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By O. F. Brown

The use of quality materials (aggregates and asphalt binder) in optimal proportions is the key to producing optimally performing hot mix asphalt (HMA). The Superpave mix design standard in the US introduced specific volumetric and binder property requirements in HMA design. Different methods for HMA constituent proportioning have been proposed in various guidelines. The design process to determine the HMA blend is currently iterative and engineers rely almost exclusively on experience. This approach is time consuming and often does not result in cost-optimal HMA mixtures. This paper introduces a mixed integer linear programming (MILP) optimization model for hot-mix asphalt constituent proportioning. The MILP model minimizes the total mix cost while satisfying all the volumetric, binder and mix property specification requirements. The model has been successfully validated with real-life example. The aggregates and binder ratios from the model were in close agreement with those from the contractor. The Bailey ratios and the gradation constraints were also satisfied. The cost of the optimal mix was $0.804/Mg less than that of the contractors?. This marginal reduction might make all the difference in an industry that is highly competitive. The MILP model also demonstrated that adding RAP to the contractor?s design would reduce the cost of the blend by $5.74/Mg. The virgin binder content was reduced by 1% because of the recycled asphalt contained in the RAP. This work represents the first successful attempt in incorporating both aggregate and asphalt performance requirements into the optimization formulation. Applying these models will ensure the minimum cost mix that meets all constraints and will increase profit margins for plant operators.

Jan 1, 2012

By K. Ding

The thermodynamic activity of MnO was measured in MnO-CaO-MgO-SiO2 slags that are typically encountered in the production of manganese-containing stainless steels. A gas equilibration-quenching technique was employed in measuring the activities. Activities of Mn in Pt-Mn alloys were redetermined at 1600ºC, which reconfirmed earlier results of strong negative deviations. MnO activities were then measured by equilibrating slags of various compositions based on a statistical experimental design procedure with Pt-Mn alloys under controlled partial pressure of oxygen in MnO saturated platinum crucibles at 1600ºC. Activities of MnO were found to increase with increasing concentration of MnO, basicity and CaO to MgO ratio. Two multi-coefficient regression models were developed to predict the activities and activity coefficients of MnO in slags at 1600ºC. Keywords: activity, MnO, slag

Jan 1, 2005

By Y. Duraisamy

This paper presents the compressibility of tropical peat reinforced with cylindrical cement column. When a cement column installed vertically in peat, its compressibility was reduced because of the hardened skeleton matrix formed by cement particles bonding with adjacent soil particles in the presence of pore water. The effects of diameter, number of columns and cement proportions in cement columns on the compressibility have been investigated in this study. The results indicated that compressibility index Cc and Ca decreased with the increase in diameter of the cement column. Specimens with 45 mm and 60 mm diameter of cement column were cured for 28 days, after which they were subjected to Rowe Cell Consolidation test. Based on the results obtained, it shows that cement columns can successfully reduce the compressibility of tropical peat.

Jan 1, 2007

By Mario Morin

The application of underground pre-concentration technology to narrow vein mining has the potential to change the entire economics of bulk mining methods when used in narrow vein situations. The rejection of waste at or near the face means that a higher-grade ore can be sent to surface. The waste rock can be reused directly as backfill. Swelling of the muck through blasting means that only 60 to 65% can be used as fill. Planning and scheduling of the fill usage is key to the success of this method. Through the use of simulation and system analysis, this paper examines the planning and scheduling implications of underground pre-concentration when applied to traditional narrow vein mining methods (cut-and-fill /drift-and-fill, longhole, AVOCA). It considers the logistical factors that represent potential system bottlenecks that are key to understanding the correct implementation and control strategies.

Oct 1, 2004

By Sanket Rawat, Ravi Kant Mittal, Vikash Prasad

"The understanding of the response of pile foundations under various types of loads is a necessary prerequisite to analyze and design them properly. Therefore, this paper highlights and compares the provisions available in Indian Standard IS 2911:2010 to estimate the capacity of laterally loaded pile foundation with the provisions available in different country codes and existing literature. Comparisons are made between the Indian standard method, Broms method and Matlock & Reese method for the analysis of laterally loaded piles due to popularity and prevalence of the later methods in design offices worldwide. This has been achieved using a parametric study on pile embedded in pre-consolidated clay and sand for both fixed head and free head case in terms of displacement and ultimate load capacity. It has been found that there are various limitations to the Indian Standard method associated with various cases such as short pile analysis, complete moment distribution etc. Therefore, suitable recommendations have been made on the basis of the above comparison to improve the accuracy of the design in Indian perspective. The proposed comparison and subsequent area of improvements will present the design engineers all across the globe, a broad sight of design specifications of laterally loaded piles.INTRODUCTIONPiles in groups are very often subjected to both axial and lateral loads. In the 1960’s, designers used to assume that the piles could carry only axial loads and the lateral load is to be carried by batter piles. However, later, a large number of load tests authenticated that vertical piles also can transfer lateral loads through shear, bending, and lateral soil resistance rather than purely acting as axially loaded members. Initial attempts to analyze laterally loaded piles used the finite-difference method, as described by Howe (1955), Matlock and Reese (1960), and Bowles (1968). Matlock and Reese (1956) used the finite difference method to get a series of non-dimensional curves to enable the user to input the appropriate curve with the given lateral load and estimate the ground-line deflection and maximum bending moment in the pile shaft. Later, Matlock and Reese (1960) extended the earlier curves to include selected variations of soil modulus with depth."

Jan 1, 2017

At its Port Kembla Plant, Australian Fertilizers Ltd. manufactures Superphosphate and other Phosphatic Fertilizers.Phosphate Rock is received from Nauru and Ocean Island. It contains water insoluble tri-calcium phosphate, Ca3(PO4), to an average of about 86%.It is crushed to pass a 20-mesh x 26-gauge woven wire screen, and is then treated with Sulphuric Acid to give the product Superphosphate with a water solubie prosphate content of 20.5%, estimated as P205. Sulphuric Acid is made by the chamber process. Three sets of chambers are installed, on,e five-chamber set of timber frame work construction and the other two of more recent date, each with four chambers of steel frame work construction. A fourth chamber set is now being built.Sulphuric Acid is delivered for use. at about 70% H2S04, the strength depending upon the rock used.Mixing - The crushed rock and sulphuric acid are mixed in weighed and measured proportions respectiyely in one-ton batches in revolving cast fron pans, mechanically stirred. The mixture, while still slurry, is run into a closed horizontal concrete cylinder (den) where, with the completion of the chemical reaction, it rapidly sets as Superphosphate.Approximately fifty batches are required to fill a den. When full, the den is opened ana the mass cut out by a revolving cutter. The product is elevated and conveyed to any required position in the Superphosphate storage shed, where it dries and matures.Despatch - As required, the Superphosphate is excavated by a two ton grab and conveyed from the matured "dump" to bagging units where it is disintegrated, screened and bagged at twelve bags to the ton. The filled !Jags are closed by machine and delivered to railway trucks immediately.Mixed Fertilizers - Sulphate of Ammonia, Sulphate and Muriate, of Potash, and Blood and Bone are mixed with Superphosphate and thoroughly incorporated to give different mixtures to meet special plant requirements.

Jan 1, 1938

By F. Lindroos

A cornerstone in the LKAB Green Pellet concept is to produce pellets with a small footprint in terms of energy con-sumption, CO2 emission and emission of other elements harmful to the environment, like dust, sulphur dioxides, nitrogen oxides, chloride and fluorine. The concept also encompasses our determination to make pellet products that contribute to low environmental impact and low energy consumption in our customer?s processes. The presentation will focus on the pelletizing process. It will describe both how we have attempted to decrease the generation of unwanted components in the process gas, and how we have tested or evaluated equipment for external gas cleaning. We will discuss and give examples from recent and on-going efforts and outline some of the future challenges we see, to meet our own environmental standards and also the tough demands imposed by EU and national legislation, while striving to boost production.

May 1, 2011

"Lax, misguided, and dangerous" is Rep. James Santini's description of the official US position on strategic nonfuel minerals. Santini (D-NV), chairman of the House Mines and Mining Subcommittee, criticized the Interior Department for "its long record of benign neglect" regarding the domestic minerals crisis. Santini made his remarks at a news conference at the American Mining Congress convention in San Francisco, where he released his subcommittee report "US Minerals Vulnerability: National Policy Implications." The report-said to be the first major congressional study of the minerals issue by a committee of jurisdiction is the result of a two-year inquiry. The investigation was undertaken, according to the chairman, "because no person or agency in the executive branch of government fully grasps the critical importance of nonfuel minerals to the nation's economy, defense, and quality of life." The report also urges a larger role for the Department of Defense, which has "stood passively by for many years as a consuming by-stander," according to the report. President Carter's incomplete Non-fuel Minerals Policy Review also drew the committee's ire; Santini calls it "a tragic waste that cost tax-payers $3.5 million and the loss of some 13,000 person-days." The subcommittee examined the following issues for its report: • The US minerals industry's inability to meet national raw material needs under a "hodgepodge of contradictory, restrictive, and irrational" federal regulations; • Dependency on foreign sources of strategic minerals in times of "increasing resource nationalism" and "Soviet mineral expansionism;" • National security needs for foreign mineral resources that do not have effective substitutes; • The US government's approach to national minerals policy "amid a growing realization that such a policy does not exist." The subcommittee report includes an analysis of public and private studies on nonfuel minerals and discusses a series of policy problem areas that negatively affect domestic production. Capital formation disincentives, tax policies, antitrust enforcement, environmental laws, health and safety regulations, technical problems, and restricted access to federally-controlled public lands contribute to what Santini calls a "tragic irony." "The irony is that we are a nation vastly rich in mineral resources yet our own government chooses to stifle development of these critical raw materials and thereby increase offshore reliance. The tragedy is that we also are ensuring US vulnerability to severe economic dislocations and a weakening of our national security." In just six years, from 1973-1978, the US trade deficit in nonfuel minerals rose from $2 billion per year to $8 billion, according to the report. The country imports more than 50% of 23 critical minerals, including 100% of its manganese, chromium, cobalt and platinum. The US is promoting its dependence on foreign mineral sources at the very time the security of many of those sources is becoming less certain, the report notes. Santini said the subcommittee investigation revealed a vulnerability that may be more serious and pervasive than that of foreign oil. The US may be able to develop alternate energy resources, but there are no effective substitutes for many nonfuel minerals. The report also discloses that US stockpiles of critical and strategic minerals are of inadequate supply and quality. Holdings of some vital minerals are far below present objectives, and for some there are no holdings at all, according to Santini. To resolve the current crisis, the report makes the following recommendations: • Complete immediately President Carter's Interagency Nonfuel Minerals Policy Review; • Implement (throught the Interior Department) the 1970 Mining and Minerals Policy Act; • Create an Office of Energy and Minerals with the same stature, power, and oversight responsibilities as the Council on Environmental Quality; • Ease federal restrictions on mineral exploration and development on public lands and implement a complete review of public land use policies; •Fund for and fulfill US nonfuel minerals stockpiling objectives; •Increase federal funding for non-

Jan 11, 1980

By I. V. Lunkin, E. B. Rakishev, B. R. Rakishev

In mining the method of statistical tests is used by solving of problems, exposing to influence of random factors. Such problems are: rational selection of equipment set; co-ordination in time of different processes; interaction between some processes and kinds of works. Usually it is considered that Monte Carlo method proves its value in the first place in that problems, which allow theoretical-probabilistic description. Analysis of numerical solution of mining-economic problems shows that the method of statistical tests may be used successfully by solving of determinate problems, which are solved usually analytically or by the methods of mathematical programming. We are talking about the problems of optimal use of resources, expedient placing of equipment, effective use of investments, rational planning of stripping and extracting works, groups of mining enterprises and about different variants of transport problem. In the report possibility of the method use is studied at an example of typical technical-economic problems solving. By solving of these problems the variant of the method with uniform distribution of random quantity had been applied and built-in random number generator of visual modelling system VisSim had been used. By algorithms elaboration it seems very perspective to use combination of the Monte Carlo method with traditional methods of numerical solving of the problems (methods of linear, nonlinear and dynamic programming and so on). Keywords: method of statistical tests, mining-technical problems, diapason of random number sample, efficiency function and its extremum.

Jan 1, 2003

By Don Z. Painter, Gordon F. Revey

Frontier/Traylor Joint Venture is presently constructing a section of the Tri-County Metropolitan Transit District of Oregon's (TRI-MET) Westside Light Rail system. This new section will extend Portland's existing transit system to the western suburbs of Beaverton and Hillsboro. The drill-blast excavations at this project include 10,000 feet of 20 foot tunnel, 18 cross passages, three shafts, an underground railway station, and a U-wall open cut. From a blast designer's perspective, this job has been extremely challenging. Blast vibration is limited to 0.5 ips at 200 feet or at the nearest structure, and airblast is limited to 129 dB -- linear peak and 96 dB -- C scale. The tunnels pass under heavily built up areas and have top of tunnel to surface cover distances as low as 70 feet. Surface blasting in the 26,000 cubic yard U-wall excavation was limited to five short nighttime periods due to its proximity to the very busy highway 26.

Jan 1, 1995

By Dachun Liu, Baoqiang Xu, Bin Yang, Yong Deng, Heng Xiong, Xiumin Chen

"In this paper, vacuum distillation technology has been employed to study the possibility and regularity of separating copper and enriching lead, silver and other valuable metals from copper- based multi component alloys. The result of experiment indicated the practicability of vacuum distillation dealing with copper base complex multi-component alloy to separating lead and silver, when the vacuum distillation temperature was 1637K, distillation time was 60min; residual gas pressure was 20-30Pa, the removal rate of silver was 95.86%, of lead was 99.63%; the evaporation rate of copper was 0.745%. The removal rate of arsenic, antimony and tin respectively were 83.09%, 48.12% and 24.54%. Vacuum distillation method is applicable for dealing with the copper-based multi component alloys, silver and lead can realize effective recovery.IntroductionCopper generally go with lead mineral, therefore, to remove copper from lead becomes an inevitable link in lead smelting. Dross from removed copper usually contains lead, arsenic, antimony, tin and noble metal silver. In abroad, soda ash-iron dust is adopted to process copper dross of this kind. The outcomes of this process are lead matte, wet lead, scoria smoke dust etc[1~5] The dominant components of all the outcomes are copper and lead. Moreover, in the process of tin smelting, copper contained by-products are produced, such as, crude tin alloy, tin lead electrolytic anode slime and so on. Copper content of all the products are ranging from few percentages to several tens percentage. Those products, no matter merge into main producing process, or separate treatment cost losses of valuable metal. For one hand, the containing of copper of outcomes from pyrogenic attack is less than 50%, for the other hand, a lot of valuable metal need to be processed, which increase the cost of retrieve."

Jan 1, 2013

By Nuno Cruz, Saúl Rodríguez

"When executing offshore bored piles there are several specific factors and problems to consider in order to guarantee excavation stability. One of the methods employed to carry out this type of work consists in setting up a floating work platform, typically a barge, and implementing a soil stabilization system that combines a partial steel guiding casing with third generation polymeric drilling fluids. The main aspects to take into consideration when performing offshore pile boring works are soil stabilization, project design, work methodology and operational aspects. An example of a work methodology problem arises before any pile boring work takes place as the steel guiding casing contains water, sometimes salt water. What to do with this water in order to replace it by an adequate polymer fluid will determine the stabilization capacity as soon as the shaft advances below the protection of the casing. Another example of operational problem may derive from barge movements while executing boring activities. This study is the result of extensive field data collection and concrete logging analysis from marine projects using polymers in different continents. The bored pile stability target was set ranging between 2% to 15% of concrete overbreak. Values above 15% or below 2% mean that there is a stability problem. Then the off-target pile’s data is collected, analyzed and classified under categories. Thus, a direct correlation is established between the problem category and the final results. Modifying steps in the pre-established construction methods or operational variables guarantees target results without the need to replace the approved construction methods. As a general conclusion, the worldwide experience in large diameter marine works, allows to provide truthful information and solutions for these problems. In knowing how to follow a logical sequence of work and applying adequate work methodology will be the key for success.GENERALBackgroundTo carry out the drilling process of offshore bored piles there are two main options to take into consideration: drilling the pile by using full guiding casing until final depth; or using a combined system of partial steel guiding casing and support drilling fluids.The knowledge and situations described in this paper come from the experience acquired in different projects where the second method was employed. This construction method consists in installing a steel guiding casing by vibration and thus covering the water table and further stabilizing the soil below it with polymeric fluids until reaching the pile’s final depth. The Fig. 1 schematic shows an example of this method where H corresponds to the length of the steel guiding casing whereas the remainder of the shaft’s length is stabilized by polymer fluid. The entire bored length is full of slurry up to top of casing.In most cases this kind of civil works results from the need to build a bridge or executing port structures in places where the creation of temporary artificial peninsulas with fill material is impracticable or not allowed. Hence the need to use floating work platforms, commonly referred to as barges."

Jan 1, 2017

By R. Flatabø, K-E. Johansen, L. Hunsbedt, P. M. Cowx, J. A. Bustnes

Eramet and Tinfos are two producers of manganese alloys in Norway, which have worked hard for several decades to improve both the internal and external environment. Furnaces producing ferro- and silico- manganese alloys generate large amounts of off-gas that contains substantial amounts of dust, heavy metals and organic by-products. The dust is separated from the gas in venturi scrubbers by washing with water. The water is cleaned and recirculated, and the surplus water coming from moisture in the raw materials, is discharged to the adjacent fjords after further treatment. Emission figures show that the discharge of suspended solids, manganese, zinc and PAH (polycyclic aromatic hydrocarbons) have been reduced substantially over the last three decades as a result of process improvements and installation of state of the art environmental control measures. The two plants were the first world wide to install mercury cleaning of the off-gases from the furnaces. Mercury emission reduction has exceeded 90%. Concerning other environmental issues, such as utilisation of off-gases for energy recovery and chemical purposes, both plants have achieved good results. Major effort in the environmental work has come from the plants themselves, but other players like FFF, The Norwegian Ferroalloy Producers Research Association, and SFT, The Norwegian Pollution Control Authority, have contributed to the achieved results.

Jan 1, 2007

By G. Wendel

Uranium is a naturally occurring radioactive material in the earth?s crust. Geological processes have resulted in concentration of uranium into ore mined for its gold content in South Africa. This uranium is present in the form of discrete particles of uranium minerals, generally oxides, which are normally insoluble. Chemical and physical processes during gold mining and extraction, particularly when carried out in conjunction with uranium extraction and sulphuric acid manufacture, act on the uranium minerals and the radioactive decay products of uranium. This may result insignificant accumulations of radioactive materials in certain parts of the process. There are a number of naturally occurring radioactive materials in the earth?s crust, such as Uranium-235, Thorium-232, andPotassium-40. This paper focuses on Uranium-238, together with its decay products, and how they affect the gold mines. Water plays a significant role in the redistribution of radionuclides, both as a physical transport medium, and as a solvent in which chemical reactions take place.

Jan 1, 1998

By C A. Locke, A B. Christie, J Cassidy, J L. Mauk

New and existing gravity and aeromagnetic data are used to determine the structure of the Waihi region and to investigate any relationship between structure, hydrothermal alteration and epithermal mineralisation. The 24 mGal, 10 km diameter, negative Bouguer gravity anomaly which occurs south of Waihi has been modelled as a I.5 km deep asymmetrical basin. This basin, the Waihi Depression, is interpreted to be infilled with low-density volcanic rocks of the Uretara Formation and Whitianga Group, overlying older andesites of the Waipupu Formation. To the north and west, the margins of the depression are defined by the Waihi and Mangakino Faults, which have been modelled with dips of 45 - 60¦ to the south and west respectively. The southern and eastern boundaries of the Waihi Depression are defined by smooth, shallow dipping (15 - 20¦) boundaries. The Waihi Depression is interpreted as a fault-angle depression, resulting from southeast extension in the early Pliocene. The Waihi Fault is modelled as an approximately E-W feature, located to the south of Waihi. Small 2 - 4 mGal positive Bouguer gravity anomalies occur north and west of the margins of the depression, and correlate with known areas of hydrothermal alteration and areas of low magnetic gradient.

Jan 1, 2003

By C. F. Vos

Small replacements of C12-trithiocarbonate (C12-TTC) for dithiocarbonate (DTC)/dithiophosphate (DTP) in a reagent suite for the flotation of platinum group metals (PGM) have significantly improved the rejection of gangue. Coupled to this is an improvement in kinetics, grade and recovery of PGMs. In a pilot-plant trial, after a 5 mole per cent replacement of the current DTC/DTP collector combination by C12-TTC, large opaque bubbles were replaced by small clear ones. In addition, a similar flotation response was realized with one-third of the current depressant dosage. During a preliminary plant trial on underground UG2 ore, the initial rougher concentrates were characterized by higher PGM concentrate grades and this was in part due to improved chromiter ejection. The concentrate produced from the TTC trial also exhibited a much finer particle size distribution. The overall circuit performance, which included secondary regrind and flotation, showed an increase in concentrate grade of approximately 44% while the tailings grade remained unchanged

Jan 1, 2007

The slags produced by the Imperial Smelting Process (ISP) are based on the system ZnO-?FeO?-Al2O3-CaO-SiO2. The slag chemistry is important to the process since it determines the fluxing practice and the operating temperature of the furnace required to produce fluid slag. The paper presents the results of the first systematic experimental investigation of these ZnO-containing slags in equilibrium with metallic iron, and provides information on the primary phase fields and liquidus temperatures in these slags over the range of compositions used in ISP practice. A feature of the slags is the presence of alumina, which has a major influence instabilizing the spinel phase. This information presented in the form of pseudo-ternary sections ZnO-?FeO?-(Al2O3+CaO+SiO2) enabling the data to be readily used by plant engineers. Keywords: liquidus temperature, ISP, EPMA, ZnO-?FeO?-Al2O3-CaO-SiO2, phase equilibria.

Jan 1, 2004

By K Williams, W Chen, J Miller

The flow function of an iron ore material governs its flowability characteristics in material handling chains within the resource industry. A uniaxial compression test is able to obtain a flow function more rapidly comparing to the Jenike direct shear test; nevertheless, the results often exhibit lower rankings using the former method. This study aims to investigate the fundamental stress states within the test specimen that lead to this phenomenon, and to introduce a new uniform density specimen preparation method for a uniaxial compression test, in order to achieve comparative flow functions as for a Jenike direct shear test. The minimisation of the wall friction effect and achievement of the critical state when preparing a uniaxial specimen are explicitly discussed. Experimental investigations on flow functions of a suite of Australian iron ore samples were conducted using both the uniform density uniaxial compression test and the Jenike direct shear test. Results from both methods were found to be comparable, providing the specimen exhibits cohesive flow behaviours. The outcome of this research enabled development of a rapid and reliable flow function testing method for cohesive iron ore materials.CITATION:Chen, W, Williams, K, Roberts, A and Miller, J, 2017. Rapid and reliable flow property testing – a modified uniaxial approach, in Proceedings Iron Ore 2017, pp 149–154 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 24, 2017

By Charles Pretorius

Electronic Delay Detonators (EDDs) with remote wireless programming and initiation capabilities have been successfully used for almost two years now. This system has been used in blasts mainly in South Africa, but also in South America and other countries in Africa. Initially the industry was slow to accept the idea of remote programming and blasting. The advantages were not fully understood and there were some safety concerns. With close to 200 successful blasts as a reference, a much better understanding exists. The advantage of such a system becomes even more significant when the programming of the detonators is digitally integrated with the blast design software as used by the Blast Engineer. It is now possible to import a survey file into the blast design software, to do the blast design using actual hole positions and to then export the designed firing times directly to the detonators down the hole via remote wireless communication. Mines that have been exposed to this technology favour it to the extent that wireless centralised programming is becoming the norm against which other electronic delay detonator technologies are measured.

Jan 1, 2005

By A. G. Pasamehmetoglu

This paper describes the conver¬gence and load measurements carried out in inclined seams at five longwall faces, two of which were supported by hydraulic props and the other three by conventional timber supports in Karadon-Gelik mine. The minimum support capacities determined in this study are compared with the results obtained from two empirical approaches suggested by Wilson (1975) and Jacobi (1981). The characteristics of hydraulic props to be used and support patterns in the longwalls are found, conclu¬sions are drawn and suggestions are made. Design nomograms are prepared for field engineers, in order to be able to approach the problem more confidently and realistically.

Jan 1, 1992