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By D. Saramak

The proposal of the nip zone angle determination in HPGR crushing process is presented in the paper. Knowledge of the nip zone angle value, in turn, makes it possible to determine the real maximum pressing force in the high-pressure comminution. Two methods of determination of this maximum pressure were proposed and verified. The first method is based on the roll?s geometry, and the change of the HPGR chamber?s volume together with the roll rotation, while the second one considers the outlet gap width impact. Results of the nip zone angle calculations according to both methods are similar and show convergence with the real operating conditions. The verification was carried out in a piston-die press, and experimental results show that methodology of the nip zone angle determination presented in the paper has its practical confirmation. A proper determination of the nip zone border makes it possible to calculate the comminution probability of given type of material and is a basis for the HPGR crushing process modeling and optimization. Keywords: HPGR, comminution, nip zone, ore processing

Sep 1, 2012

By A. G. Doll

The Bond low energy impact (crushing) work index test is specified to be performed on rock specimens between 50 mm and 75 mm in effective diameter. NQ-diameter drill core, frequently used in mineral exploration programs does not meet that specification, it being 45 mm diameter or less. This paper reports the effect of performing the impact test on contiguous sections of HQ diameter and NQ diameter core, exploring the hypothesis that the contiguous intervals give equivalent results in spite of the core diameter difference.

Jan 1, 2012

By B. M. Davis

The uncertainty associated with a reserve estimate has generally been expressed as a subjective ranking rather than a quantitative expression of either reliability or uncertainty. These rankings of estimate reliability have taken a very nonquantitative bent as well. For example, the U.S. Securities and Exchange Commission definition of proven reserves is given as: Reserves for which (a) quantity is computed from dimensions revealed in outcrops, trenches, workings, or drill holes, grade and/or quality are computed from the results of detailed sampling and (b) the sites for inspection, sampling and measurement are spaced so closely and the geologic character is so well-defined that size, shape, depth and mineral content of reserves are well-established. (U.S. SEC, Form S-18, Item 17A)

Jan 1, 1992

By T. Kontos

Rogers Group, Inc., is the nation's largest privately held aggregates producer (primarily producing crushed limestone and secondarily sand & gravel) and a major regional asphalt paving construction contractor. The company also has interests in building supplies and coal. Facilities are concentrated in five states in the central U.S. (Ohio, Indiana, Kentucky, Tennessee, and Alabama), with an additional location in Southwestern Virginia. At the request of its then CEO and with support from the company's ownership, Rogers embarked on a strategic planning program in late 1986 by retaining an outside management consulting firm. The ultimate goal of this program was to develop a self-sustaining strategic planning process to inject a strategic dimension into every manager's business thinking and to improve company performance. Since then, Rogers has internalized the outside consultants' strategic planning framework --initially, using it wholesale, and later, greatly streamlining and tailoring both the planning process and product to meet the specific needs of the company. Implementation of strategies developed from strategic planning has resulted in significant improvements throughout the organization. The latest product of the strategic planning effort is a company-wide (or, "corporate") strategic plan that carries the theme of "Market Leadership through Excellence". This paper provides a case study of successful corporate strategic planning by examining the evolution of strategic planning at Rogers and by summarizing the key elements of a sound planning process and product.

Jan 1, 1994

By John Arrell, James Stuart

We have developed a tester that is uniquely able to measure the no-fire power level of certain types of electro explosive devices (EEDs). In the past, it has been difficult to establish a no-fire power level for nonlinear conductors, such as semiconductor-bridge (SCB) EEDs, and conductive-mix EEDs.

Jan 1, 2011

By Joseph B. Smith

I work as the Bureau's Liaison Officer for Colorado and am one of 38 Bureau employees who are stationed, for the most part, in state capitals across the nation. These offices serve all 50 states and Puerto Rico--some being assigned more than one state. Our primary task is to seek ways to achieve a closer and more productive relationship between State agencies and the Bureau of Mines. In 1970, when the Bureau initiated this nationwide system, our activities were limited to mineral supply operations. The potential of the program was soon recognized and Liaison Officers became the personal representatives of the Director and responsible for con- ducting the business of the Bureau that is best handled at the local level. Knowledgeable in the total operations of the Bureau, Liaison Officers are a primary point of contact for the public and for you to obtain information and, again, for you to provide the government with insight into the difficulties you have in providing this nation with an adequate supply of industrial mineral materials.

Jan 1, 1975

By John Hansen

This paper has been written for presentation at the 103rd Annual General Meeting of the Canadian Institute of Mining, Metallurgy, and Petroleum, April 29 to May 02, 2000. The paper addresses blast pattern fragmentation and diggability versus the blasting technique used. RESUME The author is the Vice President for Thunderbird Mining Systems. In this capacity he manages the mine site installation of surface mining mobile equipment monitoring and navigation systems. These systems are onboard instrumentation and software systems designed to: ??measure and log mobile equipments? production and health; and ??direct the equipment operators via onboard displays that show comprehensive maps and engineering instructions. The author is a mining engineering graduate from the Royal School of Mines. His work experience includes front line supervisor and mining engineer for Hudson Bay Mining & Smelting, mining engineer for Teck Corporation, and mining consultant for PriceWaterhouseCoopers.

May 1, 2001

By R. E. Salvoti

IN underground coal mining, the increasing trend towards mechanical methods is ever apparent. Figures for 1939 showed that 28 per cent of the total bituminous coal production was mined mechanically 1940 statistic will reveal an even higher figure. Factors causing this trend are varied, but the important are the following;

Jan 1, 1941

By August Ferraz Ribeiro, Guilherme Dias Mendona, Paula Henrique Lisboa, José Silvio Corsini

Correct slope adhesion is related to the conformity of the slope’s real geometry to slope planning. It is very important in mining because slope design has economic and safety implications. Slope design conditions can interfere with mining waste and ore proportion. Without a correct wall, the development of the mine can be hindered, which can reduce the amount of ore available. Furthermore, correct slope design reduces the possibility of melting and allows traffic with equipment and people in the mine. However, defining the wall is a more complex work as the characteristics of the rock require the use of blasting techniques. Therefore, Enaex Mining Technical Solutions (EMTS), in partnership with the engineering team at the Chapada Mine, at Lundin Mining, has developed this study in order to increase slope adhesion. The basis of this study is a near-field vibration test, which enables the creation of vibration attenuation law, and a seed wave damage model has allowed the characterization of the rock present at the Chapada Mine. Then, we could compare the model result to the real slope adhesion achieved with the buffer technique used in the mine. Therefore, it was possible to relate the real result to the model result.

Feb 6, 2023

By J. Fred Johnson

MORE ORE is mined in the Bingham District than in any other mining district in Utah. In addition to the open-pit operations of the Utah Copper Co., there have been, many large underground mines. Until recent years the principal production was from the Jordan and Commercial limestones, but in the last eight years valuable ore deposits have been developed in the so-called alphabetical or "A," "B," "C," and "D" limestones, mainly by the U. S. Smelting, Refining & Mining Co. The value of these developments has led the company just mentioned to acquire large holdings in the district and within the last year to install at the Niagara shaft a hoist capable of going to a vertical depth of 4000 ft., or 1800 ft. deeper than the present lowest level. Ore from Bingham has been the chief factor in enabling the

Jan 1, 1934

By George T. Hansen

WHY try to find oil in Utah? Why try to find oil anywhere? Isn't there too much oil already? Answers to these questions involve general oil conditions but are pertinent to my subject. In the first place oil produced in Utah up to the total amount of local consumption would not be subject to nor concerned with the national oil situation. An oil field in this State capable of producing up to 15,000 bbl. per day would have a large value and prompt realization. In the sec¬ond place, there is not too much oil nationally although the markets have been upset temporarily from time to time. Petroleum is so necessary and is in such general demand that an oil field anywhere, anytime, is a valuable and live asset. The oil business in general shows the best condition of any major industry. It has never been hit as hard as most industries and 1932 was a large improvement over its low spot of 1931. It can be and probably will be the one to lead the country back into business stability. Consumption of its products has been reduced less than that of any other important commodity. There are good and valid reasons why it should have been making a normal profit continuously. It has the oil and the processes and the facilities and the policies and the consumption of its products. There is only one reason why it has not been profitable recently and that is the lack of intelligence of from five to ten per cent of the producers. An op¬erator lacks intelligence when he cannot see that it is better for him to sell one barrel of oil at $1 than two or three barrels at 25 or 35c. per bbl.

Jan 1, 1933

By Dever C. Ashmead

COAL companies in the anthracite region are studying various methods of mining that will permit a considerably shorter life of gangway and therefore a decrease in the maintenance charges. Maintenance charges in the upkeep of gangways where the measures are steeply pitching are high due to the excessive cost of the replacement of timbers and the cleaning up of falls. Therefore, if the length of gangway in the coal beds can be decreased and the mining more concentrated, the life of the coal gangways will be decreased and consequently the maintenance charges will be lower per ton of coal produced. Customary practice in the anthracite region is to drive long coal gangways and to work the breasts as the gangway from which they were driven is advanced.

Jan 1, 1925

By AIME AIME

AT A meeting of the Boston Local Section of the Institute, on Oct. 3, approval was voted to the work done by its representatives on the Committee opposing the passage of a bill by the, Massachusetts Legislature to license engineers. The report is as follows: The Joint Committee on Licensing of Engineers, which included a Committee of the Boston Society of Civil Engineers and representatives of seven other societies,* submitted to the members of the respective societies, on Jan. 8, 1921, a report in which it was stated that on Jan. 4, 1921, a petition was filed in the Legislature of Massachusetts by the Boston Chapter of the American Association of Engineers accompanied by a bill to provide for the registration of professional engineers and land surveyors. This report also stated that at a meeting of this committee, held on Jan. 7, 1921, it was voted:

Jan 1, 1921

By Joseph Jensen

CURTAILMENT of oil production in California began in 1922 and 1923 when certain of the major companies completely shut down some pumping properties. Efforts of this kind were generally carried on without coordination by individual companies until 1923. From May to August of 1923, oil production in the Los Angeles Basin was curtailed because of lack of pipe-line outlets. This work was handled by a small committee of executives and engineers of some of the pipeline companies without any established. Method such as obtains at present. Not all of the major companies participated in ibis curtailment and the effort was not well organized. The problem then was principally to move the oil. The crisis passed in September of 1923 from then on the major companies each on it own initiative, shut in additional production. At Domiuguez, in 1921, Shell, Union and Associated agreed to limit drilling to a 100-ft. zone for one Near. In the summer of 1925, operators at Ingde-wood agreed to limit developments to a 1300-ft. zone during the 1925 drilling campaign. In the summer of 1927, the Ventura operators cut back their production one-third and deft it thus for 90 day. Drilling in this field has always been at a slow and conservative rate.

Jan 1, 1932

By C. E. Williams

THE Iron and Steel Division, A.I.M.E., is unique in this country in that it serves all phases of the iron and steel industries. Through its publications, its meetings, and its sponsorship of new technical developments in the industries, it has proved of great value. The various technical committees of the Division are the nucleus around which this service can be developed. The Blast Furnace and Raw Materials Committee has done excellent work. The need for beneficiation of iron ores is increasing and the economics of this operation are developing more and more in favor of increased activities. Ores that are slightly undergrade should be concentrated up to grade to supplant the present practice of mixing with higher-grade ores to bring up the average composition. Marginal ores that are not now being mined, or that are being mined and piled for future use, should be concentrated. The development of the use of sinter in the blast furnace, because of the elimination of fines, the advantage of better sizing of the charge, the resulting reduction of coke consumption, and increased output of pig iron per furnace, will make concentration and sintering become practical ahead of its natural time.

Jan 1, 1936

By William B. Plank

A NEW record-a quarter million students in the engineering schools of the United States and Canada-has resulted from the great demand for engineers following World War II. The figures released by the American Society for Engineering Education and which appeared in detail in the Journal of Engineering Education for January 1948, show that, on Nov. 1, 1947, 252,250 students were studying engineering in 149 engineering schools of both countries. There are 244,390 in the 143 schools canvassed in the United States, and 7860 in six schools in Canada. These figures include both undergraduate and graduate students and are therefore comparable with the figures in previous presentations on this subject. This unprecedented engineering student body

Jan 1, 1948

By N. H. Emmons

THE work of a consulting engineer or manager, when controlling mining-operations, requires that he have all the information concerning the mine in as concise a form as possible, and as the ore-reserves and their depletion and enlargement are the vital points to be studied, it is well to have them kept up to date and in some convenient form. The present paper describes a method adopted by me, which shows in a very clear manner the ore-reserves in a mine. The case illustrated is that of a vein near enough to the vertical for the vertical elevation of the mine to be the main working-map. A flat ore-body would be represented on a similar plat, but instead of the horizontal thickness of the vein being shown in the circles, the vertical thickness would be inserted. Fig. 1 represents an ideal longitudinal elevation of a mine, plotted in the ordinary way, using 100-ft. blocks and section-lines. In a mine where the block-numbers are posted by the engineer underground, the system of keeping the ore-tonnages extracted from the different blocks is easily maintained, and the actual tonnages of ore extracted can be kept so that the surveyor can have a check on his estimate from time to time. The ore-reserve sheet, Fig. 2, should be the same size as the map it is to accompany. Each square is used for the description of the ore-reserve in the block it corresponds to on the elevation. Where the section-lines cross the levels a circle is drawn, in which are written the widths of ore at that point, these widths being used in the calculations of each block cornering in the circle. It has been found convenient to show the figures in black in the lower half of the circle when the actual widths of ore are known, and when it is necessary to make up the figures of probable ore, as at the time of making

Jun 1, 1912

By C. K. Leith

THE resolution presented at the Annual Meeting of the A.I.M.E., calling on Congress to provide now for postwar accumulation of mineral stock piles under Government control, expresses, I think, the nearly unanimous view of the mining industry. As a result of the trying experiences of the first World War, Mr. Baruch, in his report of Dec. 24, 1919, to the President, urged that steps be taken at once to ensure adequate supplies of raw materials for future emergency. In the twenty years that followed, the same program was vigorously urged on Congress by many individuals and agencies, public and private, including the Secretaries of War and Navy, many members of Congress, the Bureau of Mines, the Planning Committee for Mineral Policy appointed by President Roosevelt, the A.I.M.E., the Mining and Metallurgical Society, and others.

Jan 1, 1943

By R. J. Cefalo

Blast and mining spillover between phases or critical areas of the pit is a continuing problem in the mining industry and a safety concern for operating mines. The challenge for many mines is to produce the highest value in the shortest amount of time for any project. For any project, the top priority of any mine is producing ore as fast as possible. The next challenge is to keep that ore feed continuous. To achieve continuous ore feed, pits are designed with multiple phases that are connected and are mined at different elevations. This difference in elevation causes dangers with spillover between the phases during mining, drilling, and blasting. This paper covers an incident that occurred at an active mine and the work completed in creating a spillover control program over an active mining phase. The drill and blast technical group was responsible for creating blast patterns to reduce spillover between these phases. Unrealistic goals and expectations were initially set for the area of the pit. The drill and blast technical group needed to figure blast objectives and work with the geotechnical team to align with these goals. This paper will go over the executed example of setting up spillover targets and expectations for multiple sections of an operating mine. Different sections of the pit had different control measures and blast objectives due to narrow laybacks and double benching. The use and value of blast objectives and goals were beneficial in setting expectations and measuring design success. Having unrealistic blast goals can set up the operations to fail or get frustrated in trying to work on an impossible task. The problems and risks of phase interactions for many open pit operations need to be considered in the design process, along with designed controls that minimize the probability of any safety incident. Mine designs are being created in the industry and do not consider phase-to-phase mining interaction and the impact it would have on safety or production. The best future for safer mines is blast patterns that reduce spillover between phases of mining and pit designs that might account for spillover interaction.

Jan 1, 2024

By Qian Li, Li-chen Hou, Yong-bin Yang, Tao Jiang, Jian-jun Hu, Bing Xu

Extraction of gold from refractory gold concentrates usually requires an oxidation step to remove arsenides、sulphides and carbonaceous matter. In this investigation, the gold concentrates were two-stage roasted under different atmospheres and temperatures. Results indicated that at the first stage, under neutral atmosphere, the removal rate of arsenic increases as the temperature rises. Under the oxidizing atmosphere, with the increase of temperature, arsenic content in the residued calcine increases, in addition, the volatilization of arsenic is also affected by the oxidation of carbon that generated CO, which is advantageous to the decomposition of arsenate decomposition. At the second stage of roasting, it is the higher temperature and stronger oxidizing atmosphere, the faster sulfur and carbon oxidated rate is, but at the same time, the calcine appears the phenomenon of consolidation because of the phase of silicate compounds generate.

Jan 1, 2015