Search Documents

By Remo Grandori

"INTRODUCTIONDouble Shield TBMs were introduced in the market in the early seventies with three main targets:• Increase the TBM performances in term of advance per day thanks to the ability to erect a segmental lining simultaneously with the excavation phase.• Be able to advance through unstable and disturbed rocks under the protection of the shields• Provide a finished tunnel by installing a precast lining as the TBM advance.In 2003 SELI developed the design of the Double Shield Universal (DSU) TBM as an evolution of the original Double Shield TBM design.This new TBM design was targeted to improve: the TBM capability to advance through squeezing/converging rock formations under high cover, the telescopic joint design (allowing by such to operate the machine in double shield mode in very weak rock), the capability of the TBM to investigate and treat the ground around and ahead of the tunnel face.In the same lapse of time Single Shield TBMs, originally utilized for soft ground tunnelling, extended progressively their range of application to mix rocks and finally to hard rock tunnelling with increasing performances.This also thanks to the substantial reduction in the installation time of the segmental lining ring that contributed to minimize the TBM stand by time between two consecutive boring strokes.Today the choice between the two types of TBMs needs to be carefully evaluated project by project since one type of TBM may “prevail” in certain geologies and diameters and vice versa.THE VISHNUGAD PIPALKOTI TUNNELThe Vishnugad Pipalkoti Tunnel is part of the 444 MW Vishnugad Pipalkoti Hydro Electric Project (VPHEP) on Alaknanda river in Uttarakhand (India).The Owner is the Indian electric company “Tehry Hydro Development Corporation” (THDC) and the World Bank finances the project.The Headrace Tunnel total length is 13.4 Km and a section of about 12,3km will be excavated by TBM by SELI Overseas (Italy) in subcontract to HCC (India) the General Contractor for the project. The TBM will be delivered ex workshop in March 2016 and it is foreseen to start boring in the second half of 2016.Figure 1 below shows the location of the project and the following Table 1 summarizes the geometrical characteristics of the TBM tunnel."

Jan 1, 2016

By E. P. Youngman

A new mining law for the Recublic of Polend was promulgated by presiden- tial decree dated November 29, 1930, published in the Journal of Lews (Dzienni stex) No. E, text 654, December E, 1530, and wes to become effective January 1, 1932, in all Polend except Silesie. Its adoption in Silesia wes dependent pon the action of the Silesian Diet. As the new law is considered an im- provement over the old Austrian Mining Lew, which is operative in the Silesian districts of Bielsk and Cieszyn, and the Prussian Kining Law, which is opera- tive in Upper Silesia, no delay in its adoption for Silesin was looked for. This new law codifies the various juridical regulations pertaining to ines existing in different parts of the Polish Republic but does not include legislation with respect to the extraction of minerel oil, especially crude oil. Petroleum legislation was postponed to a later date in order to facili- tate codification in other fields. Koreover, as the oil industry exists in Galicia elone, deley will not be detrimental.

May 1, 1932

By O. C. Ralston

The Bureau of Mines has under development on a technical scale an electrolytic process for treating oxidized ores of zinc , using caustic soda as an electrolyte . Whereas the Bureau process can alternately make either solid zinc or zinc dust , the following paper , from the Ludwigshafen research laboratory of the well -known I. G. Farbenindustrie , A. G. , of Germany, deals only with production of zinc dust from sodium zincate solutions and may well serve as introduction to the subject for American metallurgists . The Bureau of Mines pioneered in the idea ; a study on laboratory scale by H. J. Morgan and 0. C. Ralston was made early in the First World War, and published in Transactions of the American Electrochemical Society . The Eckardt paper , translation of which follows , goes more thoroughly into the preparation of electrolytic zinc dust , and later publications of the Bureau of Mines will deal with broader details and application of the idea to treatment of lowgrade ores and metallurgical intermediates , which is the point where Eckardt left off . 4 The Eckardt report became available through operations of Field Information Agency , Technical ( FIAT ) of the Office of Military Government for Germany (US ) , which made bibliofilm copies of the files of internal technical reports of many of the German industrial establishments , Eckardt's report is dated April 1939 and was taken on FIAT Microfilm Reel MM 106 , frames 82-101 , which is on file as Publication Board Document 41411 in Office of Technical Services of the U. S. Department of Commerce , Washington , D, C , Eckardt points out that the normal source of zinc dust is the blue powder of the zinc retorts , which decreases in volume every year owing to technologic improvements in zinc smelting. I. G. saw the importance of making a

May 1, 1948

By Jiang Feng, Zhang Libo, Peng Jinhui, Guo Zhanyong, Ju Shaohua, Lei Ting

The basics of microwave drying process of CuCl residue were studied by comparing the dielectric property of the residue with different moisture contents. The dielectric properties were measured by microwave cavity perturbation method. The dielectric constant and dielectric loss factor of the CuCl residue have a linear correlation with the moisture content. With this relationship, we can realize on-line measurement of moisture content of the CuCl residue by dielectric properties. The microwave drying experiments with different thicknesses (1-5cm) of CuCl residue were carried out, and the heating curve of the materials under different microwave powers (250-450W) was made. From these parameters, an optimized operation parameter of microwave roasting technology, the thickness of CuCl residue filter cake to be microwave roasted should be 2cm , was deduced.

Jan 1, 2015

EDITORIAL comments on the anthracite report of the Federal Fact-finding Coal Commission, which became public on July 5, together with an analysis of its more important conclusions, will be found on another page of this issue. In this place, only a few extracts from the report, bearing more directly on technical matters, can be quoted, for lack of space. COST OF MINING Mining cost, as it stands on the books of each mining company, represents the average cost of the total output, all sizes, of anthracite. Egg coal has at least five times the market value of barley, but these' sizes are mined together and their costs can not be separated. Mine costs directly reflect the conditions under which these deposits of coal are recovered. Even within the few counties in which anthracite is found there is a conspicuous range of natural conditions. The distinc-tion between the Northern, Middle, and Southern field, or, as they are also termed, the Wyoming, Lehigh, and Schuykill regions, is primarily geologic and topo-graphic, but the effects of the natural conditions largely control costs. The contrast is great between Some of the level-lying beds of moderate but fairly constant thickness under the broad Wyoming Valley, where mining and underground haulage present relatively simple problems to the engineer, and the steeply pitching or overturned and faulted beds of variable thickness in the Schuykill field, where crushed coal' and treacherous roof multiply the difficulties of mining; and increase the unavoidable waste. Even more direct is the connection between geologic processes and the, differences in the character of the coal as mined, the varying proportions of large and small sizes demanding differences in preparation and resulting in different average prices realized for the product of the mines.

Jan 8, 1923

By Dion Weatherley, Raúl Castro, Pablo Cid, René Gómez

In underground mining, hang-ups due to coarse fragmentation are frequently observed in drawpoints, drawbells, and ore passes during ore draw. Hang-ups can often require operational interference and hang-up removal activities. Drawpoint and drawbell design has been shown in some studies to influence hang-ups; however, the full extent of this influence remains open to question. In this study, the discrete element method was used to analyze the effect of hang-ups on three distinct drawbell geometries: the Drawer type, Circular type, and El Teniente type. The drawer type was used as the base case given that data was available from a physical model in which hang-ups were studied. The drawer type base case data was then used to calibrate our numerical model. Results show that the El Teniente drawbell geometry sustained 13% more hang-up events as compared with the base case, while the circular drawbell geometry had 16% fewer hang-up events than the base case. From this study, it can be concluded that fewer hang-up events will occur with a rounded drawbell geometry.

Apr 11, 2023

By Zeyun Cai, Gaoyang Song, Bo Song, Yuhou Yang

In this research, super gravity field was introduced in the solidification process of high carbon steel. The experimental results show that the solidification structure of Fe–1 wt% C steel can be largely refined by applying super gravity at the cooling rate of 10 °C/min. Both the primary and secondary dendrite length was markedly reduced. In addition, the eutectic structure in the inter-dendrite was also refined with the obvious reduce of eutectic space. However, the macro-segregation of C along the direction of super gravity was caused with higher weight percent at the upper area than that at the bottom of the sample. The mechanism of solidification structure refinement and the C macro-segregation of Fe–1 wt% C steel in super gravity field were also discussed in this paper.

Mar 1, 2017

By F. A. Rutledge

[An a part of the United States Department of the interior program for the development and use of Alaska raw materials, the Bureau of Mines is conducting an investigation of deposits of nonmetallic minerals accessible to the Alaska Railroad for use in building; materials is In the Alaska Railroad-belt area. The results of the investigations, to date, indices that raw materials for the preduction of brick products are in plentiful supply as cloy in the Anchorage area, as fire clay at Sheep Mountain, and as shale in the Healy Creek coal formations near Healy, Alaska.]

Jan 1, 1953

By Joseph L. Jordan

Coal is essential to America?s future energy needs. To meet these needs mining methods must be safe, economical, and environmentally acceptable. Belt conveyor systems for coal haulage from surface mines offer great potential in this situation. The advantages over conventional truck haulage are particularly promising for area strip mines in western coal fields such as the Powder River Basin where relatively thick, flat-lying coal seams occur. The current demand for low-sulfur coal specifically emphasizes the need for better mining methods in these areas. Underspoil haulage is the term applied to transportation of coal from the pit to the surfate in area strip coal mines by belt conveyors in tunnels under the spoil. The advantages over trucks include lower manpower requirements, greater pit safety and efficiency, and improved reclamation procedure. This evaluation includes a comparison of total mining costs for truck haulage versus six variations of the underspoil haulage concept. The more efficient of these underspoil haulage systems have economic advantages over truck haulage which become more pronounced with deeper overburden, thicker coal, and higher annual production.

Jan 1, 1977

VOLUME III The objective of Volume III of this report is to provide a concise review of six major types of legal constraints, controls, and regulations on surface coal mining in the United States, as of January, 1976. At the same time, an attempt is made to format the details of federal and state exploration, mining, and reclamation regulations such that point-by-point comparisons can be made and updated as revisions occur. Thus, Volume III should provide both an executive overview and a user's manual of legal controls of surface coal mining.

Jan 1, 1976

By BUREAU OF MINES

TABLE OF CONTENTS

Sep 1, 1932

Any Australian who knows of the poverty of the early settlers in the first few years following the arrival of Captain Arthur Phillip with his "first fleet" at Botany Bay must feel proud of the progress that has been made in the 174 years that have elapsed since that momentous occasionGFor all its attractive appearance as reported by Captain Cook and Sir Joseph Banks, the shores of Botany Bay and of Port Jackson proved most ,inhospitable, and the accessible country surrounding them anything but suitable for sustaining the life of the small settlement. It is well known that during the first 15 or 20 years the hardy colonists and un-tfortunate convicts were close to starvation on several occasions and were only saved by the arrival of supply ships, which were dependent on the vagaries of wind and current, and the hazards of the uncharted seas they had to -navigate-.When Australia was little more than a miserable penal settlement, Great Britain was one of the great-powers of the world, and the U,.S.A. was an independent nation with a growing degree of prosperity that even then gave promise of its mighty awakening to become, as it has, a e.olossus of industry and commerce,-and the. leader in living standards of the world to-day.Australia, from such a shaky, and comparatively recent start, has risen to a position in which its living standards rank very high in comparison with those of most of the nations of Europe and America. Exact com-parisons are hard to fix because of the wide variety of factors involved .but the Institute of Pab?Lic Affairs .(Victoria) places Australia fifthin the world, excelled only by the U.S.A., Canada, Sweden and Switzerland. The next best after Australia are the United Kingdom, West Germany and France.How we achieved such a high standard of living is a vast subject for study but some of the economic aspects of our climb from abject poverty to a position of near affluence can readily be identified.

Jan 1, 1962

By J E. Everett

An essential requirement of product quality control in the mining industry is to be able to reliably predict key quality properties of finished product from the data available before the extraction of the ore. From a production viewpoint, the unit of data collection is generally the input and output data set for each shift of crusher production, but could be any period where mine precrusher data can be reliably matched with product data.This paper demonstrates that linear regression models can be used to predict crush grades from blast grades, even where the crush material is blended from multiple sources or pits for each of which differing regression models might apply. The advantage of using increasingly complex regressions models to match the available data to give increasingly more powerful models is examined. The best model for any application will be a balance between required predictability, available data and the business’ tolerance for complex models.The regression modelling approach has several advantages over the more classic method of run-of-mine (ROM) crusher trials, which will be discussed.The models can use any predictor variable such as grade, geotype and in situ density provided the preextraction data set can be reliably matched with post-crusher data and is significant as a predictor. The models have been used extensively in the generation of the daily crusher plan with the aim of maintaining finished product grade. This approach has also been used associated with exploration drilling and long-term planning.It is acknowledged that there are inherent problems in fitting lump and fines grade to a linear model. However, these problems are minor when they are used for interpolation within the window spanned by the shift blend records used to produce the model. This paper discusses some of the issues limiting linear regression models in this application, and suggests methods enabling consistent models to be formulated

Sep 5, 2011

By J. Hedderson, J. Starkey, S. Reeves, B. Hilscher

"As ore sorting becomes more common, it is important to quantify its impact on comminution circuits in order to precisely predict its effect on throughput, grind, and mill operating conditions. Since sulphides and other valuable minerals are often softer then the surrounding waste rock, the ore kept by a sorting system is typically softer than the average ore. In order to accurately forecast production, new measurements of hardness need to be performed on the new concentrated mill feed. This paper proposes a methodology to examine this effect quantitatively at an early stage of project development using the SAGDesign test.INTRODUCTION The application of ore sorting in the mining industry is one of the most promising recent technologies with the potential to cause step change in the way concentrators are designed. Most typically, ore sorters are used to sort a given ore flow for grade, either to reject waste from the mill feed, or rescue ore from the waste pile. Ore sorting technologies have been successfully applied at many mining properties in various forms and while the technology has reached or is reaching maturity in other industries, it is still in development in the mining sector. As a result, there is not yet a general consensus on the considerations that need to be made when designing a plant with ore sorting from a feasibility level above and beyond what is commonly performed as best practice. This paper will discuss those considerations and propose a methodology for integrating ore sorting into a comminution circuit at the design phase. Due to the linearly additive nature of the SAGDesign Test results, a “hardness balance” can be developed to estimate the ore hardness which would be measured in any sorting mass split using only two data points. This will allow a design engineer to make more informed decisions as to the most appropriate mass split to select in relation to the incurred operating costs and grinding circuit sizing."

Jan 1, 2019

By R. C. Weed

LEACHING in place at Cananea began in the 1920's on a limited scale. The first plants were small wooden boxes located underground in the Capote and Oversight mines, and output was low. Scrap iron was used as precipitant. Later several other small plants were started up. Leaching was limited entirely to underground areas, and production remained low. The Veta precipitating plant, the first on a larger scale, was put into operation in the late 1920's. After a period of intermittent service it was rebuilt in 1946 and has since been running continuously. In 1943 work on the Colorada open pit was started. This produced 40 million tons of waste, which averaged 0.20 pct capper. When these dumps had aged a few years it was decided to leach them on a large scale, and after considerable research and investigation a leaching system of pumps and pipelines was laid out and installed. At the same time the Ron-quillo precipitation plant was built to treat the copper solutions from the pit dumps. This plant started operation in March 1953. Leaching areas consist of the Colorada pit dumps and various mined out and caved underground stopes. The principal mineral, chalcocite, leaches readily in a weak sulfuric acid solution containing ferric iron. Enough pyrite is contained in the areas to produce an acid-ferric iron solution strong enough to dissolve the copper. Each area is studied to determine the best method of distributing the water over it and the best method of collecting the copper-bearing solutions after leaching has taken place. Water is generally distributed by means of ponds, ditches, and sprays. Spraying has proved the best method of spreading the water evenly; however, in a dry climate some water is lost through evaporation. After passing through the leachable material the solution is collected underground by dams and bulkheads and on surface by dams. An effort is made to give the maximum storage capacity practicable.

Jan 1, 1957

By William Gleason

The Society for Mining Metallurgy and Exploration (SME) has a long and proud history of being the world?s leading resource for the dissemination for technical information regarding the fields of mining and mineral extraction and processing. That reputation was met, and maybe even exceeded, with the programming for the Society?s 2014 Annual Meeting in Salt Lake City, UT Feb. 23-26. The meeting drew more than 6,700 attendees to the three-day conference that featured more than 90 technical sessions with 670 presentations. These sessions covered the breadth of the mining and minerals industry, but it was the so-called ?softer issues? that were discussed in the keynote session that kicked off the meeting. The keynote session, ?Community Engagement: Building Partnerships for Mining,? brought together some of the leading voices from the mining industry, as well as some of the top voices from nongovernmental organizations (NGOs) that work in the mining sector. The common ground between the panelists was their dedication to working to ensure a social, economic and environmental balance in the development of mines. ?We wanted to bring these NGOs in to begin a dialogue to see how we can work together,? said SME President Jessica Kogel. ?This is a space that SME has not typically operated in, but one in which SME can bring a technical, scientific voice to the discussion. SME wants to play a leadership role in creating partnerships between the technical, social and economic areas that are crucial to the success of any mining project.? In today?s environment, finding mineral deposits and extracting the minerals in an economically viable manner is just one piece of an increasingly complex puzzle. Earning and maintaining a social license to operate requires careful consideration of local and global impacts. The industry often comes under intense scrutiny when a new project is proposed and, therefore, it must strive to meet the highest ethical and environmental standards. Success requires cooperation and collaboration between the industry, community and NGOs.

By Y. Wang

Wet magnetic separation methods for recovering hematite and chromite fines and ultrafines are investigated in this paper. These methods include wet high intensity and high gradient magnetic separations, carrier or "piggy-back" magnetic method, magnetic field-induced aggregation and magnetic seeding. This investigation indicates that wet magnetic separation is more efficient for fines and ultrafines whereas other methods can be used to enhance the particle aggregation and/or the magnetic response. The magnetic behaviour of these minerals with respect to magnetizing field, particle size and temperature is also presented.

Jan 1, 1993

By George T. Faust

The petrographic microscope plays an important role in the mineral dressing of nonmetallic materials. Petrographers and mineral technologists have evinced an interest in the technique developed, specifically, for mineral-dressing problems. The following dissertation makes the informa¬tion more generally available. ACKNOWLEDGMENTS The authors are indebted to O. C. Ralston, chief engineer, Nonmetals Division, and to Will H. Coghill, supervising engineer of the Southern Experiment Station for a critical reading of the manuscript. They are also indebted to their colleagues for technical information obtained in the course of cooperative work, in particular to J. B. Clemmer for the use of the data on fluorite.

Jan 1, 1940

By A Giblett, B Putland

This paper provides a simple guiding framework for grinding circuit optimisation, focussing on common themes in past optimisation success stories, the conditions for success and techniques that can be employed to identify and define opportunities. Many significant grinding circuit improvements have been reported for operating plants, based on recurring themes such as the optimisation of mill feed size, mill liner design, process control, critical size, grinding media and classification. The paper condenses these experiences into a set of simple questions for the operator to ask, and provides guidance towards identifying and achieving the optimisation goals.CITATION:Giblett, A and Putland, B, 2018. The basics of grinding circuit optimisation, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 129–140 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By Francis C. Furman

Microscopic evidence indicates that the high sinterability of certain commercial dolomites is tied to specific dolomite textural characteristics. This study encompasses detailed characterization of the unprocessed dolomite and sintering doloma results. The chemical and mineralogical compositions, insoluble residue, chemistry homogeneity, crystal size, primary carbonate texture, secondary dolomite texture, deformation structure, porosity type, porosity, and density of the raw dolomite were observed. These characteristics are compared with sintering trials of <74um powder-compacts samples in which holding times were varied. The evolution of the dolomite characteristics are reviewed and related to the final sintered doloma characteristics. The critical characteristics of a single-stage sintering brick dolomite are the following: 1) primary oolitic texture, 2) dolomite purity, 3) dolomite stoichiometry 4) minimal impurities, less than 1 weight {%} Fe2O3 Al2O3 and SiO2, 5) chemical homogeneity, 6) high density, 7) very low porosity, S) very coarse homogeneous crystallinity, 9) nonplanar dolomite texture, 10) abundant strain related slip microdeformation structures, 11) minimal subsequent alteration. Even with grinding to <74um the nonplanar dolomite texture and slip deformation still have a major effect on doloma sintered density. The three newly identified characteristics of single-stage sintered refractory brick dolomite are their primary oolitic texture, secondary nonplanar texture and abundance of stress related microdeformation structures. The primary oolitic texture reflects a homogeneous pure carbonate with respect to chemistry and crystal size secondary nonplanar texture produces crystals with large surface area to volume ratio. Stress related slip deformation moves CO, groups in to the same site of another CO, group but different orientation which is very unstable. All of these characteristics may facilitate the formation of higher density dolorna sinters.

Jan 1, 1995