiral trough are product splitters arranged to make a final separation of the slurry stream into clean coal, middlings, and refuse products.

Jan 1, 1988

By Howard G. Coopersmith

Kelsey Lake kimberlites are a cluster of eight diamondiferous pipes that occur in the northern State Line kimber lite district of the Colorado-Wyo¬ming diamond province (Coopersmith 1991, 1993) (Fig. 1). This is located at the southern margin of the Wyoming Archean province. Two relatively large pipes and a few smaller bodies define the cluster (Fig. 2). The Kelsey Lake kimberlite cluster has been developed as the first diamond mine in the United States. The cluster was discovered in 1987. Full-scale production began in the spring of 1996. Mining has produced gem-quality diamonds up to 28.3 carats in size. The 30 State Line kimberlites, intruded about 390 million years ago into Proterozoic crystalline rocks, were presumed to be underlain by Archean basement of the Wyoming Province. Nearly all the kimberlite pipes contain diamond but only the Kelsey Lake pipes are economic. The Kelsey Lake kimberlites contain predominately diatreme facies kimberlite, with minor hypabyssal and crater facies rocks locally occurring. Alteration and weathering of the kimberlites is extensive. Petrologic studies indicated an underlying lithosphere that has a largely Proterozoic signature and shows evidence of deep melt and metasomatic events. Current development has concentrated on the two largest pipes. These have been bulk-sampled after geological study (1987) identified the presence of small diamonds and mineral chemistry indicating favorable diamond conditions. A 10-t/hr (11-stph) rotary pan plant was established in 1992 to process thousands of tons of bulk-sample material. Grades and gem-quality diamonds to 14.2 carats in size were recovered. Early in 1995, it was decided to move from evaluation to commercial mining. Production began in early 1996. A 195-t/hr (215-stph) rotary pan plant was built. A water supply system and tailings disposal have also been incorporated. The project straddles the Colorado/Wyoming border. Existing mining permits were amended to incorporate the increased scale and new plant facility. The permits for this project included the following: Colorado mining permit, Wyoming dozing permit, Corps of Engineers Section 404, Colorado NPDES, Wyoming NPDES, Storm water Management Plan, Air Pollution Emission Notice, various Colorado and Wyoming State Engineer and well permits, Substitute Water Sup¬ply Plan, Larimer County Special Use Review, and US Forest Service road use permits. The temporary destruction of a wetlands area was a sensitive issue. It has been addressed through the Clean Water Act Section 404 permit administered by the US Corps of Engineers. This use will be mitigated by creating new, self-sustaining wetlands in the immediate drainage system. A comprehensive and bonded reclamation plan is incorporated in the permits. Diamond mining and ore processing is environmentally benign. No chemicals are used in processing the diamonds. The plant is a water wash facility. The kimberlite ore is inert, as is the granite wall rock. The exposure of the ore body and the subsequent ore processing and waste rock and tailings containments pose no threat of release, leaching or dispersion of any detrimental elements. There is no acid-forming waste. Even a prolonged acid rain environment will not produce a harmful leachate. Slimes containment and clarification ponds will prevent unacceptable levels of suspended solids in water discharge. The isolated, restricted access and nonvisible nature of the mine and processing has led to straightforward permitting. Geology The State Line district is located in the northern

Jan 1, 1997

By K. A. Grace

K.A. Grace's article advocates usage of the terms describing resources as defined by the US Bureau of Mines (USBM) and the US Geological Survey (USGS). Originally recommended in 1943, the terms were revised in 1976 and again in 1980. Mr. Grace further recommends that the term reserves should be severely restricted and that it should encompass mining and processing factors. The list of references quoted in the article does not, however, mention the study concerning reserves that was made over a period of almost four years by a joint Committee on Definitions. This committee was sponsored by three societies - the American Institute of Mining, Metallurgical, and Petroleum Engineers (AIME), the Society of Economic Geologists (SEG), and the American Institute of Professional Geologists (AIPG). Most of the detailed work was done by a working party appointed by the Society of Mining Engineers (SME) of AIME. After studying previous definitions in the US as well as in the United Kingdom, Canada, Australia, France, and other European countries, the following definitions were proposed and accepted in 1974 by the SME board of directors. (Ore reserve definitions in Rhodesia, South Africa, or New Zealand were not mentioned as having been reviewed.) Table 1 lists definitions from MINING ENGINEERING, July 1975. Notice in Table 1 it was mentioned, under Resources, that the definitions of reserves were recommended for the purposes of commercial evaluation. It was further stated that the terminology adopted by the USBM and the USGS, as released to the public, covering resources, was recognized as such. Mr. Grace also recommends that reserve calculations should allow for future losses in ore tonnage, ore grade, milling, and smelting. Unfortunately, it might take years to develop a prospect after it has been discovered. Mining methods have to be tested before being finalized in order to know what tonnage of ore is going to be lost, or how much dilution is likely to occur. The same problems are present in concentrating or in smelting. Operating mines usually know how mined grade compares with ore reserve grade. They can usually predict fairly closely what their final metal recoveries are probably going to be. It is, however, expecting too much to have to delay quoting reserves from say a recently drilled prospect. Any responsible mining geologist or mining engineer (or company for that matter) should state several things about an ore reserve calculation: that it is or is not a preliminary estimate only; that estimated grades have not been diluted to allow for a future, as yet unknown, mining method; that metal recoveries are or are not only tentative, based perhaps on drill hole samples only or on no metallurgical testing at all. Reserves of a partially explored prospect are always quoted when it becomes necessary to raise capital. If they are described as preliminary only (really just tonnage and grade estimates and not true "reserves") in addition to being accompanied by some of the items just mentioned, nobody is going to be misled. If, on the other hand, a report by a member of the SME or SEG is intentionally misleading, the individual must be reported and eventually disbarred from his or her society. To summarize, let us stay with the definitions of ore, ore reserves, and related terms as recommended and accepted by SME. I might add that on occasion I have used a fourth category in my ore reserve calculations, namely Geologically Possible Ore. This category is more or less the same as Inferred ore defined by the USBM and USGS. I have never given a grade to this category, which may be based only on geological mapping, geochemical sampling, or geophysical traversing.

Jan 8, 1985

By Ivano Andreis, Giovanni Valent

The Yindaruqin Irrigation Project is designed to irrigate 57,000 ha of land in the central part of Gansu Province of People's Republic of China. Water for the Project will be diverted through an 87 Km long feeder canal which will convey 36 cubic meters per second from an intake on the Datong River. (Fig. 1) The feeder canal consists of approximately 10 Km of open channels, 75 Km of tunnels and 2 Km of siphons and aqueducts. This is the biggest self-flowing irrigation water control project in the Northwest of China and it is among the most interesting projects in China for the geological and environmental conditions. Nearly half of the investment in the Project is a World Bank Loan and contractors were chosen by means of international bidding. The Italian Company, CMC Ravenna, succeeded in answering the bidding for the construction of tunnels 30A and 38, perhaps the most difficult in the Project, submitting a TBM alternative to the conforming drill and blast contract recommendation.

Jan 1, 1993

By T. Yalcin

It is well recognized that machine type and machine characteristics play vital roles in the successful application of froth flotation in mineral processing. Since the early 1900s, a multitude of machine designs have been and are still being introduced in an attempt to improve flotation efficiency. Machines based on mechanical agitation have been the most dominant in industrial practice. However, in recent years there has been a growing interest in pneumatic flotation units because of their claimed simplicity, low cost, high throughput and good metallurgical performance. This work was carried out to assess the effectiveness of pneumatic flotation on a magnetite ore. The method was applied using a prototype pneumatic flotation device that utilized a suitable nozzle for bubble generation. Important variables of the process were examined and optimized, including the nozzle size, air flow rate and froth thickness. Further tests were conducted to determine the influence of frother dosage and to explore the improvements that could be made on concentrate grade and recovery by cleaning and scavenging. Under the best test conditions, an iron concentrate was obtained with a grade of 66.4% Fe and a recovery of 97.7%. Particularly, the recovery was superior in comparison to that of mechanical flotation. This was attributed to the ability of pneumatic flotation to create and maintain a relatively thick froth layer.

Jan 1, 2002

By Richard Newcomb

It is four years since the seminal study of demand for rapid excavation by the National Academies of Sciences (NAS) and Engineering outlined this technology's opportunities, requirements and significance to the challenges of urbanization and natural resource conservation. The demand study was quite simple. Opportunities were valued at market while requirements to produce new technologies were valued at cost. The significance of new technology in economic terms was measured by the net discounted gains to users over time. The Academy view in 1968 was that these gains, even most modestly estimated, appeared large enough to justify the bill for research proposed by that Committee (1). In 1970 the question of demands became international in what is recognized as the first international experiment in technological policy analysis, terminating in the Advisory Conference on Tunneling of the Organization for Economic Cooperation and Development (OECD)(2). A monumental demand survey formed the basis for its economic assessment. The twenty-two OECD nations also made an impressive attempt to measure the magnitude of existing research and development efforts. In their recommendations periodical statistical demand forecasting and collection of demand data (Recommendation 1) was given central importance for public planning (Recommendation 2), the financing of public construction (Recommendation 3) and the encouragement of technological advance (Recommendation 4). Their program for international cooperation led to OECD's establishment of a Directorate for Environmental Affairs, and influenced the organization of the World Environmental Conference meetings now held in Stockholm under United Nations auspices. The OECD Conference was the first example of "an attempt to apply the concept of technological policy analysis to a 'civilian' technology having potentially

Jan 1, 1997

By G. Bloomsburg, R. E. Williams, S. D. Vincent

A modeling scheme is developed to simulate the hydrogeologic effects of mine design and development in unsaturated rock. Simulations are conducted using the UNSAT2 finite element computer program and hydrogeologic data from the site of a proposed mined-out waste repository at Yucca Mountain, NV. Results of the simulations are analyzed for: •variations in the direction of ground water flow and in the distribution of pressure head caused by the design of the mined out openings; and •mine design variables that affect the predicted rates of mine water inflow. Evaluating the hydrogeologic impacts of mine design and mine development in unsaturated rock is significant in several respects. Characterization of the preemplacement of wastes along the fastest path ground water flow system at the Yucca Mountain site has been a primary research effort. Ultimately, however, the degree to which waste isolation is achieved will depend largely on the post-mining hydrogeologic environment as altered by the mine design and on the radionuclide inventory and resulting heat effects of the repository. Therefore, an ongoing characterization of the proposed mined-out nuclear waste repository at Yucca Mountain, NV, is recommended. Modeling results indicate that: •mined out openings will affect the movement of ground water, both in rate and direction; •hydraulic effects of mine development depend on the hydrogeologic environment and on mine design geometry; •mine water inflow is possible in the unsaturated zone, even for mines developed in hydrogeologically homogeneous rocks; and •mine water inflow can occur at values of down ward flux that are appreciably less than the saturated hydraulic conductivity of the overlying rocks.

Jan 1, 1991

By M. Zuckerberg, E. Mader, R. Pasyar

We describe a new software product designed for the net present value optimization of multi-open-pit blended ore operations in which it is desired and/or necessary to dump some or all of the waste rock produced in the course of operations back into the voids created in the process of ore extraction. The software product simultaneously decides over the entire life-of-mine which material to mine in which year, once mined what to do with it, and where to put that material which it has decided to waste, all subject to annual blend and capacity constraints.

Jan 1, 2007

By Mike S. Ness, Allan G. Provost

High speed drilling, mucking, and hauling equipment was used in driving approximately 2.16 km(7100 ft) of lower power tunnel in quartz diorite for the Tyee Lake Hydroelectric Project near Wrangell, Alaska. The .91 m(36 in.) guage rail mounted equipment included a Tamrock 2-boom electric/hydraulic drill jumbo, a Haggl and 8HR mucker , and 3 Hagglund 115C shuttle cars. Several other innovative techniques allowed maximum advance rates of up to 17.5 m/day(57ft/day) in the 3 m(10ft) horseshoe section. Average tunnel advance was approximately 11 m(day(35.4 ft/day). The primary difficulties preventing full utilization of the equipment potential were the operators' "learning curve", the need for complete retraining of all personnel in the new methods, and minor sections of faulted ground.

Jan 1, 1983

By L. G. Wilson

In order to comply with time limitations imposed by this symposium, a very narrow but nonetheless interesting segment of the market has been chosen for discussion of the preparation of a tailor-made product to meet a specific need, and in view of the fact that the barite market is one of the oldest and one of the broadest non-metallic mineral markets in the world, it is necessary that we place this in perspective. Of a recent world annual production; (i.e., 1966 figures released last year in MINERALS YEARBOOK), of some four million tons, the United States consumed over 1/2 million tons, of which approximately 950,000 tons were produced domestically and approximately 700,000 tons were imported. Of this total, something approaching 90% was used for drilling-mud weighting, and of the balance, all but about 60,000 tone is consumed in the production of glass, barium chemicals, aggregates, and other minor uses; thus we are really taking a look at a very minute, however important, and very selective, portion of the total barite-market. The real meat of this paper, after eliminating all irrelevant uses of barite, and delineating the area of discussion, resolves itself into the approach to a favorable marketing area and a specific attack on that area. Cost, to the user, has been, patently, a function of distance, as the basic price of barite has varied very little over the years until recently, and freight rates have been the governing factor. Conversely, the seller of barytes must make concession in the plant price to compensate for distance, if he is to successfully compete.

Jan 1, 1969

By D. S. Saxena, Jack K. Tuttle

Lack of understanding of useful applications of explosives on construction work stem primarily from the fact that explosion is commonly associated with destruction. On rock excavation and other construction works a certain quantity of explosive is harnessed to perform useful work at the source e.g. blasts to disintegrate rock. Development in rock blasting techniques, including the use of multiple-row blasting with short delay ignition, have made it impossible to excavate rocks close to or below buildings even in closely built-up areas. To permit the use of explosives on construction projects, in ways that will not damage existing structures, guidelines have been developed from careful measurements of intensity of ground vibrations. Accurate electronic instruments are now available for doing this. PLANNING AND CONTROL Blasting operations must be carefully planned and carried out to avoid discomfort to persons or damage to property. This increase in the use of rock blasting in city areas alone has led to a number of problems due to ground vibrations, air shock waves, and the psychological effect of noise. While the latter seldom if ever causes damage, it does create irritation and discomfort to persons living or working near the blasting sites. A result of this is a steady increase in the number of complaints in respect of damage to houses and other premises. Many such complaints are genuine and damage may undoubtedly be caused when incorrect blasting techniques are used.

Jan 1, 1997

By J. Köppel, K. Kovári, Ch. Amstad

INTRODUCTION The measurement of displacements in soil or rock in the vicinity of underground openings provide valuable information for a better understanding of the behaviour of the structure. On the basis of systematic observations conclusions can be drawn concerning - safety of the opening in the various stages of excavation - effectiveness of the support measures - nature of the rock pressure to be expected - influence of the construction of the opening on neighbouring structures (settlements of foundations, underpassing other tunnels etc.) - comparison of theoretical predictions with the actual structural behaviour (1). Today there are several types of suitable instruments available that can be employed at reasonable costs for such investigations (2). The most important ones are the multiple point borehole extensometer, the inclinometer and the multiple point borehole deflectometer. As is well-known, the extensometer only measures the displacement component in the borehole axis, while the inclinometer and the deflectometer provide monitoring of rock mass movements normal to the borehole axis. In the following a new instrument is described, which has been given the name Extenso-Deflectometer ISETH. In this single piece of equipment certain features of the above-mentioned three types of borehole instruments are incorporated. it enables the measurement of all three components of the displacement vector at consecutive points along the borehole, the axis of which may have any direction in space. This device is portable like the inclinometer. A simplified version

Jan 1, 1979

By Donald V. Fites

The evolution of open-pit mining has been rapid during the last two decades. The development of larger, more productive and efficient equipment has been one of the key factors in this open-pit advancement. Selection of the proper equipment and its correct usage is paramount to successful operation while maximizing return on investment. The quantity of material being moved prior to mining the saleable product is increasing at a significant rate. For example, at a southwestern copper mine more than two hundred million tons of over- burden have been removed prior to exposing an ore which contains less than 1% copper. A recent survey of twenty-three Western Hemisphere copper mines reveals the average strippingratio was 2.2:l with a range of 0.9-8.5:l. In the face of increased mineral demand, the resulting technological developments and rising overburden to ore ratios, many open-pit mines now use totally different concepts for the removal of ore and overburden. An increasing number of these concepts now being installed include wheel tractor scrapers as a major part of the material handling system for unconsolidated overburden removal. To say scrapers move only unconsolidated overburden is incorrect. On the contrary, ripped phosphate rock, copper ore, iron ore, and moderately consolidated overburden are also being moved by scrapers in various areas of the world. As reported in the Minerals Year- book, however, about one-half of the material moved in metal and non-metal mines is never drilled and blasted or broken by other means. We will, therefore, in this paper, concentrate on the role of wheel tractor scrapers in unconsolidated overburden; the area of greatest usage.

Jan 1, 1969

By Fred V. Carrillo

California was the leading state in industrial mineral production value with an estimated value of nearly $2 billion. In total value of U.S. non-fuel mineral production estimated for 1992 by the U.S; Bureau of Mines, California ranked second; 81 % of California's total production value was derived from industrial minerals. California led all other states in the production of boron minerals, portland cement, diatomite, calcined gypsum and construction sand and gravel, and ranked second in potash and soda ash production. California's five leading industrial minerals in terms of value were portland cement, construction sand and gravel, boron, crushed stone, and soda ash. California had 13 additional industrial minerals production with reported sales of over $1 million including; industrial sand and gravel, magnesium compounds, lime, salt, potash, natural sodium sulfate, clay, feldspar, crude gypsum, pumice, dimension stone, calcium chloride and perlite.

Jan 1, 1995

By Pasi Latva-Pukkila

Underground rock drilling has gone through intense development during the last 25 years. Mechanization and hydraulics have greatly increased the efficiency of drilling and improved the environment of the drill operator. As the total economy has become more and more important, the development has resulted in greater overall economy in drilling. The latest evolution step is computerization of drilling equipment. Computerization has been applied to tunnelling jumbos, long- hole drilling rigs and bolting rigs. With today's technology computerization is the natural way to increase capacity and productivity of the drilling process. However, it is still impractical to implement total "robotic" drilling. In computerized drilling the operator's role continues to be vital in controlling the drilling process and in analyzing the effect of individual parameters on the whole excavation process. Today this is called "CAD" - Computer Aided Drilling.

Jan 1, 1989

By Zhang Zhitie

The limitations in mechanism research of mineral comminution in the past and the basic features of the comminution process have been analyzed. Two kinds of catastrophe model, i.e., cusp model and swallowtail one in the mineral comminution have been put forward. The dissipative structure of the mineral comminution: entropy production rate, extra entropy, extra entropy production and system stability has been discussed. The physical nature of the behavior that an old structure was destroyed and a new one was produced in the mineral comminution process has been brought to light.

Jan 1, 1995

By H. T. Mulryan

Talc is used as an essential ingredient in a variety of plastics applications ranging from polyester body patch compounds through polypropylene automotive, appliance and household furniture components to high performance parts made from liquid crystal engineering resins. This paper focuses on polyolefin applications, the three-tier market for talc in polypropylene, the effects of various tales in typical compounds and trends in each market segment. Emphasis is given to emerging markets, examples of which are polypropylene compounds that mimic higher cost resins, and polyethylene films. Customer requirements, for tales for these purposes are discussed.

Jan 1, 1993