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By L. Vinnett, J. Yianatos, S. Flores

"A numerical conditioning analysis for mineral recovery estimation was performed for industrial flotation plants, considering the copper (Cu), molybdenum (Mo) and iron (Fe) separability. A modified relative condition number, ?, was presented that allowed sensitivity analysis to be evaluated for the component recovery by means of an analytical formula. This closed form made it possible for the error propagation to be determined from feed, concentrate and tail grades with different orders of magnitude. The ? parameter can be evaluated using available grade data from the design criteria or historical mass balances, in which the variability is typically unknown. Reconciled data from different Cu/Mo concentrators were employed to evaluate the effect of small numerical disturbances in the grade data on the mineral recovery estimation. Higher error propagation was typically observed for Fe. The Mo minerals presented numerical problems, mainly in second cleaners and in the first cell of rougher banks. Lower condition numbers were observed for Cu due to the higher flotation rates.Mass-balance data reconciliation without redundancy was evaluated for a typical Cu/Mo flotation circuit using relative error minimization. Significant relative errors in the mineral recovery estimation were obtained with nonreconciled data in ill-conditioned problems. Negligible improvements in the mineral recovery estimation because of the data reconciliation with regard to the nonreconciled approach were obtained in well-conditioned problems. In addition, the improvements in mineral recovery estimation by using Cu, Mo and Fe in the data reconciliation were nonsignificant with respect to using only the best-conditioned component in well- and ill-conditioned problems.Despite the effort in data reconciliation and data repetition, poor performance may be obtained in ill-conditioned problems, which can deteriorate the flotation rate characterization. The error propagation has a negative impact on the mineral recovery of the first cell, which may significantly bias the flotation rate characterization of both valuable and nonvaluable elements.IntroductionMass balances have been extensively used in flotation processes to determine the mass flowrates (production) and mineral recovery (efficiency) of valuable minerals. Simple relationships for steadystate processes based on the feed, concentrate and tail grades can be obtained by taking a black-box approach. However, the calculation of concentrate flowrates from different components of the system, such as size fractions, chemical elements or minerals, does not satisfy the mass-conservation principle because of measurement errors (Smith and Ichiyen, 1973; Romagnoli and Sánchez, 2000). Mass-balance data reconciliation allows for obtaining a unique solution that satisfies the total and component mass balances, making small adjustments to the process data and taking advantage of the information redundancy (Narasimhan and Jordache, 2000). This methodology, which is based on a constrained weighted least-squares minimization, has proved to be robust when measurement errors are normally distributed, in the absence of gross errors.Commercial software has been developed to conduct massbalance data reconciliation in flotation processes, including MATBAL (Algosys, 2002), BILMAT (Algosys, 2013), JKMultibal (JKTech, 2013), BILCO (Caspeo, 2013) and HSC Chemistry (Outotec, 2013), which accomplish the reconciliation using known data accuracy in the optimization problem. The data accuracy can be obtained by sampling a stream n times in a run, known as repeats, each with independent chemical assays. Some unmeasured variables can be estimated using the measuring redundancy and sensor location. At present, grade and flow rate sensors may be incorporated in flotation to conduct real-time mass balances. However, a lack of sensor calibration and maintenance for suitable online measurements hinders the quality of the information. In"

Jan 1, 2016

By R. K. Mishra, A. Kula, X. Jia, M. Niewczas

The mechanical properties of Mg-Gd and Mg-Y solid solutions have been studied under uniaxial tension and compression between 4K and 298K. The results reveal that Mg-Gd alloys exhibit higher strength and ductility under tension and compression attributed to the more effective solid solution strengthening effect and grain boundary strengthening. Profuse twinning has been observed under compression, resulting in a material texture with strong dominance of basal component parallel to compression axis. Under tension, twining is less active and the texture evolution is affected mostly by slip. The alloys exhibit pronounced yield stress asymmetry and significantly different work-hardening behaviour under tension and compression. Increasing of Gd and/or Y concentration leads to the reduction of the tension-compression asymmetry due to the weakening of the recrystallization texture and more balanced twinning and slip activity during plastic deformation. The results suggest that under compression of Mg-Y alloys slip is more active than twinning in comparison to Mg-Gd alloys.

Jan 1, 2015

By JIACHENG XIE, XUEWEN WANG, QINGBAO BAO, ZEWEN YAN

The general application of memory cutting technology to shearers is improving the intelligence of the working face, but it has its limitations. It is only suitable for conditions where the environment of coal seam is changing slowly. It compensates for the cutting height by changing the fuselage attitude, and frequently adjusts the height to control the learning cutting trajectory, but due to the problems of shearer control and height adjustment accuracy, it cannot adapt to and compensate for the change of cutting height in a timely manner, resulting in poor cutting accuracy. This study puts forward a virtual memory cutting method based on prediction of the shape of the armored face conveyor (AFC). The integrated key technologies include generation of virtual teaching cutting curve, height adjustment strategy of front and rear drums, cutting

By Williams K. C

This paper presents a brief account of the plant which has been developed at Port Pirie to recover, by vacuum distillation, the greater part of the zinc content of desilverized lead. The present plant is an experimental unit, which is run in conjunction with the normal refinery practice, but can be cut out of the circuit. It will shortly be dismantled and duplicate units will be built on the sites chosen for the final plant installation.The unit described here has treated flows of 16 to 37 tons per hour of desilverized lead, to recover 90 to 95 per cent of the zinc contained in it. It is not intended here to detail all aspects of the vacuum dezincing operation, nor the developments which precededthe adoption of this design. The essential features of the present plant will be described and, where these are peculiar to the present experimental location, the intended alteration for the final plant will also be mentioned. OUTLINE OF PLANT AND PROCESSLead issues from the continuous desilverizing kettle at about 350° C. containing about 0·57 per cent Zn. It is conveyed by a tiled launder to the preheater, where it is heated to 580-620° C.Hot lead from the preheater enters the vacuum vessel via a barometric leg. From a reservoir holding about 19 tons of lead it falls by gravity in a thin film exposed to high vacuum (20-50 microns)3 and leaves the vessel via a barometric leg, entering the lead pot. The lead leaves this pot at 540-560° C., containing 0·03 to 0·06 per cent Zn, which is removed, together with residual antimony of 0.02 to 0·06 per cent, by a separate final refining process.

Jan 1, 1956

By J. J. Gusek

The Riley Pass strip mine is an abandoned uranium-bearing lignite deposit in Harding County, South Dakota, covering about 150 acres of highwalls, pit floor and mine spoils exhibiting elevated levels of radioactivity. Six reclamation design alternatives were developed, ranging from doing nothing to reclaiming to approximate original con-tour. The alternatives were evaluated for expense, site stabilization, and mitigation of public safety hazards. A comparative economic evaluation on three of the alternatives was completed for the Forest Service in selecting an alternative and substantiating federal funding requests. This evaluation included economic impacts associated with physical and radiologic health hazards, affects on recreational users, socioeconomic impacts and environmental improvement.

Jan 1, 1995

By A Dunne, R Kruger, H Coleman, P G. Laurens

External and internal challenges in mining are increasing the difficulty and complexity of operating mines. The external mining environment has a big impact on mining operations and is driving the focus on safety, sustainable mining, green issues, profitability and productivity. There is a very high emphasis on ‘reducing cost to improve’, lower mining and beneficiation costs by eliminating waste/inefficiencies (reduce people, use less consumables, multiskilling, etc). The internal mining environment is getting tougher to operate in, with the deposits being more difficult to mine, more difficult to manage due to external pressure along with issues associated with maintaining quality, etc.Technological and environmental developments too numerous to mention, mean that cost control models, reduction in human resource numbers, as well as other drastic measures to curtail expenditure and increase profitability have become part of everyday business. The capability to manage the mining environment in a systemic manner has been lacking and this increases the pressure for performance on those individuals operating and managing mines.Working smarter has become crucial to ensure that businesses optimise the use of their resources, become more safety conscious, more productive and remain cost-effective, while recognising the importance of sustainable mining now and in the future. The logic of determining and managing to the capability of the mining value chain will be examined and the underlying assumptions or beliefs guiding behaviour and decision-making will be highlighted.In order to identify the obstacles in the mining value chain that hinder achievement of its full potential, the following questions have to be asked:What are the factors that influence the performance of a mining value chain?What is the design capacity of the mine?How can the inherent flow and value capacity of a mine be determined?What types of solutions will allow a mine to operate at its inherent flow and value capacity?This article will discuss the way we plan, measure, assess and manage the mine value chain, by addressing the following factors:balanced capacity versus flow and value capacity designthe use of averagingoptimising individual components in a value chain versus optimising the whole value chain.Optimising flow and value through the mining value chain is one of the three pillars of Mineral Resource Throughput Management (MR™). MR™ is an entrenched and academically supported philosophy that has been successfully applied in the past decade in various mines throughout the world by EXXPLEO, a mining and beneficiation consulting company. EXXPLEO has partnered with HCL (a global IT company) to embed the MR™ philosophy, methodology and toolsets into a formal software product called Synchronised Digital Mining (SDM). The SDM system will provide mining companies with a sustainable platform to effectively apply the MR™ principles and toolsets effectively across all operations targeting increased productivity, efficiency and profitability without having to train operations and management staff into expert MR™ practitioners to successfully achieve the desired results.CITATION:Dunne, A, Laurens, P G, Kruger, R and Coleman, H, 2015. Optimising flow in the mining value chain, in Proceedings Iron Ore 2015, pp 437–442 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By Howard A. Perko

Soldier pile and lagging is a conventional means of temporary excavation shoring. Timber lagging design has traditionally been based upon the designer's experience or empirical rules. One such method is the Goldberg Zoino chart used by the Federal Highway Administration. Most of these methods restrict the designer to a consistent soil profile, certain pile spacing, construction grade timber lagging, and limited depth. The methods do not take into account surcharge loads or a variety of other factors that could arise. A designer working outside of ordinary circumstances with unusual loads, varying soil conditions, or alternate lagging materials has difficulty estimating lateral earth pressures. In rigid earth retention systems, lateral earth pressure is generally assumed to be constant along the length of the wall. In soldier pile and lagging systems, the lagging is often considerably less stiff than the steel soldier piles. As the lagging deflects, the soil tends to bridge between the stiffer elements resulting in a lower pressure on the lagging. Several previously published methods by others for determining this reduced pressure are summarized and discussed. These methods typically consist of using a portion of the active earth pressure in several different pressure distributions. A simple theoretical model is presented for determination of lateral earth pressures on wood lagging. The model is based on a three-dimensional "silo" shaped sliding wedge analysis. Results of the model are compared with other published methods. The model compares well with these methods which cover the normal spectrum of design situations. In addition, the model can be used to estimate lateral earth pressures outside typical situations.

Jan 1, 2008

[This Report represents the culmination of work perfomed under Contract No. .,JG1551A8 for the U.S. Bureau of Mine.The &apos;.:o-< embeded a site evaluation, engineering E:-y- ,, esign, and preparation of specifications for construction of a Transport Research 7 :4 (HTRF)The HTRF is designed as a research facility J evaluate the hydraulic transport of large lump coal at a prototype ;e scale. The HTRF is to be constructed and operated by the Pittsburgh and Safety Research Center of ;. re U.-AN a*, their Bruceton, Pennsylvania test center. In terms of technical capability, the HTRF will have transport pipeline:: of -, twelve-, and eighteen-inch diameter _&apos; with supporting coal handling n , water forage a.^ &apos;d conveyance, mixing, pumping, and dewatering equipment, plus instrumentation and controls. Maximum design velocity 13 20 ft/sec.; solids concentration, by, volume, will; 1 be a maximum-- of sixty, percent. Each test loop is designed to accommodate solids of up to one-third the diameter e - of the pine. The Final Report Pr.-&apos;I-rents information of t HTHF,. including the site evaluation, design criteria, a description of the a description of the procedure to be used for operation of the facility, an estimate of the cost to construct the f^Cilit:r, 1 p el_~lli.&apos;iU construe`, icn Schedule, and a construction suicJ_iicaT.l_ccn&apos;. T e c011SLr?Jc&apos;.ion soecl_ i.on _ccnta_i:s technic.&apos;..i re7,uir: (-n`,s for !&apos;urr1S~ &apos;~latcr..al. and ec-uipr,ent for :":C1 C_`:_C ti on of ti,_ H ice&apos; u:&apos;.:i ._II u s(-.6 for ~.Iir: .3!7 soliciting bids. `.l_o included n cc&apos;;,art_- c?r~.air sV:et..: :s ^nd rr^.?]

Jan 1, 1976

By M. G. Fleming, F. Warner, R. W. Boswell, M. J. Cahalan

The annual dinner of the Institution was held at the Savoy Hotel, London W.C.2, on 22 April, 1971. The President, Mr. M. J. Cahalan, was in the Chair; members and guests numbered 320. The toasts of The Queen and Queen Elizabeth The Queen Mother, Prince Philip The Duke of Edinburgh, The Prince of Wales, and the other Members of the Royal Family were proposed and loyally honoured. R.W. Boswell proposed the toast of the Institution of Mining and Metallurgy, the president responded, Professor M.G. Fleming proposed the toast of the guests and Sir Frederick Warner replied

Dec 1, 1971

Unfortunate occurrences resulting in injuries, loss of life, and destruction of property by explosion, fire, and other mishaps during shaft sinking focused the attention of the Bureau of Mines on the need for safety standards For such operations. Information Circular 7810 was published to meet that need. The current revision updates and replaces IC 7810. Several States have some rules and regulations applicable to local conditions, and several Bureau publications (including some now out of print) cover the hazards that may be encountered in shaft sinking. Certain requirements of the Federal Mine Safety Code and Federal Coal Mine Safety Act may be applied, but there are no definite, uniform standards that will guide those desiring to sink a shaft safely and bring about uniform safety inspections.

Jan 1, 1968

By J. Douglas Causey

In 1987, at the request of the Bureau of Land Management, the U.S. Bureau of Mines studied a part of the 21,296-acre Million Hills Wilderness Study Area (NV-050-233) in order to evaluate its identified mineral resources. The study area is located in Clark County, NV, about 46 miles south of Mesquite, NV. The area is on the east edge of the Gold Butte mining district and has had minor production of copper and zinc from the Azure Ridge mine in the early 1900&apos;s. Assessment work was being done on the Esperanta claims, which covers the mine workings, in March 1987.

Jan 1, 1988

With the dawning of a new century came the beginning of a new era in the coal industry. Instead of the traditional practice of only buying and selling produced coal in the United States, a coal futures market was established. The New York Mercantile Exchange began trading coal futures in July 2001. But, even in this new era, many of the old is-sues that have beset the coal industry still remain, as was evident in2001. Coal production increased to are cord level during 2001, according to preliminary data from the US Energy Information Administration(EIA). Production in 2001 rose by4% to 1.01 Gt (1.12 billion st), compared with 2000 (Table 1). This barely surpassed the previous record level of 1 Gt (1.11 billion st)set in 1998. Coal consumption remained unchanged. The additional production was used to replenish the depleted stockpiles that had resulted after two years of declining coal production and increasing coal consumption.

Jan 1, 2002

By A. T. Adema

The cohesive zone, where the ore fed into the blast furnace softens and melts, is critical to the blast furnace performance and stability due to its influence on the gas and solid flow. This paper de-scribes a project for the development of a process model to predict the cohesive zone properties and the results of its first step; the solid flow model. The process model is expected to describe a realistic solid burden flow and the formation of the cohesive zone, its shape, location, structure, permeability, and in particular the mineralogical changes within the cohesive zone. This will be achieved using various simulation and computing tools: a combination of the Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD), the DEM?CFD hybrid approach, together with models for the thermodynamics and reaction kinetics. The key benefits of the hybrid approach lie in the coupling of the continuous phase and the discrete particles, and the possibility of introducing thermodynamics and reaction kinetics into the system in a more realistic manner. Two DEM simulations are presented for a small scale blast furnace to investigate the influence of non-spherical particles on the solid flow. This influence can be observed from a more even solid flow pattern and a reduced deadman size. The results indicate the requirement to include non- spherical particles in a blast furnace simulation to achieve a realistic solid flow.

Jan 1, 2014

By Games Slayter

NO reasonably well-informed person believes that the role of minerals, both metallic and nonmetallic, will be any less important in the future than it has been in the past. The contrary is true. Industrialization is based on mineral resources and man&apos;s ability to make use of them. A nation&apos;s standard of living, its political and military power, will continue to depend largely upon the extent to which it is industrialized-and minerals are the raw materials both of the machine and the power to run the machine. Minerals are also the raw materials of human health and stamina. The world&apos;s healthiest, most vigorous, and most long-lived peoples have always been those that have lived in regions of the globe where the earth is rich, and kept rich, in the phosphates and other minerals required for the production of the so-called growth foods. Only a small proportion of the land surface of the globe is suitable under any circumstances for large-scale production of these and other essential foods. As things stand, only a part of this land is capable of such production either because the soil minerals have been exhausted by cultivation, or because they never existed in the soil in sufficient quantities.

Jan 1, 1943

By W. H. Boyer, J. W. Gabelman

The concept of metal zoning has long been recognized (Spurr, 1907, 1923; Emmons, 1924, 1926; Lindgren, 1933; Rateman, 1950), although it has been considered indistinct for most epithermal districts. The geometric relation of barren zones of hydrother-mally altered rock to ore deposits was emphasized in the work of Lovering (1941, 1949, 1950), Sales and Meyer (1948, 1949, 19501, Burbank (1941, 1950), Schwartz (1939, 1950), and Kerr (1947). Lovering (op. cit.) and Sales and Meyer (op. cit.) emphasized the consistent presence of barren alteration envelopes enclosing individual ore bodies, particularly of the vein type. Schwartz (1950) noted a difference between the distribution of alteration zones described by Lovering and by Sales and Meyer, as compared with those associated with the porphyry copper deposits of the Southwest. The disseminated deposits of the Southwest usually occur within large bodies of altered rock whereas most veins do not. In the following discussion the mineralization process is conceived of consisting of two distinct phases: pre-ore nonmetallic alteration and metallization. In the present investigation the position, size, and shape of all known hydro thermally altered areas and the position, size, and metal type of all known ore deposits were plotted on base maps of southwestern and west-central Colorado (Figure 1). The maps indicate a generally consistent geometric relation between altered and metallized areas. The addition of alteration to the pattern of metal deposits establishes a temperature zoning pattern of much greater clarity than that formed by the epithermal metal deposits alone, and allows a more precise definition of mineral belts. The center of strongest mineralization is indicated to be the area of greatest barren alteration, and metal deposits are grouped about it both under structural control and crudely in response to temperature zoning. The combination of an area of strong alteration and associated marginal clusters of metal deposits is defined as a mineral district. The strong similarity in individual deposits, in groups of different types of deposits, and in the alteration-metallization relation in districts throughout the region implies that a single metallogenic province is represented in southwestern and west-central Colorado. The occurrence of deposits in Tertiary voi-canics indicates a late Tertiary metallogenic epoci., although an early Tertiary epoch is known locally as at Ouray. Patterns formed by mineral districts can be

Jan 1, 1961

By N M. Caira

The North Arm of Sulawesi hosts numerous gold and base metal occurrences. Compilation and analysis of geological, tectonic, geochemical and isotopic age date data collected over the past six years on the central part of this region have resulted in the definition of 184 prospects and mineral occurrences of various styles occurring in diverse geological settings representing varying tectonic environments and erosional levels. Mineralisation of the following styles have been recognised: porphyry Cu-Au; porphyry-related gold and base metal veins; high-sulphidation Cu-Au-As; low-sulphidation epithermal Au; hydrothermal breccias; and sediment-hosted Au mineralisation. Clusters of occurrences/prospects form mineralised districts representative of magmatic systems with characteristics determined by the tectonic environment prevailing during formation and the subsequent level of exposure by erosion. Distinctly different Miocene and Pliocene porphyry systems are now recognised whilst most of the remaining epithermal mineralisation is thought to be Pliocene or later. The central North Arm of Sulawesi is composed of a Miocene magmatic island arc that is built on an Early Tertiary basement of predominantly oceanic basaltic rocks and overprinted by a Pliocene magmatic arc. A structural fabric dominated by SSE arc-normal and ESE arc-parallel faults was established during the Miocene under a dextral wrench regime and intersections of these major fault sets are favoured sites for Miocene porphyry Cu-Au mineralisation. Strong dextral tension caused by the collision of the Sula Platform, at the close of the Miocene, led to arc-parallel rifting. Sinistral reactivation of the major Miocene structures in the Pliocene led to further rifting, and ENE-dilation. Pliocene intrusions and related mineralisation exploit these dilatant settings. Miocene porphyry Cu-Au mineralisation occurs where late-Miocene quartz diorite stocks have intruded the margins of earlier Miocene plutons of intermediate composition. Porphyry centres have associated peripheral base metal veins, and skarns. Overprinting of porphyry vein sets by epithermal veins is common. Sediment-hosted gold mineralisation occurs in calcareous sediments associated with the Miocene arc. Remnants of the Pliocene volcanic arc, comprised of dacite volcanics, intrusions and voluminous pyroclastics, dominate the south coast and host porphyry Cu-Au, high sulphidation Cu-Au-As deposits, low-sulphidation epithermal Au veins and disseminated gold mineralisation. In some prospects, mineralised sinters are preserved adjacent to vein systems and deeper mineralised stockworks. Diatremes are common and large caldera structures have been identified. Pliocene stocks and porphyry dyke swarms penetrate the main central and northern parts of the Miocene- arc introducing additional porphyry Cu-Au, base metal hydrothermal breccias and low-sulphidation gold veins. Rapid uplift and erosion has resulted in a highly variable preservation of styles of mineralisation adding further diversity within the mineralised districts and telescoping within deposits.

Jan 1, 1999

By S R. Pecover

AustraliaÆs opal and sapphire mining industry has fallen from its peak in the 1980s and 1990s into a significant low today. This is not due to exhaustion of the resource, but instead an over-reliance of the Australian miner on achieving a fair price for the gemstone product from offshore middlemen dealers. Gemstone and geological research is also at a low as Federal higher education expenditure has fallen with research institutions relying increasingly on private funding in an environment of restricted autonomy and flexibility for researchers. What little remaining research skills the universities have is being bled into the private sector as a result of the mining boom and encouraged by lower than average academic salaries. Nevertheless, some highly innovative research has been taking place, often by self-funded individuals and retired academics simply with a desire to advance the understanding of the particular branch of science in which they are interested. New models for the formation of sapphire and opal are now beginning to be applied to the exploration for these gemstone commodities. This research, together with well thought out plans for managing the gemstone product through its value-adding steps to the jewellery retail level, has the potential to bring about a resurgence in the Australian gemstone industry.

Jan 1, 2008

By A. Patri, D. S. Nimaje

Wireless sensor networks and wireless communication systems have become indispensable in underground mines. Wireless sensor networks are being used for better real-time data acquisition from ground monitoring devices, gas sensors, and mining equipment, whereas wireless communication systems are needed for locating and communicating with workers. Conventional methods like wireline communication have proved to be ineffective in the event of mine hazards such as roof falls, fires etc. Before implementation of any wireless system, the variable path loss indices for different workplaces should be determined. This helps in better signal reception and sensor node localization, and also improves the method by which miners carrying the wireless devices are tracked. This paper proposes a novel method for determining the parameters of a suitable radio propagation model, which is illustrated with the results of a practical experiment carried out in an underground coal mine in southern India. The path loss indices, along with other essential parameters for accurate localization, have been determined using the XBee modules and ZigBee protocol at 2.4 GHz frequency.

Jan 1, 2015

By P Craig, M Holden, C Zhang, D Foster, J Oh, S Saydam, J Liu, H L. Ramandi, S Akdag

High stress in rock masses can cause significant instability problems such as squeezing deformation in soft rock and rock bursts in hard rock. The support system applied in burst-prone areas in high-stress conditions is required to be able to carry high load and accommodate large deformation of the rock mass without experiencing any serious damage. Yielding support systems are promising to provide support for both squeezing and burst-prone rock mass encountered in mining or tunnelling at depth. They are ideally strong and stiff initially and then ductile after yielding (Potvin and Hadjigeorgiou, 2020). With respect to support design, a ground support system has to create a safe working environment under both static and dynamic loading conditions by providing the functions of reinforcing, retaining, holding and connecting elements (Cai and Kasier, 2018). Rigid rock bolts and cable bolts perform reinforcing and holding functions of a ground support system. In highly fractured ground or with large excavation spans (eg at roadway intersections or in caverns), unstable ground depth can exceed the length of typical rigid rock bolts (ie greater than ~3.0 m). In such cases, flexible cable bolts are needed to tie the reinforced and retained rock mass back to deeper and more stable rock. The flexibility of cable bolts allows anchor lengths greater than the tunnel opening that would otherwise restrict rigid bolts. Cable bolts also offer higher strength to weight ratio, with tensile strengths 2–3 times that of standard rebar bolts. This high strength comes at the cost of lower strain tolerance, typically around 5–7 per cent at break. Despite the lower strain tolerance, cable bolts are often used as dynamic support in demanding burst-prone ground conditions. The lower strain tolerance is compensated by allowing sufficient free length for stretching or incorporating a yielding device. There are a number of dynamic cable bolts available on the market and a number of testing campaigns have been undertaken to quantify the dynamic performance of these cable bolts. This paper reviews the existing range of dynamic cable bolts and discusses the potential areas for improvement and further research.

Nov 29, 2022

By Takashi Nakamura, Atsushi Iizuka, Yong Fan, Etsuro Shibata

The level of iron in typical copper slag reaches nearly 40% by mass, in the form of iron silicate. We designed a method to oxidize the nonmagnetic iron silicate to magnetite, permitting the selective recovery of the slag’s iron content by magnetic separation. This would effectively decrease the volume of dumped slag; the reclaimed iron could be used for iron and steel making. The crystallization behaviors of magnetite and hematite were studied as reaction products of the molten oxidation of copper slag. A gas atmosphere of 1% by volume of oxygen was found to effectively precipitate the slag’s iron content as magnetite.

Jan 1, 2015