Stripping Ratio Research Articles

Study of Mold Oscillation Parameters and Modes on Slag Lubrication in Slab Continuous Casting

The effects of mold oscillation parameters and modes on slag lubrication were quantified based on a verified multi-phase model for liquid slag infiltration during continuous casting. The main results indicated that the variations of slag film thickness, slag consumption, and heat flux at the meniscus were generally periodic with the mold oscillation. For sinusoidal oscillation, shorter amplitude or lower frequency consumed much more liquid slag. Non-sinusoidal mode could increase the slag consumption from 0.274 kg/m2 to 0.286 kg/m2, an approximately 4.4% increase over that of the conventional mode. The evolution of heat flux at the meniscus fluctuated severely with lower oscillation frequency, while the non-sinusoidal mode was stable, approximately 1.6 MW/m2. This study demonstrated that the positive strip time contributed more to lubrication than the negative strip time and that the slag consumption decreased with an increase of negative strip ratio in mold oscillation.

Removal of Cadmium from Cobalt Sulfate by Solvent Extraction Using Cyanex 301

A variety of reagents, including P204, P507, and Cyanex 301, were used for extraction of cobalt and cadmium from cobalt sulfate solution. It was found that Cyanex 301 exhibited the best separation efficiency for cadmium and cobalt from solution containing 90 g L−1 Co and 3 g L−1. The effects of initial pH, extractant concentration, phase ratio, extraction time, and temperature on the cadmium and cobalt extraction ratios were examined. The results showed that the extraction ratios of cadmium and cobalt were 99.95% and 2.45% under the optimal conditions of pH 1.8, 10% Cyanex 301, O/A = 1:1, T = 25°C, and t = 10 min. The species of Cyanex 301 chelated with cadmium or cobalt were proposed to be Cd[Cyanex 301]2.5 and Co[Cyanex 301]2. The stripping ratios of cadmium and cobalt were 99.9% and 95% using 7 mol L−1 hydrochloric acid, respectively, indicating effective separation of cadmium from high-concentration cobalt sulfate solution.

Sustainable lignite resource planning at Thar coalfield, Pakistan

Thar coalfield is a new coalfield in Pakistan with estimated lignite resource of more than 175 billion tons. Resource planning is an essential part of the strategic plan for optimal and economical exploitation of Thar lignite. Main objective of the present research is to assess Thar coalfield as a single deposit and identify the areas suitable for surface mining, underground mining and waste dump at Thar coalfield. The cumulative stripping ratio distribution map has been developed for Thar coalfield, covering an area of 1691.04 km2 around 12 exploratory blocks. Lithological data of 693 drill holes have been used to calculate the cumulative stripping ratio in every borehole, which varies from 3.7 m:m to 88.1 m:m with an average value of 12.85 m:m. Cumulative stripping ratio is divided into six ranges, viz: 4–6, 6–8, 8–10, 10–15, 15–20 and >20 m:m. Contours are digitized around all boreholes showing various ranges of stripping ratios. From the cumulative stripping ratio distribution map, it is concluded that 665.72 km2 area, which constitutes 39.37% of the total assessed area, is suitable for surface mining and 989.82 km2 area, constituting 58.53%, is appropriate for underground mining and outside waste dumps. Whereas, 2.1% area is no coal zone, only suitable for outside waste dumping. The developed map of cumulative stripping ratio distribution may be used as a guide map for the preparation of mining master plan for Thar coalfield.

Investment estimation and acceptance of State Tax Instead of coal mining business license Clear and Clean in West Sumatra Province

This research conceptual measurement simulation for financial component which is needed for investment and benefit simulation held by stated that taken from company obligation categorized as non tax for mining activities predicated with cnc at West Sumatera Province. This simulation connected with capital investment and operational activities that influenced by coal getting stripping ratio, coal hauling and other financial related. This simulation only values stated income non tax and royalty. Analysis methods using from several document feasibiliy study from coal company has already operated, and also estimation for all investment component and components of income stated non tax. Accuracy data accepted for this research at least 30% from all investment. Estimation starting from deciding production target, life mining period, investment needs, financial operation and other financial activities, and comparison with theoritical measurement. The comparison result then used to make another financial model simulation. At the last, this research will present economy simulation model created from mining operational activities in west sumatera province to estimate stated income non tax from mining production operational. Using sensitivity analysis, shows that the change of coal selling prices will gives significant influence to NPV project and stated incomen non tax.

Ore Reserve Estimation of Saprolite Nickel Using Inverse Distance Method in PIT Block 3A Banggai Area Central Sulawesi

Reserve estimation is one of important work in evaluating a mining project. It is estimation of the quality and quantity of the presence of minerals have economic value. Reserve calculation method plays an important role in determining the efficiency in commercial exploration of a deposit. This study was intended to calculate ore reserves contained in the study area especially Pit Block 3A. Nickel ore reserve was estimated by using detailed exploration data, processing by using Surpac 6.2 by Inverse Distance Weight: Squared Power estimation method. Ore estimation result obtained from 30 drilling data was 76453.5 ton of Saprolite with density of 1.5 ton/m3 and COG (Cut Off Grade) Ni ≥ 1.6 %, while overburden data was 112,570.8 tons with waste rock density of 1.2 ton/m3 . Striping Ratio (SR) was 1.47 : 1 smaller than Stripping Ratio ( SR ) were set of 1.60 : 1.

Geotechnical Investigations - A Tool for Deciding Mining Method for Chromite Deposits in Odisha State, India

The Chromite deposits of Sukinda valley, Odisha, India are of strategic importance for the development of ferro-alloy industries. Around 90% of the India’s chromite ore production derived from two important chromite bearing belts, namely the Baula-Nuasahi belt and Sukinda valley ultramafic complex deposit. In terms of rock strength properties, the host rocks and ore body at Baula – Nuasahi chromite belt are hard and compact, with some structural defects such as joints, faults and dykes. After extracting the chromite ore by surface mining up to the economic pit bottom, the remaining reserves were being mined by underground method. In the Sukinda valley chromite deposits, both the wall rocks and ore body are weak, highly weathered. These mines were operated by opencast method. As most of the working mines in Sukinda valley reached their economic pit limit and there is no further scope to extract the ore by opencast mining. Since the chromite ore bodies are having considerable mineable strike length, width, and depth persistence, there is no option except to convert them into underground mines to increase the life of the mines. The chromite ore bodies were proved up to depth of 270m by exploratory drilling. Some major mining companies are planning for underground mining operations, due to constraint of limited space available for waste dumping, working with common lease boundary, slope instability, high volume of stripping ratio. To overcome such problems, the basic step is to conduct the detailed geo-technical investigations to avoid any unexpected consequences during mine development and stoping operations. The geo-technical investigations comprised of geotechnical mapping of existing mined out benches using scan line surveys, geo-technical drilling and logging of cores for the estimation of RQD, structural discontinuities, testing of cores for material properties followed by performing numerical modeling to evolve a suitable stoping method and excavation geometry. The paper deals with the results of the geo-technical investigations carried out for the planning and design of underground mine workings, design of stope parameters based on the geo-mining conditions.

The effect of mine aging on the evolution of environmental footprint indicators in the Chilean copper mining industry 2001–2015

Abundant evidence suggests that the massive global exploitation of copper mines over the last two decades led to mine aging expressed as ore grade reduction, deepening of open pits and underground operations, hardening of the rock, and increasing stripping ratios. These processes have affected the evolution and change of key environmental footprint indicators. Copper ore grade decline seems the most important of these factors and depends on variables including the rate of extraction, ore deposit geological features, introduction of new technologies, the copper price and its co-products, and the discovery and exploitation of new ore deposits. From 2001 to 2015 Chile increased its copper production by 22% and produced overall 80 million tons of copper, more than it produced in the entire 20th century. This paper explores the effects of mine aging on three key environmental footprint indicators: energy and water consumption, and greenhouse gas emissions. Electric energy consumption per ton of copper should grow in the coming decade at a significantly slower rate than in the last fifteen years because of the slowdown of the ore grade decline in mill concentrators. Additionally, a steeper decrease is expected for the emission of greenhouse gases per ton of copper.

Feasibility of electrokinetic in situ leaching of gold

Conventional gold mining operations are facing significant challenges due to declining ore grades and increasingly higher strip ratios. To meet global demands while limiting associated environmental impacts, alternative techniques to extract resources, including gold, are urgently needed. We suggest that in situ leaching coupled with electrokinetics (EK-ISL) could potentially enable recovery of gold from (subeconomic) ores with a significantly smaller environmental footprint than current mining techniques. EK-ISL would involve the leaching of gold, in situ, using a lixiviant that is introduced via a set of wells. A voltage gradient is applied to transport the lixiviant through the orebody. The gold is leached and also transported towards a set of recovery wells. At the surface the gold is recovered and the lixiviant can be recycled.This study was designed to verify the in-principle feasibility of this novel technique. A series of laboratory experiments was performed with an iodide/tri-iodide solution as lixiviant to extract gold from unconsolidated porous media. Experiments in which pyrite was included as proxy gangue mineral and complimentary bottle roll tests showed a declining efficiency of EK-ISL gold leaching with increasing pyrite oxidation. However, 80% gold recovery was still achieved, even with the highest tested pyrite concentration (5.26wt%). The coupled transport and reaction processes were interpreted and quantified through numerical model simulations that were constrained by the experimental observations. Overall the experimental and numerical modeling results suggest the in-principle feasibility of EK-ISL.

Pemodelan Perhitungan Cadangan Batubara Dengan Perangkat Lunak Pada PT. Mitra Abadi Mahakam Provinsi Kalimantan Selatan

This company needs reserves calculation before doing mining activities such as coal deposit model construction, coal reserves calculation. and Stripping Ratio (SR) value calculation. As a result, it obtains the number of coal reserves which will coal deposit model. This fact became the background of the study. The reserves calculation was carried out by Triangular Method supported by Minescape software. The coal reserves calculation and coal deposit model of Mitra Abadi Mahakam Ltd.. The research result was a coal model which can be seen from the pictures on map attached in this final project report. The coal reserve was 2,347,827.44 tons, while the overburden volume of mining activity site was 8,318,130.05 BCM" and the Striping Ratio was 3.5. Keywords: coal, model, reserve, overburden

Development of a goal programming model for optimization of truck allocation in open pit mines

Truck and shovel operations comprise approximately 60% of the total operating costs in open pit mines. In order to increase productivity and reduce the cost of mining operations, it is essential to manage the equipment used with high efficiency. In this work, the chance-constrained goal programing (CCGP) model presented by Michalakopoulos and Panagiotou is developed to determine an optimal truck allocation plan in open pit mines and reduce the waiting times of trucks and shovels. The developed goal programming (GP) model is established considering four desired goals: “maximizing shovel production”, “minimizing deviations in head grade”, “minimizing deviations in tonnage feed to the processing plants from the desired feed” and “minimizing truck operating costs”. To employ the developed model, a software is prepared in Visual Studio with C# programming language. In this computer program, the CPLEX optimizer software is incorporated for solving the developed goal programing model. The case study of Sungun copper mine is also considered to evaluate the presented GP model and prepared software. The results obtained indicate that the developed model increases the mine production above 20.6% with respect to the traditional truck allocation plan, while meeting the desired grade and the stripping ratio constraints.

Strategic Mine Planning Approach Applied to Large Scale Copper open Pit Mines by Comparing The Impact of three Different Bloc Models of the Same Deposit, On the Long Term Mine Plan

The Kamoto Oliveira Virgule (KOV) open pit mine is located at 300Km from Lubumbashi, second largest city of the Democratic Republic of the Congo, in the mineral rich province of the Lualaba (EX-Katanga province).KOV pit is located 10Km south of the Kolwezi town and it is essentially constituted of sedimental rock, in a major portion of the so called “Lambeau Geologique de Kolwezi”, which is a part of the well-known copperbelt mineralization. In 2006, a joint venture of Glencore, Gecamines (the DRC State owned Company), and Simco, took over the open pit mine, which was previously owned by Gecamines, and formed the Kamoto Copper Company (KCC).KOV open pit mine is classified as a large scale open pit mine due to his dimensions (approximately 2.5km East-West and 3Km North-South).the mine has also a high strip ratio ranging from 8 to 10 in some areas. At his initial stage (Prefeasibility study), SRK released a bloc model which is still be used by the Kamoto Copper Company (KCC), but since the geology department addressed the issue about grade control model ore discrepancies, when comparing it to the SRK model, the management hired another contractor that constructed another bloc model. Internal adjustments using the grade control model data to better predict tonnes and grades have been also implemented but reported very poor results .since reserves have been officially reported to the market in 2014 to the TSX, the reserve report had to remain consistent with the 2014 report, despite that the issue has been fixed ,it still for a matter of interest to conduct a comparative analysis, to check on the impact of the other bloc model on the life of mine and the mine schedule .since we know by comparison that the other model (OBM) has a difference in its 3D distribution of ore and waste material. This paper will be focused on determining the impact on the life of mine and the mine schedule of the KOV pit with regards of those differences, between the bloc models.Index Terms: Mine planning, mine scheduling, mine optimization, life of mine, ultimate pit.

An experimental study on shear strength of glubam

Glued-laminated bamboo (glubam) is a new type of structural material, which is developed as a potential alternative to the glued-laminated lumber or glulam. Similar to modern timber structures, connecting the glubam elements using steel joints requires a good understanding of the shear behavior of the material. In this study, glubam boards with three different bamboo strip (or fiber) configurations are manufactured and studied. Three types of glubam boards were manufactured and tested, including glubam with two bidirectional fiber arrangements at the ratios of 4:1 and 1:1, respectively, in the two orthogonal directions, and also the unidirectional fiber arrangement. The shear strengths in different loading conditions are experimentally investigated, following testing specifications for conventional wood. The study found that the in-plane shear strength values follow a normal distribution well, whereas the out-of-plane shear strength values can be statistically expressed by Weibull distribution. Based on the test results, the out-of-plane shear strengths and the in-plane shear strengths of glubam are studied, and the characteristic values and the design values are suggested. The relationship between the out-of-plane shear strength and the bidirectional ratio of bamboo strip (or fiber) has also been obtained with reasonably good correlation to the test results.

Point-of-Care vs Laboratory Based Urine Protein-Creatinine Ratio as an Indicator of Proteinuria in Pregnancy [9N

INTRODUCTION: Proteinuria is a hallmark finding in preeclampsia and a value of 300 mg or more in a 24 hour urine collection aids the diagnosis. A random urine protein-creatinine ratio (UPCR) of at least 0.3 mg/dL has emerged as a surrogate indicator of proteinuria. Point-of-care (POC) UPCR tests have been developed and may provide a convenient and timely extrapolation of proteinuria at the bedside. Although such testing has demonstrated excellent correlation with central laboratory methods in studies of non-pregnant patients, its validity and clinical utility have yet to be established in the pregnant population. Our objective was to evaluate POC UPCR as an indicator of proteinuria in pregnancy and compare it to the central laboratory method. METHODS: 108 urine samples from pregnant women presenting to triage for preeclampsia evaluation were collected prospectively from January to June 2015. For clinical purposes, a urine specimen was collected and sent to the laboratory for standard measurement of protein, creatinine and PC ratio using a Beckman Coulter Au5800, measuring turbidimetry by immunocomplexation with an anti-albumin antibody. A sample of the collected urine was tested via POC UPCR using Multistix Pro 11 reagent strips. Utilizing the manufacture interpretation guide, a “normal” strip ratio was defined as urine containing less than 300 mg protein/g creatinine. RESULTS: There was moderate agreement between POC UPCR and laboratory UPCR (k=0.512). After triage evaluation was complete, 31 women had a clinical diagnosis of preeclampsia. CONCLUSION: Results indicate that the POC UPCR is not reliable for the diagnosis of proteinuria when compared to the central laboratory UPCR.

Mechanical Properties and Formability of Ultrasonic Treated Twin Roll Casting Magnesium Alloy Sheet

The effects of ultrasonic treatment on the microstructure and properties of twin roll casting Mg-2.45%Al-0.92%Zn-0.69%Ce-0.21%Mn alloy strip were studied. The results show that the ultrasonic treatment improves strength, elongation and limiting drawing ratio of the alloy strip. The highest limiting drawing ratio of the sheet is 2.16 at 250 °C. The improvement of properties is attributed to the refinement of α -Mg grains and the modification of Mg 17 (Al, Zn) 12 and AlCeMn phases by ultrasonic treatment during the twin roll casting process. The grain size of the twin roll casting strip is refined from 150 μm to less than 30 μm with the ultrasonic treatment power of 800 W, and the needle-like shape of the AlCeMn phase is modified to a globular shape; therefore, the mechanical properties and formability of the magnesium alloy sheet are improved.

Optimisation study on coordinated mining model of coal reserves buried between adjacent surface mines

When coal excavations in two adjacent surface mines proceed in a parallel and equi-directional sequence, the stripping ratio in the overlapping section of two end walls is usually reduced; bring about remarkable economic benefits. A formula has been derived for calculating the effects of mining width on stripping ratio. An optimisation model of uncovered end-wall height and mining width is also constructed. Research results show that stripping ratio tends to decrease linearly and then increase at a slow rate as the mining width of reserves buried between adjacent surface mines (RBbASM) increases. When excavating the minimum RBbASM, there appears a stripping ratio surge. Therefore, this part of resource could not be considered for excavation. Heidaigou Surface Coal Mine (HSCM) and Ha'erwusu Surface Coal Mine (HeSCM) were selected as a case study, where the optimum uncovered end-wall height and the mining width of RBbASM are determined as 85.77 metres and 540 metres respectively. [Received: February 20, 2016; Accepted: September 5, 2016]

Determination of the optimum cut-off grades and production scheduling in multi-product open pit mines using imperialist competitive algorithm (ICA)

With regard to the immense importance of cut-off grade in designing and planning open pit mines, optimizing this parameter has considerable effects in mining economic. This paper describes objective function for single metal mines with multi-product. For this purpose, the operation process in mine No.1 of the Golgohar iron mine that produces three types of products (sizing, concentrate and pellet) for sales is used to model objective function. Then the Imperialist Competitive Algorithm (ICA) has been utilized to find out the optimum cut-off grades. Consequently, the optimum cut-off grades has been calculated between 40.5 and 47.5% and net present value has been obtained 18,142 billion Rial. In addition, production scheduling is carried out for five years mining plan pushback. Therefore, the average stripping ratio has been determined 1.41. The result shows that by stockpiling low-grade ore, concentrate plant can be fed by maximum capacity for one year addition to the primary plan.

Geometric Interpretation of Itakpe Open Pit Mine

In mine planning and design, it is of utmost importance to have the basic knowledge of geometry as it is necessary in the in the graphical representation of the mine and also in the estimation of the mine’s production rate. Using the limiting stripping ratio approach, I can establish the overall slope angle of the mine using the mine surface intercept method of which the overall slope should be inclined at an angle of 53⁰. The mine divided into benches of 10m intervals would enable easy estimation of the production rate as the given deepening rate would aid in calculations. All these would enable easy design of the mine as well as its planning prior to when production commences.

Determination of open pit diamond mine limits with regard to stripping time difference

The analysis of methods to account for stripping time difference at the stage of determination of limits in deep open pit mining reveals advantages and shortcomings of the methods and provides a principled approach to determination of a discount ultimate strip ratio for the most representative geological and geotechnical conditions of diamond-bearing ore bodies in the form of single pipes. Discounting of marginal strip ratios is based on adding the common formula with an average mean discount coefficient represented by a correlation of mining rate decrease, stripping zone height and highwall slope angle. It is shown that target variation of the factors included in the discount marginal strip ratio allows considerable influence on depth and efficiency of open pit mining.

A decision support system for determination of a sustainable pit limit

There is an increasing interest among practitioners to incorporate sustainability issues in evaluating the projects. However, it is a complex task to deal with the conflicting aspects of sustainable development. Nowadays, most of the minerals are produced by surface mining methods; where the economic, social and environmental impacts of these operations are closely related to Ultimate Pit Limit (UPL). UPL actuates the amount of mineable reserves, stripping ratio, location of waste dump and tailings dam, and the area of lands that will be disturbed at the end of a mining operation. Therefore, it has a significant contribution on the sustainability of the mining community. UPL determination is a strategic decision and it requires a Decision Support System (DSS) to evaluate and understand the outcome of each design alternative for optimal decision-making. In this DSS, after recognizing the indicators, it benefits from a matrix method to assess and measure the sustainability of different UPL alternatives based on subjective judgments. Moreover, some future information is unavailable and imprecise. In that regard, fuzzy logic is used to resolve uncertainties. Sungun Copper Mine data is used to show the effect of considering sustainability issues in UPL determination. The selected UPL changes net present value (NPV) and the mine life by 7% and 13 years respectively compared to the case where just economic issues are considered. The system shows to be efficient in assessing the sustainability issues of design alternatives during the feasibility studies.

New occurrence of potential phosphate resource in northeast Jordan

An exploration program aided by field investigation, exploration drilling, detailed sampling, lithological and petrological studies, geochemical investigation, and resource calculation leads to the discovery of a potential phosphate resource in northeast Jordan close to the international border with Saudi Arabia and Iraq. The studied phosphate is of the Middle Eocene age that belongs to the Wadi Shallala Formation. It is equivalent to the phosphate deposits recorded in the lower part of the Umm Wual Formation in the Turayf region of Saudi Arabia and the Eocene Ratga Formation in the Ethna phosphate deposit west of Iraq. The phosphorites in the region are broadly similar in mineralogical composition and geochemical affinities. X-ray diffraction indicates the presence of francolite with variable amounts of calcite and quartz. Most samples consist of phosphate clasts embedded in carbonate and silica matrix and cement. P2O5 content is up to 32.3 % with an average equal to 18.6 %. The impurity is caused by the presence of variable amounts of SiO2 and CaO. The F% and F/P2O5 ratio in studied phosphates is lower compared with that in phosphates from Jordan and Saudi Arabia. The geological and geochemical results were integrated for resource estimation. Three high-grade phosphate layers with ≥23 % P2O5 were considered in the calculations. The phosphate resource is classified as an inferred resource. The total volume of the resource is about 649 million tons. The average P2O5 content is 24.57, and the stripping ratio is 1:5.8.