A Vertical Mining System Concept Using DTH for Seafloor Mining

During the drilling of the bone, the temperature could increase above 47 degrees C and cause irreversible osteonecrosis. The result is weakened contact of implants with bone and possible loss of rigid fixation. The aim of this study was to find an optimal condition where the increase in bone temperature during bone drilling process would be minimal. Influence of different drill parameters was evaluated on the increase of bone temperature. Drill diameters were 2.5, 3.2 and 4.5 mm; drill speed 188, 462, 1,140 and 1,820 rpm; feed-rate 24, 56, 84 and 196 mm/min; drill point angle 80 degrees , 100 degrees and 120 degrees and external irrigation with water of 26 degrees C. Combinations of drill speed and drill diameter with the use of external irrigation produced temperatures far below critical. Without external irrigation, temperature values for the same combination of parameters ranged 31.4-55.5 degrees C. Temperatures above critical were recorded using 4.5 mm drill with higher drill speeds (1,140 and 1,820 rpm). There was no statistical significance of different drill point angles on the increase or decrease of bone temperature. The higher the feed-rate the lower the increase of bone temperature. The external irrigation is the most important cooling factor. With all combinations of parameters used, external irrigation maintained the bone temperature below 47 degrees C. The increase in drill diameter and drill speed caused increase in bone temperature. The changes in drill point angle did not show significant influence in the increase of the bone temperature. With the increase in feed-rate, increase in bone temperature is lower.

Sensitivity analysis of drill wear and optimization using Adaptive Neuro fuzzy –genetic algorithm technique toward sustainable machining

The main affecting parameter for Delamination of the composites and in turn the failure of composites is the Thrust force. In the present work an attempt has been made in order to investigate the Thrust force generated during drilling of the TiO2 and ZnS filled Glass Fabric Reinforced Polymer Matrix Composites (GFRP). The volume fractions in the matrix were chosen as 1, 2 and3%. A plan of experiments, based on the techniques of Taguchi, was performed to acquire data in a controlled way. An L27 orthogonal array and analysis of variance (ANOVA) were employed to investigate the influence of process parameters on the drilling of these composites. Drilling has been conducted on a radial drilling machine. Speed of drilling (S), volume fractions (VF) and drill tool diameter (D) were considered as the varying parameters with three levels. Thrust force has been considered as the output parameter and is been measured in each combination of parameters chosen. Results reveal that, the addition of filler will increase the thrust force developed during drilling. As per ANOVA values, drill tool diameter contributes more towards generation of thrust, followed by speed of drilling. Main Effect plots shows that, contribution of speed towards thrust generation is only upto a certain level of increase in speed.

In order to express how much the drill selection depends on the rock properties and its effect on the percentage of core and drilling speed, diamond drill selection and drilling mechanisms are taken. In diamond drills, enough pressure should be applied to ensure that each active diamond grain sinks into the rock for the best drilling speed. This stress should be above the surface strength of the rock to be drilled and below the diamond grain strength. The main goal to be achieved in engineering and research and development studies is to ensure that both the designed system and the product to be developed have maximum performance. In order to reveal the conditions in which the best results will be obtained, first the feature that determines the performance is determined and the factors affecting this feature are examined. Then, experiments are carried out to determine the effects of these factors on the feature that determines the performance and to find the most suitable combination (by taking into account the uncontrollable factors). Optimum conditions are determined by evaluating the performance indicator obtained as a result of the experiments. The experiments carried out within the framework of this approach can be perceived as the question asked to the system, and the results of the experiments as the answer given by the system. The critical point is that it is necessary to ask the right question in order to get the right answer. Drilling is a complex event influenced by many factors. Drill type and diameter, rotational speed, pressing force, torque and circulating fluid are controllable parameters. On the other hand, physic mechanical properties of the rock and geological conditions (uncontrollable factors such as discontinuities, bedding conditions, grain size, matrix structure, porosity, cementation degree and abrasive mineral ratio) affect rock drill ability. The drill ability of rocks can be defined by various concepts such as feed rate, drill wear amount, drill life and tooth penetration. Drilling method classification can be made according to several criteria. The most logical classification can be made according to the type of energy required for rock fragmentation. Drilling is done in rocks for many purposes and many methods developed for this purpose have successfully drilled into rocks. Many new methods in rock drilling have been acquired through experience. The most successful practical application is the mechanical shredding process. Although it is mostly applied for cutting soft rocks, this method is done by spraying high pressure water. Keywords: drilling, drilling process, drilling operations, tools, drilling mechanism, drilling diamond.

In recent years, the application of polymer composites has been enormously increased particularly in aerospace as well as in automobile sector due to its light weight, high specific stiffness and high specific strength. Machining of those composites has really become an emerging area of research. A considerable volume of research has already been carried out by the pioneers in order to study machining and machinability aspects of these composites, thereby, maintaining both product quality as well as productivity. Drilling is considered as one of the most common machining processes for assembly of composites. In case of fiber reinforced polymer (FRP) composites, delamination and fiber pull out are the major problems that arise during drilling operations. Defect free drilling whilst ensuring satisfactory machining performance (in terms of quality as well as productivity) is definitely a challenging task. In this context, the present study mainly attempts to reduce drilling induced damages and at the same time to improve machining performances during drilling of polymer composites by determining an optimal parametric combination in view of multiple process responses and by considering effects of drilling process control parameters, drill geometry (diameter of drill bit) as well as composite type. Attempt has also been made to understand the relationship (influence) between input-output(s); where, inputs i.e. process parameters have been considered like composite type, drill speed, feed rate, drill diameter and outputs have been and drilling responses like thrust force, torque, delamination at entry and exit and average surface roughness of the drilled hole. Multi-response optimization has been performed using Deng's similarity based method in combination with Taguchi's optimization philosophy. Results obtained thereof have been compared with TOPSIS (Technique for Order Preference by Similarity to Ideal Solution)-based Taguchi approach.

Sand production is a major concern for many operators. It can impact production, cause erosion in downhole and surface facilities, require additional separation and disposal, and lead to significant economic loss. On the other hand, precautionary but unnecessary sand prevention will mean unwarranted reduction in productivity. Reliable sanding prediction analysis thus provides a basis for designs that achieve appropriate sand management strategies and maximization of economic production, and overestimates or underestimates of sanding risk increase the chances of serious economical loss. This raises the question of how accurate and reliable sanding predictions might be achieved without overcomplicating the analyses and without requiring complex lab and field data that, in most instances, will be unavailable or the acquisition of which will incur unwanted delays and costs. This paper presents the case of a sanding study for the Messla field in Libya; a field that has produced oil for more than 30 years. This field experiences massive sanding from some wells but experiences no problems with other wells. This variation made the Messla field an ideal candidate for a detailed sanding and geomechanics investigation aimed at optimizing completions and production and at dramatically reducing the current sanding without having to enter into a lengthy data acquisition programme or time-consuming modelling. In this study, sanding prediction analyses were conducted using a technique that combines easily measurable lab data, log data, and analytical calculations with empirical methods that are supported by the results from previously run rigorous and advanced numerical code. The result of this integration is a sanding analyses tool that uses input parameters such as rock strength, geostresses, and particle size to: ■account for plasticity effects that modify the strength behaviour of sands surrounding openhole wells and perforations during drawdown to reduce uncertainty and conservatism such as seen in simple elastic models,■account for scale effects associated with different perforation and borehole diameters,■provide a significant improvement and predictive capability over simple empirical methods,■provide the above accuracies without needing complex or extensive lab programmes to determine advanced rock mechanics properties. The application of this approach to the Messla field and a later comparison of the results to actual field data and observations validated the analyses and methods used. The application and comparison also disclosed that the approach was not only able to provide results that closely matched field experience but was also able to predict correctly, to the year, the onset of sanding in wells. This paper describes the methods employed in this investigation, provides details of the data acquisition and processing required, and demonstrates that accurate sanding predictions can be achieved by focusing effort on certain input data, targeting and reducing specific uncertainties, and by employing pragmatic models that do not rely on over-complicated measurements and analyses.

Coal is an important resource for China and even for the whole world. With the improvement of mechanization, automation and intelligence of coal mining equipment in China, there has been an imbalance between the speed of mining and of excavating. Adopting efficient cutting paths is beneficial to improving roadway excavation efficiency and alleviating the imbalance between mining and excavation. In this paper, taking the 12307 belt roadway of Wangjialing Coal Mine as the research background, the geomechanical parameters and distribution characteristics of the surrounding rock were observed and studied, and the test results of in-situ stress, surrounding rock structure and surrounding rock strength were obtained. Based on the test results, a numerical model was established, and the stress and displacement distribution law of the surrounding rock of the roadway under different cutting paths were analyzed, and two optimal cutting paths were proposed based on the actual situation, and industrial tests were carried out. The test results show that using the “snake” cutting path from bottom to top, the roadway section forming effect is good, and a single cycle excavation takes 34 min, which verified the effectiveness of the cutting path design. On the basis of specific engineering geological conditions, excavation equipment and technology, combined with experimental testing, numerical simulation and other methods, the roadway excavation cutting path can be optimized, and the research results can provide a reference for the design of cutting paths for coal mine excavation roadways with the same geological conditions.

As part of a study conducted by Esso Australia investigating means of reducing the high cost of construction of submarine pipelines in Bass Strait, flexible risers connecting bottom-towed steel pipelines and the topsides of freed platforms were identified as a potential means of providing significant cost savings. To assess the concept, an extensive program of dynamic analyses and state model tests in a large wave-current flume were undertaken. This paper presents the findings of these analytical and test studies. Additional dynamic analyses were performed to assess the sensitivity of flexible riser performance to various changes in hydromechanics and other design parameters. A number of recommendations were developed for design criteria and analytical parameters for flexible riser systems, not addressed in current codes of practice for such systems. Introduction The relative remoteness of Australia from major centres of offshore oil and gas activity presents a number of problems to the viability of potential offshore field developments, notably the cost of mobilization of specialist construction vessels, such as derrick and pipelaying barges, pipe reeling vessels and diving support vessels (DSVS). In recent years Esso Australia Ltd. (EAL) has used innovative engineering and new construction techniques, minimizing or avoiding the use of such vessels altogether, to make substantial reductions in the cost of development of offshore structures and facilities in Bass Strait. Most future field developments in Bass Strait involve much smaller reservoirs than in the past, such that the high cost of conventionally installed pipelines, which has References, tables and figures at end of paper been identified as a major component of the total cost of such projects, would either preclude development or would make it a marginal proposition. In view of these considerations, EAL initiated the "Pipeline Cost Reduction Study" (PCRS), investigating novel pipelaying procedures to identify cost effective means of installing pipeline links to new marginal field developments. One of the innovations investigated in the PCRS was the use of single-catenary flexible risers as tie-ins to fixed platforms from on-bottom steel pipelines. This paper describes wave tank testing and dynamic numerical analysis of this concept, and discusses design criteria and analytical parameters for use in the design of such flexible riser systems. The following section introduces the PCRS. Section 3 develops the criteria used for the design of flexible riser systems. Section 4 describes the dynamic numerical analysis and the use of FLEXCOM-3D, while Section 5 describes the physical model studies including the effect of spectral versus regular waves and the influence of the structure. Section 6 discusses the design parameters obtained and compares the capabilities of numerical and physical models this discussion is summarised in Section 7 Conclusions. The Pipeline Cost Reduction Study and Its Application The PCRS identified a number of alternative methods of construction and new pipeline configurations which might offer substantial savings in pipeline cost. The most promising concepts were reviewed and the technical feasibility of specific aspects which offered the possibility of significant reductions in the cost of installation of the pipelines for a number of future projects were established.

Laser Induced Breakdown Spectroscopy (LIBS) for whole rock geochemistry

Mining residues, in general and metal ores, in particular, contain heavy metals within the rock. These heavy metals, including copper (Cu) for which there is an increasing demand around the world, are very harmful to humans and, as such, are a serious problem for the environment. In this study, a rhamnolipid biosurfactant was used to extract copper from an oxide residue with 8,950 mg copper per kg ore. To optimize the conditions for maximum extraction, several batch tests were performed on washed ore samples at 25°C. The best ore particle size for optimal extraction was determined to be between 0.15 and 0.3 mm while the optimal pH of the washing solution was 6. A minimum volume of 10 mL rhamnolipid of 2% concentration for 1 g of ore was required to extract about 28% of copper from the ore. Adding 1% NaOH to the biosurfactant solution dramatically improved the copper extraction from the residue up to 42% in 6 days. Unwashed samples of mixed size particles were tested under the optimized conditions and 24% of copper was extracted. A sequential extraction procedure on the residues was performed to determine the forms of copper in the ore. Although the oxide and hydroxide, residual, and carbonates are the main forms, copper was extracted mainly by the biosurfactant from the oxide and hydroxide portions.

Sand production and the sand control technique selected to mitigate or eliminate it can have a critical influence on the performance of horizontal wells in gas storage reservoirs. A completion that provides adequate sand control is usually required, but an overly conservative completion design can have an unnecessary, negative consequence on gas well productivity and injectivity. The selection of the appropriate sand control design depends on the characteristics of the reservoir formation, the in-situ stress state, the maximum and minimum values of the reservoir pressure during gas storage operations, the drawdown pressure, the near-well fluid saturations, the well trajectory and the capacity for handling sand in the well tubulars and surface facilities.This paper reviews the principal causes of sand production from borehole and perforation collapse, and demonstrates the application of commercial software programs for assessing sand production risks. The influence of formation damage, compressible and non-Darcy gas flow effects, reservoir pressure changes and rock strength reduction due to cyclic loading will be illustrated. Additional risks, such as exceeding the fracture breakdown pressure in the reservoir during injection, or collapsing weak, interbedded shale strata that are locally penetrated by the horizontal well, are also described. Numerical geomechanical modelling techniques suitable for more complex material behaviour and fluid flow phenomena are also described, as well as a novel procedure for estimating initial produced sand volumes.Several field examples are presented, illustrating results for reservoirs ranging from relatively strong rocks, in which no sand control is required, to poorly cemented sandstones which require gravel-packed or screened completions.

Conventional gravity separation process of iron mineral fines is not very effective. In present work Multi Gravity Separation (MGS) process has been studied. This study was performed on a low-grade iron ore namely goethitic- lateritic ore (GLO) from Eastern India. Detailed mineralogical, physical and chemical characteristics of a goethitic- lateritic iron ore showed that the sample contained porous and friable oxides and hydroxides of iron. The ore sample had a feed grade of 54.43% total Fe, 9.27% SiO2 and 8.02% Al2O3. Hematite and goethite are main iron-bearing minerals while kaolinite and gibbsite are the major gangue mineral constituents. Considering the characterization data, these ores were ground separately to three size fractions, namely -300 μm, -250 μm and -150 μm sizes and subjected to flowing film concentration in Wilfley Table. As revealed by the liberation study, higher concentration was obtained by the processing of -150 μm crushed sample. The grade of the ore was improved from 54.43% Fe to 65.71% Fe. However, significant amount of fine iron ore particles were lost during the processing of -150 μm size ore, because it is not very effective for particles less than 15 μm. Thus, fine hematite and goethite particles are usually not recovered resulting in the loss of valuable iron ore fines. To recover this fine, Multi Gravity Separator was used in place of Wilfley Table and was found to be effective in reducing loss of fine iron particles and increasing the grade of the concentrate. The MGS process improved the Fe from 54.43% to 66.5% along with decreasing the alumina from 8.02% to 1.17%.

Citric acid has been proved to be the most effective organic acid for nickel extraction from nickel lateritic ores. Citric acid can be produced from fungal metabolism by utilizing several types of carbon source as fungal nutrient. In the current experiment, production of metabolic citric acid from metabolism of Aspergillus niger by using corn starch as a carbon source was investigated. The application of the citric acid produced in the leaching of nickel from Indonesian saprolitic ore under atmospheric pressure was also conducted. The optimum citric acid concentration (i.e. around 0.05 M) can be produced by using 5% w/v of corn starch after 5 days incubation of A. niger, 30°C of temperature, shaker speed of 120 rpm, and 3% v/v of methanol as an additive. The metal leaching of Indonesian saprolitic ore was conducted using <75μm of ore particle size, 5% w/v of pulp density and 200 rpm of shaker speed at different leaching temperatures (30°C, 40°C, and 60°C). The results showed that the optimum nickel recovery (around 40%) can be reached after 3 days of leaching process at 40°C. It was also found that the use of metabolic citric acid was more effective for nickel leaching compared to the use of chemical citric acid at similar citric acid concentration (i.e. 0.05 M). It can be concluded that the metabolic citric acid produced from corn starch by A. niger will be an excellent leaching reagent for extracting nickel from low-grade Indonesian saprolitic ore.

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In response to the unclear drilling resistance characteristics of rocks in the Ji’yang Depression, low drilling efficiency of PDC drill bits, and difficulties in drill bit selection, this study selected rock samples from different depths in the area for indoor drilling resistance analysis testing. Based on logging data, a prediction model was established for drilling resistance characteristics parameters of the strata in the area, and a graph of drilling resistance characteristic parameters of the rocks in the area was drawn. The study showed that the uniaxial compressive strength of the strata rocks was 50–110 MPa, with a hardness of 500–1300 MPa, a plasticity coefficient ranging from 1 to 2, a rock drillability grade of 8–20, and an abrasiveness index of 5–20. Combining the analysis of on-site drilling bit failures, PDC drill bits adapted to the strata in the area were selected, and the mechanical drilling speed of the selected bits reached 12.58 m/h, successfully drilling through the target layer. The above research results are of guiding significance for understanding the reasons for the difficulty of drilling into the Jiyang Depression strata and for improving mechanical drilling speed and drill bit selection in this area.