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By Michel Dagbert

In the exploitation of porphyry-type deposits, the quality of the ore is mostly defined according to its grade. Besides the simplest distinction, ore-waste, several grade categories may exist and they correspond to the different ways in which the ore is further processed. At the time of mining the selection of the different categories is done from extensive information available from blast holes. But planning has to be done before this information is available and it is necessary for the geologist to forecast, from exploration and development data alone, the possible outcome of the selection done later on a block, a level, or the whole deposit and ultimately predict the ore reserves and value of the deposit. A good statement of this problem has been presented at the 1976 AIME annual meeting by Williamson and Hueller (1976). They have shown that, if the cut-off values are directly applied to the estimated grade of blocks, a gross overestimation of the recovered tonnage of ore (14%) will occur. This problem, now termed "the vanishing tons problem" (DaVid, 1977) seems to be common in many open-pit operations and it has been explained several times (DaVid, 1972; Huijbregts, 1975). In order to solve it l.Jilliamson and Mueller proposed a solution based on compiling masses and masses of blast hole data available from mined-out portions of the deposit. They derived empirical correction factors which provide for every block, given its estimated grade, the expected tonnage and average -grade of each category of material within that block. The purpose of our work is to repeat the same exercise but ignoring the blast holes data i.e. we want to derive the correction factors from the only DOH data. Doing this, we are more in the real conditions where the valuation of the mine and are reserve analysis has to be made before production actually starts. Two possible ways to achieve this goal will be investigated and the emphasis will be on recently

Jan 1, 1977

By Daryl E. Radcliffe

This report describes an instrument system developed by the Bureau of Mines to continuously monitor and record changes in roof displacement during underground mining activity. The instrument consists of a single-wire extensometer coupled to a mechanical-drive chart recorder mounted in an aluminum frame installed in the roof. The unit is small and simple to install and meets safety requirements for use in underground coal mines.

Jan 1, 1977

By David E. Siskind

Increased mineral consumption and environmental concern have caused much interest in potential damage and annoyance from ground vibration and airblast produced by production blasting in surface mines and quarries. Ground vibrations are traditionally blamed for "shaking the house to its foundations," but often the airblast is responsible, particularly when the distances from mine to structure are large. Simultaneous measurements of ground vibrations, structure vibrations, and indoor and outdoor noise from blasting are being used by the Bureau of Mines to determine the relative importance of the ground and airborne blast energy in shaking the structure and making windows, dishes, etc., rattle.

Jan 1, 1977

By Svenson D

Most exploratory drilling in the N.S.W. coal fields has been conducted using convent- ional diamond drill rigs of modern design, us- ually truck or trailer mounted. Conventional diamond drill rigs have also been used exten- sively by the Queensland Department of Mines for coal exploration. However almost all of the exploratory drilling of surface mine coal prospects throughout Queensland has been conducted using rotary rigs typified by the Mayhew 1000 truck mounted unit. The rotary rig has proved capable of both rapid non-core drilling and core drilling with high core recoveries when modern core barrels have been used by experienced drillers. For deep or continuous core drilling, wire-line equipment is now in general use. Both wire-line and conventional coring is effected using stationary split inner tube barrels, for minimum core disturbance, maximum core recovery, ease and accuracy of logging and sub-sectional sampling. Diamond core bits are generally required in N.S.W., with water circu- lation. In Queensland, the generally softer coal measures strata can be successfully cored using tungsten carbide bits and air circulation is the preferred method where possible.

Jan 1, 1977

By Whang K, Choi H

A study of flocculation of ultra-fine coal particles by ultrasonic waves was investigated on a laboratory scale.The coal suspension was dilute, with low ionic strength, and at pH 6·2.When a stationary sonic wave is set up in a solution containing suspended coal particles, it is believed that high and low pressure regions are alternately established at the half wave-length of the sonic wave and this resultsin the migration of coal particles towards the low pressure regions.As expected the flocculation is more effective as to frequency and the power of the ultrasonic waves is increased.The shape and size of the test equipment are also important variables.

Jan 1, 1977

By Joel D. Hammond

Lightweight concretes date back to before the Roman Empire. The earlier concretes were made by combining a burnt lime for cementious material with pumice or volcanic rock for aggregate. Although structural value was limited due to its primitive nature, many structures were able to withstand the test of time. The rotary kiln expanded shale industry had a slow start that began around 1908. The industry was founded by Stephen J. Hayde of Kansas city, Missouri. Mr. Hayde noticed that the bloating effects of some aggregates were undesirable by the brick industry. Material of this type was considered waste and avoided in brick production, but he realized it had all the qualities and basic requirements for a concrete aggregate that would reduce weight and still retain structural value. It came into national attention by use in ocean-going vessels through a shipbuilding program undertaken by the united states Fleet Corporation. This research was brought about by the need to find a suitable material to replace high-grade plate steel due to a shortage created by World War I. The need prompted the government to supply the reserves that Stephen Hayde desired to continue and complete research into producing a uniform lightweight aggregate. His results pointed to the rotary kiln method for which he was granted a patent in 1918. One of the most famous and largest concrete ships built through this program was the U.S.S. Selma. Although the Selma

Jan 1, 1977

During the period January 1, 1977 through July 31, 1977, 5 percent (264,000 tons) of U.S. capacity was closed due to power curtailments in the Pacific Northwest because of the shortage of water. During July, one plant in Tennessee cut production by 50,000 tons annually due to a power reduction by the Tennessee Valley Authority. Full capacity production was resumed at a West Virginia smelter during September. If demand for aluminum is strong it seems likely that aluminum supply during the remainder of 1977 and in 1978 will be tight. The price was increased 3¢ per pound to 51¢ per pound effective March 28, 1977, and by an additional 2¢ per pound to 53¢ per pound, effective July 5, 1977. New projects and expansion of existing facilities are planned by Australian aluminum companies over the next 2 to 3 years. The companies listed have committed themselves to spending approximately A$801 million: Alcoa of Australia Ltd. -New alumina plant at Wagerup, south of Perth. Darling Ranges bauxite is located near the proposed project. A$650 million. Coma 1 co Industries Pty. Ltd. -Increase bauxite mining capacity and upgrade or replace other facilities at its Weipa mines on Cape York Peninsula region of Northern Queensland. A$81 million. Alcan Australia Ltd. -Expansion program that will increase capacity of the Kurri Kurri aluminum smelter north of Sydney about 50 percent, and improvement of other facilities at the plant. A$70 million.

Jan 1, 1977

By Dipak C. Talapatra

This report describes the development of guidelines for design, inspection and maintenance of automatic couplers. In order to devise the guidelines, performance requirements for automatic couplers were carefully established. This was done through a comprehensive survey of coupler manufacturers and extensive observation of automatic couplers in service in a broad spectrum of mines. The capability of the couplers to withstand the demands of the mining environment in terms of strength characteristics, gathering range, curve negotiability, and other factors were all carefully evaluated. An analysis of coupler related accidents for the years 1972-1976 was carried out to provide information on the safety and reliability of existing automatic couplers. This formed an important input to the development of the guidelines. It is expected that these guidelines will be useful to coupler manufacturers for establishing designs for improved automatic couplers, and to mine operators for maintaining their couplers in a safe and good operating condition throughout their expected lifetime. This report is in two volumes: Volume 1 Technical Report Volume 2 Design, Inspection, and Maintenance Manual

Jan 1, 1977

By Bruce Maxwell

The deformation modulus of coal mine pillars theoretically can be reduced by drilling holes in advance of the mining face. This reduction of modulus along the edge of the pillar has the effect of decreasing the stress concentration in the roof; control of roof caving is thereby predicted. Initial field work indicated that a high horizontal stress field existed at the field test site: Subsequent field work was undertaken to confirm the high horizontal stress field and to attempt to relieve the horizontal stress in the immediate roof. A method of softening pillars in conjunction with normal mining activity was developed. Instruments to measure horizontal roof strain, roof parting, roof tilt at the rib, and changes in vertical and horizontal stress in the roof and in the coal were used. These instruments were installed in both softened and unsoftened entries and in locations to indicate the effect of vertical slots in the roof. Significant stress reduction due to pillar softening was indicated, but the effect of this reduction on roof stability was not established. The vertical roof slots relieved the horizontal stress in the immediate roof very effectively, and observations of roof conditions indicated that the slots definitely improved roof stability.

Jan 1, 1977

By Edward G. Cunney

Track in underground bituminous coal mines was investigated and technology was taken from other industries in order to obtain information on conditions that impair the safety and efficiency of the track and to develop guidelines and useful information on the construction, inspection and maintenance of mine track. Volume 1 contains information on the investigations, observed track conditions, useful technology from railroads and other industries, derivations of track condition descriptors and limits, conclusions, and recommendations. Volume 2, Guidelines, contains recommended standards and practices for mine track. It includes the relation of track conditions to safe speeds; descriptions and limits for measurable track features, such as gage; descriptions of conditions for track components that are normally not measurable, such as subbase soils; construction requirements and techniques; inspection requirements and methods; and methods for managing and performing track maintenance work. It does not repeat the summary or? derivations. Volume 3, Inspection Handbook, summarizes recommended standards and procedures from Volume II and provides related information for ready reference by inspectors in the mines. As a research product to be used in mines, it does not repeat the summary, derivations or references.

Jan 1, 1977

This Bureau of Hines report on underground mine communications addresses methods and equipment to meet the communication requirements of working sections and places of coal and metal-nonmetal mines. A review of the status of trapped miner detection is also presented.

Jan 1, 1977

By H. W. Breathitt

World demand for phosphate rock has increased significantly in the past fifteen years. Prior to the early 1960's, most of the world production was obtained from Florida, North Africa, and Kola. As the 1960's arrived, new mines in North Florida and Eastern North Carolina, as well as expanded production in the Western United States, .increased domestic production. Many new mines overseas have also become significant. This includes countries such as Senegal, Togo, Israel, Spanish Sahara, and Jordan. Limited production, often as by-products, has been noted in South Africa, Brazil, and other countries. In recent years, and even recent months, we have learned of many new areas being considered as potential sources of phosphate rock. This includes Australia, Saudi Arabia, Mexico, Colombia, and Brazil. Many other developing countries have discoveries and are considering their new deposits, often with difficult beneficiation problems, as potential sources of phosphate. These factors all relate to expanded world, population and the demand for more fertilizer products to produce food. In this paper, four areas of the world with different types of phosphate deposits are briefly reviewed to contrast the ore beneficiation problems to Florida procedures--long considered the "standard" of the industry, at least for most of the United States' domestic production. Agrico has three large operating mines in Florida with total production capacity exceeding seven million tons per year. Here, pebble phosphate (+14 mesh material) is produced without the use of flotation, whereas all of the material finer than 14 mesh is subjected to flotation beneficiation to upgrade into high grade concentrates.

Jan 1, 1977

By K. H. Nimerick

Laboratory data and field tests indicate that substantial losses of valuable coal can be caused by wind erosion. Wind tunnel tests show the effects of wind velocity and particle sizing on the amount of coal lost while in transit. Different coals were evaluated to determine the variables associated with wind erosion. The erosion losses can be substantially reduced by using a binder, or crusting agent, to consolidate the surfaces of the coal into a solid mass which resists erosion. This not only reduces economic loss but minimizes pollution.

Jan 1, 1977

By Frederik P. Agterberg

This paper deals with frequency distributions in the field of mineral resource evaluation when a grid is superimposed on the study area and metallogenetically significant attributes are coded with respect to the cells of the grid. It is shown that the parameters of a negative binomial distribution for frequency of mineral deposits per cell can be derived from the parameters of a gamma distribution for the coded attributes. It is also shown that an exponential model for spatial correlation of cell values and Matheron's discrete Gaussian model for indirect transfer functions may provide a suitable methodology for relating cell value distribution to cell size.

Jan 1, 1977

By E. R. Dotson

Kaolin is an important industrial mineral. It has unique properties, which combined with its low cost, make it suitable for use in a wide variety of products. Kaolin is defined as "any of a group of clay minerals, including kaolinite, nacrite, dickite, and anauxite, with a two-layer crystal in which silicon-oxygen and aluminum-hydroxyl sheets alternate; approximate composition is AlZ03-ZSiOZ-1/ ZHZO".-The kaolin discussed here is composed chiefly of the mineral kaolinite. Kaolin is also commonly referred to as "china clay". Approximately 4.9 kkg (5.4 million short tons) of kaolin was sold or used in the United States, and .8 million kkg (.9 million short tons) was -exported in 1974. In domestic usage, paper coating and filling accounted for 43% of the total, fol-2/ lowed by refractories, rubber, and ceramics.-Figure 1 shows the amount of kaolin sold or used by domestic producers for specified uses for the years 1963-3/ 1973.- Kaolin was produced at mines in 14 states, but Georgia accounted for 75% of the 1974 domestic production. The average value for all grades was $36.00/kkg 4/ ($32. 67/ton) .-

Jan 1, 1977

By Johns D. R

The producers of mineral sands on the East Coast of Australia might be regarded as having a simple task of selling Rutile and Zircon. Such is not the case. Differing quality and grain size requirements plus the dramatic increase in the percentage of mineral sold in a processed form have meant a large increase in the number of different end products handled. The resulting sales control problems are compounded by the need to be able to deliver against a large number of separate contracts which may relate to spot or long term sales in small quantities or in bulk shipments. Methods of helping management control this situation have been devised and incorporated into a suite of computer programs. Experience with the approach has been very satisfactory. The effect of changes to shipping schedules, commitment to new or changed orders, or proposed changes to production can be evaluated as and when necessary with little bother. Confidence in decisions taken is high since the process of data collection has been designed to involve

Jan 1, 1977

By Joseph A. Kantor

Several wall rock porphyry or pyrometascmatic copper deposits occur within the metamorphosed Paleozoic formations along the northern and eastern flanks of the Little Dragoon Mountains. Rocks ranging in age from Precambrian to Recent occur in the area. The Tertiary age Texas Canyon Quartz Monzonite intruded the sedimentary section in the eastern half of the range metamorphosing the Paleozoic carbonate units to tactites composed of garnet, diopside, and tremolite. Copper, zinc, and molybdenum minerals deposited in sites which are structurally controlled and stratigraphically favorable. Because the deposits are covered by alluvium, the information on structure, alteration, and mineralization is based upon a study of the diamond drilling programs. The mineralized district can be divided into four areas: 1) The Johnson Camp copper-zinc deposits; 2) The Dragoon copper deposit; 3) The I-10 copper-molybdenum deposit; 4) The Strong & Harris copper-zinc deposit. On the southwest end of the range beneath alluvial cover, the Cretaceous Bisbee Group was thrust over Precambrian and Paleozoic formations. The Tertiary Texas Canyon Quartz Monzonite intruded and metamorphosed them. In the upper plate, the Cretaceous sediments near the intrusive were metamorphosed to metaquartzite and andalusite and sillimanite schists. In the lower plate the Martin and Horquilla formations were marbleized. The lower Abrigo was metamorphosed to epidote rich calc-silicate tactites and biotite hornfels. A composite geologic cross section, based upon diamond drilling,, through the Dragoon copper deposit is shown in Fig. 1. The geologic events which formed this deposit are: 1. A faulted section of Precambrian Pioneer formation and diabase and Cambrian Bolsa and Abrigo formations was thrust over Pennsylvanian Horquilla formation. The Dripping Spring quartzite if present, has not

Jan 1, 1977

By M. G. Manzone

Approximately two-thirds of the annual 210,000 tons at copper refined by AMAX Inc. at the United States Metals Refining Company in Carteret, New Jersey, comes from a wide variety of copper scrap ranging from low-grade smelter scrap to wirebar-grade material. The equipment and methods used to effect such large-scale metal recycling in an urban area and the measures taken to collect and recover metal values from smelter and refinery byproducts while protecting the environment from pollution are described and discussed.

Jan 1, 1977

By Frederick Bloetscher

An improved parachute-type stopping for changing the course of mine ventilation air during mine emergencies has been developed by Goodyear Aerospace Corporation for The Bureau of Mines. The stopping can be quickly deployed by one man from a single attachment point and provides excellent stopping performance with the flow in the design direction. Adding pin and foam attachments between its skirt and the passage-way surfaces improves its performance with flow in the design direction and maintains the stopping with zero or reverse air flows. Stopping performance results for a range of airway sizes including 7.5 X 10 ft simulated airway with pressure differentials of up to 3.0 inches of water are presented. Predicted performance values for this stopping design for larger passageways are also presented.

Jan 1, 1977

This Bureau of Mines publication presents five papers given at a Technology Transfer Seminar on Metal Mine Fire Protection Research. Several seminars are held each year to bring the latest results of Bureau conducted and sponsored research to the attention of the mining industry as quickly as possible.

Jan 1, 1977