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By J F. Carswell, G Cheshire

The Pajingo gold operation in Queensland is approximately 55 km south of Charters Towers and 134 km south-west of Townsville. The gold deposit was discovered on the northern end of the Drummond Basin in 1983 and first open pit production began in 1986. Mining progressed underground in the 1990’s and gold production peaked in the early 2000’s as the main Vera/Nancy lodes were extracted, producing 330k oz in 2003 (a record at the time). More recently, as Ore Reserves and grade have diminished, the mine has had to develop innovative mining practices to maximise recovery of the remaining Mineral Resource. This has included a modified sublevel caving method against previously mined/backfilled zones. The method has been coined modified sublevel shrinkage (MSLS). Full scale trials of the new mining method have been successfully completed. This has allowed the site to revaluate the Mineral Resource and include areas into the Ore Reserve that were once deemed sterilised, adding significant value to the operation and extending its life-of-mine. This paper describes the first of two large scale MSLS trials and key operational learnings from it.

Mar 15, 2021

By ERNEST F. . SURCEIARD

work have been published from time to time by the Survey.' A detailed report on the Birmingham district, with maps, has been completed, and will be published within the next year." In the following paper it is aimed to present only an outline of the geologic relations of the ores, since the Appalachian geology of Alabama has been discussed by many previous writers, but to describe rather fully the ore of the Birmingham district, and to discuss its relations and probable extent. IT. OUTLINE OF THE GEOLOGY. 1. Stratigraphy. The pre-Pennsylvanians rocks exposed in and along the borders of the valley-regions of Alabama, range from middle Cambrian to Mississippian (Lower Carboniferous), and at the SW. extremities of the valleys these rocks are overlain by coastal-plain deposits of Cretaceous and Tertiary age. A generalized section of the pre-Pennsylvanian Paleozoic rocks for the valley-regions is given in Table I. TABLE I.-Section of Pre-Pennsylvanian Paleozoic Rocks in Valley-Regions of Alabama. System. Formation and character. Thickness. Ft. Shale and sandstone 300 to 2,200 Carboniferous (Mississippian- Limestone and shale 300 to 800) I Sandstone and shale 50 to 200 1 Fort Payne chert and limestone 100 to 300 Devonian Chattanooga shale 0 to 30 Silurian Clinton (" Rockwood ") shale, sand¬ stone, and iron-ore 200 to 700 Ordovician Chickamauga ("Trenton") limestone.. 200 to 800 Cambro-Ordovician Knox dolomite and chert 1 2,200 to 2,700 basal dolomite 500 to 600 Cambrian Conasauga shale and limestone 1,000" to 1,500 - I a Base not. exposed.

Nov 1, 1908

By Keith L. Harris

Recent data indicate a marginal decline in overall growth in world economic output from 3.1% in 1985 to 2.9% in 1986 (table 1),2, 3 Many nations experienced slower economic growth because of the huge trade imbalances existing between the United [ ] States and Japan and the Federal Republic of Germany, the U.S. budget deficit, and the growing Third World debt. Some developing nations, however, experienced booming growth. Declining prices for energy and nonenergy commodities and the fall of the dollar against the currencies of major industrial countries benefited several developing countries--energy importers and exporters of manufactured goods with currencies tied to the U.S. dollar, which were able to expand markets in the industrialized nations. The drop in commodity prices increased demand in industrial countries and depressed it in developing countries. Lower demand in the developing countries contributed to a decline in the real net exports from industrial countries. As a result, output growth in industrial countries declined from 3.0% in 1985 to 2.4% in 1986, despite growing internal demand, Average output growth of developing countries increased from 3.296 to 3.596 during the same period, however, primarily because of the low prices of their products and the strength of demand in industrial countries for those products. Developed country output growth was extremely uneven, however. For example, the economic output of nonfuel exporters grew 5.4% in 1986, while that of fuel exporters dropped 0.7%.

Jan 1, 1987

By John Wilson

This report describes the performance of Phase I of a project to design, analyze, and demonstrate a multilift longwall mining method applicable to mining coal seams twelve (12) feet or more in thickness. A non-simultaneous multilift operation is the most viable thick seam mining technique for introduction to the United States coal industry. In the case of the proposed site at Emery, Utah it will result in an increase in coal extraction from 30% with present methods to at least 50% and possibly more. The major technological advance involved in this project is mining a lower lift under a previously mined upper lift. To accomplish this, entries must be developed and maintained beneath the upper lift gob. This will necessitate the use of steel supports at frequent intervals throughout the lower lift' entry system. This has not been done in the U.S. to date. An economic analysis of the project indicates that, while this method will result in a higher than average cost per ton for coal mined, the coal would be competitive with current-operation in the area.

Jan 1, 1976

By Robert McClure, Frederic Leclercq, Ricardo Chavez

With significant vibration control and fragmentation challenges facing them, the CBS quarry (department of the Nord) successfully integrated a technical partner and mine to mill optimisation to deal with a difficult environment. For the last three years, CBS has been conducting a global production monitoring program similar to the mine to mill concept used in the mining industry. This concept consists of optimising the drilling and blasting while monitoring the effects on the downstream chain (vibration control, loading, hauling, crushing, plant output). Blast optimization is ensured by systematic control of the blast geometry (volumes, patterns, bench and face anomalies, drill deviation) and by the use of constant specific energy blasting. Constant specific energy optimises the work of the explosive in a blasting operation and, when combined with a high accuracy programmable electronic blasting system, reduces the impact of blasting on the environment and enhances blast performance. These techniques ensure consistent blasting results and hence improved site productivity. The improvements achieved have been identified thanks to an effective system designed to monitor the key production parameters.

Jan 1, 2007

By D. Harrington

The mining industry of the United States has-long been severely criticized because of its high rate of accident occurrence, net only as compared with other major industries-in the United States but also with the mining industries of other countries particularly Europe. Statistics (often not of strictly comparable nature) indicate that the accident-frequency rate in all mining is currently about three times and the accident-severity rate is about seven times as great as the average for general industrial work in the United States. These figures are by no means comforting to humanitarian mining men, irrespective of their status in. the industry, and they constitute a challenge that certainly cannot continue to be ignored much longer. This picture becomes much darker when the above statistics are augmented with data indicating that. on an exposure basis our mines (more particularly our coal mines) have accident rates two, three, or even more times as great as more or less similar types of mines in Europe, particularly England and Wales, Belgium, France, and Germany. However, these foreign accident statistics should be carefully analyzed before we become very mush concerned about them, because they are clot strictly comparable owing to several considerations, not the least of which is the fact that foreign methods of compiling or recording accident statistics often differ materially from ours. Moreover, foreign mining and other conditions axe definitely dissimilar to ours in many if not most phases, and numerous ether factors affect the comparability of foreign mine-accident statistics with ours. Unquestionably it should also be taken into consideration that the accident rate of the 130,000,000 or more constituting the populace of the United. States as a whole is much higher than that of any other major country in the world and is two, throe, or more times the rate of the European countries that have more favorable mine-accident rates than those of the United States. Moreover, it is significant that the mine-accident-severity- rate of British mines is about six times the average accident-severity rate of the major industries of the British Isles, or but little mere, favorable than the comparable figures in the United States, namely, that mining-has an accident-severity rate about seven times that of the average of about 30 of the major industries of this country.

Jan 1, 1941

By S H. Begg

There is strong evidence that many major oil and gas (O&G) projects are plagued by large cost and schedule overruns, or significant underperformance in productivity. Similar evidence exists for large mining projects. This paper claims that uncertainty is the underlying reason why projects fail to deliver the metrics used to justify their investment, or to deliver the economic value possible if alternative decisions had been made.Most technical and economic analyses are performed to reduce uncertainty to help make decisions. Decision-making is about ranking alternatives and choosing the best; rarely are precise predictions required, if this is even possible. Better uncertainty assessment is one of the keys to better decisions, thus better business outcomes. To get better decisions it is suggested that the focus or reward/penalty incentives be shifted away from the quality of outcomes to the quality of decisions. High-quality decisions are those that are generated from the skilled use of the tools, methodologies and processes from the discipline of decision analysis.Uncertainty is quantified by probability, which is a degree of belief in the truth/falsity of some proposition about a quantity relevant to a decision, such as volume of in-place resource, future price or action of a competitor. The probability a person ascribes to a proposition depends upon their information set; hence probability is subjective – it is not an inherent attribute of the quantity of interest or the physical system.The above simple observations have profound implications for modelling approaches, how they deal with uncertainty, the use of data to help assess uncertainty and the reliability of information provided by subject-matter experts. The limited circumstances under which frequency data (from spatial or temporal variables) can be used to assign probabilities is also reviewed.People, in general, are subject to a range of biases and cognitive errors. Research with O&G subject-matter experts shows that their expertise offers little or no protection from making errors in probability assessments and other judgements.CITATION:Begg, S H, 2016. Decisions, decisions – uncertainty, variability, modelling and psychology, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 9–18 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

1. Domestic Production and Use: In 1974 twelve companies operated 31 primary aluminum reduction plants, three firms accounting for 64% of production. Washington, Oregon, and Montana accounted for 32% of the total production; Gulf Coast States, 24%; Northern States, 33%, and other Southern States 11%. Output of primary metal in 1974 was valued at $3.4 billion. About 80% of the secondary recovery was from new aluminum base scrap and 20% was from old scrap. Aluminum consumption by 25,000 firms was centered in the East Central United States. Of aluminum consuming industries in 1974, building accounted for about 27%; transportation 19%; electrical, 13%; packaging, 15%; and consumer durab1es, 9%.

Jan 1, 1975

Real economic growth for 1988 may fall short of the 3.3% projected by the Department of Commerce in August 1988 because the summer drought and intense heat in many areas curtailed output more severely than expected. The economy grew at an average annual rate of 3.0% for the first three quarters of the year, slowing in the second and third quarters. Export growth, which occurred even as the dollar edged up compared with other industrial country currencies, was an important factor in the expansion. Notable gains were posted in sales of machinery, computers, aircraft, chemicals, and telecommunications equipment. Imports increased, but not as much as exports, and the U.S. trade position was still much improved from that of 1987. Personal consumption expenditures grew slightly faster than the economy as a whole. Purchases of consumer durables showed notable strength in the first half of 1988, but slowed down in the third quarter. Despite the moderate rise in interest rates, business spending for new plant and equipment also rose and contributed to 1988 gross national product (GNP) growth. Both new business investment and export demand spurred orders for U.S.-made machine tools. Orders for machine tools for the first 8 months of 1988 were almost triple those in the corresponding period in 1987.

Jan 1, 1989

The criterion for assessing the accuracy of coal reserve estimates proposed by Philip and Watson (1982) is criticized.Following Royle (1977), it is suggested that the global estimation variance found by geostatistical methods is more appropriate.This method is applied to coal data from the Bowen Basin. This shows that two factors (the inherent variability of the variable under study and the total number of drill holes) have more influence over the accuracy of the reserve estimate than the form of the drilling pattern. Comparisons between the relative errors for different sized regions demonstrate that the spacing between drill holes is of secondary importance. The dominant factor is the total number of holes.Comparisons between the relative errors show that some variables such as sulphur need a much denser sampling than the others to obtain the same level of precision.

Jan 1, 1983

By R. Luchese de Moraes, J. A. Matthews, C. Feliciano Bruzual

The role of biomass char in blast furnaces has been re-examined by scientists worldwide, as a feasible option to reduce the carbon intensity of ironmaking. This contribution makes a technical and economic analysis of the ferro gusa industry in Brazil, with the last 172 charcoal-Blast Furnaces operating in the world. A key strategic question is presented: what is the current status and future prospects of biomass use in Blast Furnaces? Findings provide significant implications to metallurgists: while ferro gusa from charcoal is regarded as carbon neutral iron with low impurities, there are limiting factors that hinder the further proliferation of charcoal-BFs: biomass generation requires vast extensions of arable land and aggregates have low production capacity. Additionally, most of the charcoal is presently generated in beehive kilns with low yields. These elements combined make charcoal-hot metal expensive in price. With respect to the future prospects of biomass, the injection of small biochar particles through the PCI rigs in BFs (here coined Bio-PCI) and iron ore sintering may offer a practical alternative to significantly reduce the CO2 emissions in the ironmaking process.

Jan 1, 2015

By Nicholas P. Callas

This report presents research results obtained in the investigation of deviation control of boreholes in the rotary drilling process. The approach taken in this research is the passive method of placing stabilizers in the bottom-hole assembly to control deviation. Extensive use was made of the drill string mechanics theories of Lubinski and Woods. Analog, digital and hybrid solutions to variety of boundary value problems were investigated in order to determine the best models for bottom-hole assemblies. Field drilling data was analyzed and the results obtained from various models were compared to the actual drilling results. Various accomplishments of this work have been published in open energy industry literature, with more publications to follow.

Jan 1, 1981

By Matheus Teixeira Fraga

É comum o uso de modelos matemáticos no intuito de prever a qualidade do coque, sendo a maioria dos modelos atualmente disponíveis baseada nas propriedades dos carvões. Para este trabalho foram feitas misturas binárias e ternárias de carvões com variados teores de matéria volátil, a fim de se produzir coque em escala laboratorial. A reatividade ao CO2 em termobalança e resistência mecânica em tambores foi avaliada. Dois modelos para previsão de indicadores de qualidade do coque foram avaliados, o modelo aditivo e o modelo de interação. A partir da metodologia desenvolvida em laboratório foi possível produzir, avaliar e comparar coques feitos a partir de diferentes carvões e misturas. O modelo aditivo mostrou uma boa capacidade de prever a reatividade dos coques. No entanto, para os índices derivados dos testes de tambores os valores calculados mostram uma diferença importante em relação aos experimentais, indicando interação dos carvões no processo de carbonização. Nos resultados do modelo de interações, os valores calculados para reatividade e resistência mecânica, se comparados com os resultados do modelo aditivo, mostraram uma melhora na capacidade de previsão da qualidade do coque. O modelo de interações se apresenta como uma ferramenta interessante na seleção e mistura de carvões.

Aug 17, 2017

By Sandra K. Zacharias

Brass, a deliberate alloy of copper and zinc, has been known since before Roman times. There are two main methods of making brass: (1) Cementation or calamine process - crushed zinc ore (calamine, ZnC03 , or calcined calamine, ZnO), is mixed with charcoal and small pieces of metallic copper and heated to about 900°C in a closed crucible, (2) Alloying - metallic copper and zinc are melted together in a reverberatory furnace. According to most modern authorities (e.g. Smith and Forbes 1955), the calamine process was the only one used in western Europe prior to the 18th century. At that time, the alloying technique began to take over, because metallic zinc was successfully produced on a large scale for the first time. Previously, this had been a problem because zinc vapourizes at 906°C or about the same temperature at which it can be reduced from its ore. Thus, some means had to be devised to collect and condense the zinc vapour (Tylecote 1976). Metallic zinc was known, however, earlier than the 18th century A.O. Several early finds have been made, including a rolled sheet of metallic zinc found in excavations at the Athens Agora dating to the 3rd to 2nd century B. C. (Farnsworth et al. 1949). The Chinese were producing zinc by at least the 10th century A. D. and, by the 17th century, Chinese zinc ingots were being imported into Europe by the Dutch East India Company (Needham 1974). Metallic zinc is also mentioned in several European documentary sources from the 16th century (e.g. Paracelsus, Agricola). This study traces the changes in Western brass making methods from Classical to Renaissance times by examining documentary and archaeological evidence.

Jan 1, 1999

By P. K. Chatterjee, G. D. Just

Sublevel open stoping is a low-cost method that has been successfully employed in many large underground mining operations. Where ore body characteristics are suitable, extensive mechanization and the use of large-scale stoping techniques can considerably reduce operating costs. However, careful long-term planning of mine layouts and large capital commitments in development are required prior to production. Implementing precise mine design procedures and carefully controlling operations can result in considerable benefits. This article describes methods to achieve these objectives based largely on mining operations at Mount Isa, where sublevel open stoping has been used since 1932. Ore won by this method accounted for a very large percentage of the total tonnage produced at Mount Isa. Major costs associated with sublevel open stoping can be classified as drilling, explosives and charging, and LHD costs. In this article, analyses of these costs are made with particular reference to stope design. Parameters such as burden, drill hole diameter, explosive density, specific charge, etc., are considered in establishing the interrelationship of unit operating costs, as well as total costs of sublevel open stoping.

Jan 10, 1981

By AIME AIME

SCRIPTURE, statistics and imagination all were drawn upon by the speakers who acclaimed Daniel C. Jackling as recipient of the William Lawrence Saunders Gold Medal for 1930. The award was made at a special dinner at the Ritz-Carlton, in New York, on Oct. 31. Lafayette Hanchett, old friend and associate, said that if it were his task to compress the life story of Daniel Jackling into a single sentence, he could find noth¬ing so appropriate as these words from the 22nd Chapter of Proverbs, "See'st thou a man diligent in his business, he shall stand before Kings." Mr. Jackling's diligence, according to the speaker, his love for his task, have been outstanding in his career. W. S. Boyd, now ranking official in the Jackling organization, cited amazing statistics as to the quantity of copper supplied to industry by the four "porphyry". coppers that are under Mr. Jackling's immediate direc¬tion, as well as by those that, in a sense, owe their existence to the pioneer work at Utah Copper. In the aggregate- 16,000,000,000 lb. of copper having an approximate value of $2,700,000,000 have been produced from disseminated ores since 1905; and of this total 42 per cent came from Utah and the Nevada group. Newcomb Carlton, president of the Western Union Telegraph Co., long an admirer of Mr. Jackling, adroitly drew a picture of a similar occasion in some 'foreign country. He imagined Mr. Jackling being raised to the peerage and whimsically addressed him as Sir Daniel, the Right Honorable Earl of Bingham!

Jan 1, 1930

Dry weather since the third week in January has set back any prospects for an early increase in hydroelectric power in the Pacific Northwest, according to The Bonneville Power Administration. The 25% cutback made in July probably will not be restored in March or April. Noranda Aluminum, Inc., increased its price for 99.5% aluminum ingot from 66 cents to 70 cents per pound effective March 1, 1980. Revere Copper & Brass, Inc., also -increased its price for primary aluminum from 66.0 cents to 70.0 cents per pound effective February 1. Kaiser Aluminum & Chemical Corp. raised its international price for 99.5% primary aluminum from 72.6 cents to 82.6 cents per pound, c. i. f., effective February 26 on new orders and on shipments from March 15.

Jan 1, 1980

By M. A. Schellhardt

In recent years development of instruments and equipment for determining subsurface pressures and temperatures in. gas and oil wells has made it feasible to obtain information that eras not available in the past on many gas-production problems. The material presented in this report illustrates particularly the value of subsurface-temperature data in the study of subsurface leakage from gas wells. An abnormal decline in the shut-in pressure of the Lone Star Gasoline Co. A. Jones No. 1 gas well in the southern part of the Buffalo (Tex.) field was observed during an interval when a negligible volume of gas bras being withdrawn from the reservoir. Wellhead-pressure readings indicated that the shut-in pressure of the well declined from 2,295 pounds per square inch gage on February 3, 1937, to. 1,445 on February 12, 1935. Tests conducted by engineers of the Lone Star Gas Co. suggested that the subnormal pressure gaged on February 12, 1938, probably was not caused by a head of liquid in the well.

Jan 1, 1940

The first metal-mine accident-prevention course was prepared and published in 1942--45 as a series of seven miners' circulars (Nos. 51-57). The scope of the course has been broadened, revised, and brought up to date, and it is being published as a similar series of seven miners' Circulars (Nos. 51-57, revised) on accident prevention in metal and nonmetallic mines. These circulars are: Accident Statistics (Miners' Circular 51), dealing with general statistics on accidents and injuries at metal and nonmetallic mines, including causes, costs, and the uses of investigations and reports of all accidents.

Jan 1, 1957

This report presents information developed during Bureau of Mines contract H0242016, "Mine Shaft Fire and Smoke Protection Systems" from May, 1974 through June, 1975. Purpose of the metal and nonmetal health and safety project was to evaluate mine shaft fire and smoke hazard problems, and to develop and demonstrate a low-cost, reliable mine shaft fire protection system that would protect against such hazards and would be applicable to a majority of metal and nonmetal mine shafts, including raises and winzes, especially in deep mines. Program effort proceeded through five phases, culminating in the successful in-mine fire demonstration of a prototype system. In addition to this final report, a film is available which depicts components of the system and its successful shaft fire testing at an underground mine.

Jan 1, 1975