Diamond Drill Research Articles

Вплив вибору марки ріжучих алмазів та концентрації УДПА у наповнювачі зв’язки на працездатність алмазних трубчастих свердл при обробці граніту та скла

The results of laboratory tests for drilling granite and window glass with diamond tube drills are given. The drills were made by the method of vacuum impregnation, developed at the Institute of Scientific Research of the National Academy of Sciences named after I. M. Frantsevich, and studied on a Sachsenwerk drilling machine (Dresden, Germany) in cold running water in order to prevent oxidation of diamonds and bonds due to their heating during work. The dependence of the efficiency of the drills on the content of very strong cutting diamonds of the AS500 500/400 brand, less strong — of the AS32 500/400 brand, as well as on the concentration of ultradispersed diamond powders (UDPA or ASM 1/0) in the filler of the tool bundles was studied. These indicators were compared with the indicators of drills equipped with diamond grains of the AS200 500/400 brand, which were obtained and described earlier when drilling the same non-metallic materials. The performance of diamond drills was evaluated by their wear and drilling speed. The highest quality tools can be obtained if you use high-strength diamond grains of the AS500 500/400 brand. The operational characteristics of such drills differed in high wear resistance (low wear) and drilling speed. The efficiency of drilling with diamond drills that were equipped with lower-quality diamond grains of the AS200 500/400 and AS32 500/400 brands was significantly lower. It was possible to increase the drilling speed and reduce the wear of such tools when the filler was introduced into the connection with ASM 1/0 in the amount of 5—7% (wt.) due to the improvement of its mechanical properties. But all the same, such diamond drills were inferior in efficiency to tools equipped with high-quality diamonds of the AS 500 500/400 brand. Keywords: diamond drills, bond samples, drilling tests, drilling speed, wear.

An adaptive sequential sampling method based on ANN_MCD and RF: Application in geotechnical problems

In geotechnical engineering, surrogate modeling is a vital technique for enhancing computational efficiency when faced with limited and costly samples. However, most adaptive sequential sampling (ASS) methods use the Kriging model, which directly evaluates the uncertainty of the model at unsampled points, but they are not efficient in solving multiple output problems. A few studies use cross-validation to indirectly evaluate the uncertainty of other surrogate models, which is time-consuming to repeatedly train multiple models. In addition, few methods consider input feature sensitivity, which further reduces the efficiency of ASS methods. To address these issues, this study proposes a hybrid ASS method that combines artificial neural networks with Monte Carlo dropout (ANN_MCD) and random forests (RF). The ANN is suitable for multiple output problems, and the MCD enables the ANN architecture to stochastically transform and efficiently predict uncertainty at unsampled points with a single model training. The RF evaluates input feature sensitivity, assigns weights to the sampling space based on feature sensitivity, and effectively avoids the interference of low-sensitivity features. Furthermore, two active learning functions are proposed to regulate the sampling areas on either a global scale or close to the limit state function, depending on the problem type. The study validates the efficacy of the proposed method through three representative geotechnical engineering examples: system reliability analysis of soil slope, back-analysis of soil constitutive parameters, and estimating the penetration rate in diamond drilling. The outcomes demonstrate that the proposed method has less computational cost than related studies and has more potential in addressing geotechnical sampling.

Thermal drilling for application in gas and oil wells: Efficiency enhancement by acoustic inspection

Thermal drilling has recently attracted the attention of researchers due to its high efficiency in breaking hard rocks. However, the advent of low-efficiency processes, such as melting and evaporation, is challenging thermal drilling performance. The implementation of realistic guidelines to monitor spallation may help enhance the performance of this technology. In this article, the results of the continuous and intermittent application of butane oxygen flame on dry and wet limestone were compared with the results of diamond drilling based on the resulting rate of penetration and specific energies. A high-quality camera was operated as a device for visual inspection of the processes to determine any obvious macroscopic physical and chemical changes. In addition, acoustic monitoring of the processes involved during the thermal heating experiments was carried out using a microphone with a frequency response region below 20 kHz. The background noise in the recorded acoustic signals was eliminated by using noise reduction methods in MATLAB. The software performed Fast Fourier Transform (FFT) on the obtained clean signals to reveal the related frequency spectrograms. According to our experimental observations, the frequency response for spallation occurrence in wet and dry samples appears to be around 7 kHz and 15 kHz, respectively. However, the frequency response for fracture formation did not reveal a sensible dependence on moisture content in the limestone samples. Under continuous heating, the rate of penetration and the specific energy for wet samples were respectively 131% higher and 68% lower than those for the dry samples. In the dry samples, wetting between the two heating processes led to a considerable increase in the penetration rate and a dramatic decrease in the specific energy due to keeping the local temperature gradient high in the rock texture.

The world-class carbonate-hosted Fankou Zn-Pb deposit in China. Part I. Structural analysis: Evolutionary three-order thrusting structures control on the localization of Zn-Pb orebodies

The Fankou giant deposit (with exceeding 10 Mt Zn + Pb metals, grading at 15 wt%) is a carbonate-hosted, stratabound Zn-Pb deposit in the northern Quren Basin, South China. Lenticular, stratiform and wedge-shaped orebodies are strictly hosted in specific layers of Upper Devonian to Lower Carboniferous carbonate sequences along a series of NE and NNE trending faults. Previous ore geological and geochemical studies proposed that the Fankou can be analogous to a Mississippi Valley-type (MVT) deposit, but how the evolution of complex fault system controls ore-forming fluids migration, metals accumulation and orebodies localization remains unclear. To address this question, we conducted a deposit-scale structural analysis based on the geological mapping, underground works, and diamond drills logging. We identified three-order structures gradually growing in the Fankou deposit, including: 1) The first-order fault represented by F203 is a NW-striking thrust fault penetrating basement and acts as a major conduit for ultimate hydrothermal fluids migrations from depth; 2) The second-order faults include a spectrum of NNW-striking faults F2, F3, F4, F4, F5, F6, F7, F8 and F9. They are intersected with F203 in depth, and soon before and synchronous activities with Zn-Pb mineralization; 3) The third-order faults contain a series of NNE-striking F100, F101 and F102 with limited scale, which is subordinate to second-order faults and control the terminal localization of Zn-Pb orebodies. Collectively, we conclude that the evolutionary three groups of deposit-scale faults, derived from the regional NE-striking Wuchuan-Sihui Fault, jointly control the ore-forming fluids migrations from deep to shallow and from SE to NW in space. It is noteworthy that the second- to third-order faults act as the direct metal precipitation space when the upwards metalliferous fluids replaced with the favorable lithological layers. Therefore, we highlight that the southeast part of the mining area, where the metalliferous fluids came from, is a promising exploration target area in future.

Managing Quartz Exposure in Apartment Building and Infrastructure Construction Work Tasks.

The present report describes exposure to respirable silica and dust in the construction industry, as well as means to manage them. The average exposure in studied work tasks (n = 148) amounted to 64% of the Finnish OEL value of 0.05 mg/m3. While 10% of exposure estimates exceeded the OEL, the 60% percentile was well below 10% of the OEL, as was the median exposure. In other words, exposure was low in more than half of the tasks. Work tasks where exposure was low included construction cleaning, work management, installation of concrete elements, rebar laying, driving work machines equipped with cabin air intake filtration, and landscaping, in addition to some road construction tasks. Excessive exposure (>OEL) was related to not using respiratory protection at all or not using it for long enough after the dusty activity ceased. Excessive exposures were found in sandblasting, dismantling facade elements, diamond drilling, drilling hollow-core slabs, drilling with a drilling rig, priming of explosives, tiling, use of cabinless earthmoving machines, and jackhammering, regardless of whether the hammering took place in an underpressurized compartment or not. Even in these tasks, it was possible to perform the work safely, following good dust prevention measures and, when necessary, using respiratory protection suitable for the job. Furthermore, in all tasks with generally low exposure, one could be significantly exposed through the general air or by making poor choices in terms of dust control.

Overall Drilling Effectiveness: key performance indicator adapted for rock drilling

OEE (Overall Equipment Effectiveness) is a key performance indicator (KPI) widely used in performance analysis in the mining industry. The present study develops the ODE indicator (Overall Drilling Effectiveness) adapting OEE concept for the reality of diamond drilling. The product of availability, utilization and quality rates in the drilling process calculates ODE. Quality is defined by the quotient between recovered drill core metreage and total drilling advance metreage. ODE consists of a management numeric tool when confronted with productivity results and drilling equipment cost. In this case study of Pilar Mine, property of Jaguar Mining Inc., the 21% rate portrays the minimum acceptable ODE value considering the enterprise operational reality according to its geological, logistical and financial particularities. When the ODE rate approaches or exceeds this value, productivity increase and cost reduction per drilled metreage are noted. The adaptation of OEE concept and elaboration of ODE as a new performance indicator, intended directly for diamond drilling process, displays as a useful performance control tool. The utilization of ODE as a KPI provides the opportunity to manage operational productivity and financial performance simultaneously.

Pneumatic Underwater Coral-Coring Drill

Abstract To extract meter-length, large-diameter cores from live massive corals on shallow reefs we developed a versatile underwater pneumatic drill driven by a portable gasoline-powered air compressor carried onboard a small boat. This drill was used to obtain intact cores 8.0 cm in diameter and 0.5‐1.5 m long from Guam's coastal waters. Advantages of this pneumatic drill over standard hydraulic drills include (1) lower cost; (2) easier portability; (3) more stable, safer, and faster drilling; and (4) elimination of the need to carry and use hydraulic fluid on the coral reef. The pivotal innovation in the application of pneumatic technology was use of an air motor rather than a conventional handheld pneumatic drill. Another significant innovation was employment of a pneumatic water pump to provide a continuous flow that purges debris from the borehole and the cutting edge of the diamond drill bit. This drill can provide paleo-climate researchers and others interested in retrieving high-quality coral core samples with a reliable, economical, easy to operate, safe, and environmentally friendly alternative to more expensive and cumbersome hydraulic drills.

Application of the k-Prototype Clustering Approach for the Definition of Geostatistical Estimation Domains

The definition of geostatistical domains is a stage in the estimation of mineral resources, in which a sample resulting from a mining exploration process is divided into zones that show homogeneity or minimal variation in the main element of interest or mineral grade, having geological and spatial meaning. Its importance lies in the fact that the quality of the estimation techniques, and therefore, the correct quantification of the mineral resource, will improve in geostatistically stationary areas. The present study seeks to define geostatistical domains of estimation for a mineral grade, using a non-traditional approach based on the k-prototype clustering algorithm. This algorithm is based on the k-means paradigm of unsupervised machine learning, but it is exempt from the one-time restriction on numeric data. The latter is especially convenient, as it allows the incorporation of categorical variables such as geological attributes in the grouping. The case study corresponds to a hydrothermal gold deposit of high sulfidation, located in the southern zone of Peru, where estimation domains are defined from a historical record of data recovered from 131 diamond drill holes and 37 trenches. The characteristics directly involved were the gold grade (Au), silver grade (Ag), type of hydrothermal alteration, and type of mineralization. The results obtained showed that clustering with k-prototypes is an efficient approach and can be used as an alternative or complement to the traditional methodology.

Усталостная прочность сварных соединений сталей 30ХГСА–40ХМФА, полученных ротационной сваркой трением

Rotary friction welding (RFW) is used in the production of drill pipes for solid mineral prospecting. The need for the creation of the lightened drill strings for high-speed diamond drilling of ultradeep wells dictates the necessity of a greater focus on the study of a weld zone and setting the RFW technological parameters. This paper presents the results of experimental studies of a welded joint of a drill pipe of the H standard size according to ISO 10097, made of the 30ХГСА (pipe body) and 40ХМФА (tool joint) steels under the cyclic loads. The authors evaluated the influence of the force applied to the workpieces in the process of friction of the contacting surfaces (force during heating), and postweld tempering at a temperature of 550 °С on the cyclic life of welded joints, under the conditions of alternate tension-compression at the cycle amplitude stress of ±420 MPa. The study determined that with an increase in the force during heating, the microstructure changes occur in the zone of thermomechanical influence, contributing to an increase in the fatigue strength of welded joints. The authors identified the negative effect of postweld tempering on the fatigue strength of welded joints, which is expressed in the decrease in the number of cycles before failure by 15–40 %, depending on the magnitude of the force during heating. The optimal RFW mode of the specified combination of steels is determined, which provides the largest number of cycles before failure: the force during heating (at friction) Fh=120 kN, forging force Ffor=160 kN, rotational frequency during heating n=800 Rpm, and upset during heating l=8 mm. A series of fatigue tests have been carried out at various values of the cycle amplitude stress of the welded joint produced at the optimal mode and the 30ХГСА steel base metal; limited endurance curves have been plotted. It is shown that the differences in the limited endurance curves of the pipe body material (30ХГСА steel) and the welded joint are insignificant. The obtained results are supplemented by the microhardness measurement data and fractographs of fractured samples, revealing the mechanism of crack propagation under the cyclic loads.

HYDRO-MECHANICAL DRILLING OF WELLS

The solution to the problems of the construction of deep wells is possible when creating downhole tools on a fundamentally new ideological basis, involving physical principles, technical solutions unconventional in the field of drilling equipment. It is important to take into account the energy resources that increase with depth. Following this concept, based on the tasks of geological exploration, a downhole layout has been developed and introduced into the production of drilling wells, with design features and technological capabilities focused on a comprehensive solution to the problems of well wiring. Structurally, the downhole layout aimed at maximizing the potential energy of the working fluid is universal, designed for drilling wells with core sampling of increased diameter (100 mm or more), and with a solid face. In addition to the outer pipe and core receiver, the downhole layout is equipped with diamond drill heads with a stepped matrix, with a separate system of flushing channels, collectively realizing the effect of hydro-mechanical destruction of rocks. By introducing into the composition of the bottom-hole layout, converting the ascending flow into a rotational-ascending one, the problem of removing sludge from under the end of the stepped matrix is effectively solved. Production tests of the downhole layout with core sampling were carried out at the polymetals deposit of Central Kazakhstan, solid face during drilling of groundwater wells in the territory of the Almaty region. According to the results of production tests, it was found that the hydro-mechanical destruction of rocks is especially effective in combination with diamond drill heads with a stepped matrix. The presence of a turbulator-expander in the bottom-hole layout made it possible to significantly increase the amount of incoming sludge of drilled rock in the well sump, especially when drilling wells with a solid face. In comparable geological and technical conditions of drilling wells, serial core sets HQ with a drilling diameter of 95.6 mm had the following indicators: energy consumption – 2.1-2.4 kW / hour, core yield with a diameter of 63 mm – 93%, specific lumpiness of the core – 5-8 pcs / per linear meter of drilling, drilling was carried out at an axial load of 2200-2500 kgf, rotation speed 500-700 rpm. Similar indicators of the downhole layout: energy consumption – 1.2-1.5 kW / hour, core yield – 98-100% with a diameter of 112 mm, specific lumpiness – 2-3 pieces, axial load – 700-900 kgf, rotation speed – 300-400 rpm.

A new approach to solving the problems of increasing the efficiency of geothermal field development

The initial prerequisites for the effective development of geothermal deposits have been developed. Geological – reliable information about the geological structure of thermal water deposits, compositions, physical and mechanical properties of rocks in the “water-rock” system. Technical – means of well construction, design features and technological capabilities corresponding to the conditions of the mining environment, ensuring the production of highly informative geological material in the form of a core, maintaining the stability of the walls of wells from collapse and shedding. A series of diamond drill bits with a hydrojet effect of rock destruction, corresponding to the conditions of opening hot springs, have been developed and tested in practice for drilling wells. A scheme of a circulation system for the opening and development of geothermal deposits consisting of a vertically injection and an obliquely ascending well connected by a smooth bend of an intermediate shaft is proposed. The ideological novelty of the scheme, which differs from all known schemes for the development of geothermal deposits in the world, provides for the possibility of creating conditions for the manifestation of the internal energy of the earth’s interior and the thermal horizon, aimed at improving the efficiency of the development of geothermal deposits. The structural features of the scheme are that a vertical injection well lined with a filter column in the section of the thermal horizon is made with ledges, where shock waves of increased and decreased pressure are generated when water is supplied, by dividing the water flow into a central core and lateral components. As a result, the thermal horizon is affected by alternating hydraulic impulses, an increase in rock permeability and an acceleration of water inflow into the well. At the same time, by linking the borehole system with an intermediate trunk, and laying an ascending well with an obliquely cased filter column, the volume coverage of the thermal horizon is provided, increasing the uninterrupted operation period, where the circulation channel from the lower ledge to the entrance to the tank with smoothly bending joints is made with one diameter. This eliminates local pressure losses. By grinding the wall of the intermediate shaft with rock hardening, water leaks and pressure losses along the length of the circulation channel are eliminated. The significance of the circulation scheme – the extraction of hot water is carried out by forced self-discharge, without attracting energy from outside.

A drift isopach model for the southwestern Great Slave Lake region, Northwest Territories, Canada

ABSTRACT This study produced a drift thickness model for the southwestern Great Slave Lake area of northern Canada, using 12,692 lithostratigraphic records (seismic shothole drillers’ logs, diamond drill holes, petroleum wells), and field observations. Numerous algorithms and modelling parameters were tested using 6122 records of absolute drift thickness, and based on a cross-validation analysis, an empirical Bayesian kriging K-Bessel detrended algorithm was found to produce the best fit. The final model, incorporating selected maximum and minimum thickness estimate data, produced a root mean square error of 4.98 m, with 94.8% of the data points within ±2 m of the modelled drift thicknesses. The model identifies widespread areas of drift >10 m thick, and prominent southeast-northwest aligned bedrock ramps. Karst structures buried by ≤73 m of drift were identified southwest of Great Slave Lake and appear to be aligned with regional fault systems like ore-associated karst at Pine Point. These may be the source of anomalous glacial sediment-derived base metal indicators collected proximally to the west. The most striking drift anomaly is in Cameron Hills where the eastern and northern margins are comprised of shale and siltstone bedrock overlain by 20–40 m of glacial sediments, but the central and western uplands have petroleum well logs identifying glacial sediments up to 400 m thick. In addition to mineral exploration, results of this study provide baseline data that can be used predictively by the petroleum industry in designing future seismic and drilling (casing depth) operations, and by those modelling groundwater sources and flow.

Design of diamond drill heads with a hydrojet effect of rock destruction

It follows from the analysis of materials related to the design and operation of drilling equipment that an important direction in the search for effective solutions appears to be the improvement of the structure of the working matrix of diamond drilling heads and the enhancement of their technological capabilities by using in their schemes physical effects that are unconventional in the field of well drilling technology. The tasks to be solved are to reduce the energy costs of the process of deepening wells, to obtain a structurally integral, informative core, and to ensure the stability of well walls. Following the concept, diamond drill heads with a separate system of washing channels and a hydrojet effect of rock destruction were designed and tested during the drilling of wells. The novelty of the structure of drill heads is the direction of the pressure flow of liquid to the steps of the bottom of the wells, repeating the shape of the matrix, the removal of sludge along the grooves and radial grooves, the treatment of the well wall. A special technology for the manufacture of diamond drill heads with a complex geometry of the matrix has been devised. The performance of diamond drill heads of various designs was tested under the industrial conditions of drilling wells for water and at polymetal deposits. It has been established that in terms of the quality of the tasks to be solved and technical and economic indicators, they have a significant advantage in comparison with standard equipment in terms of the mechanical speed of drilling wells, energy costs, and structural integrity of the core. The comparative states of the shape, the transverse size of the hydrogeological well, the purity of the treatment of the wall of the latter, drilled by diamond drill heads and standard equipment with ball bits, are indicative. The structural integrity of the core selected by the regular column set HQ in an assembly with drill heads with a hydrojet effect of rock destruction is ensured

Artificial intelligence-based anomaly detection of the Assen iron deposit in South Africa using remote sensing data from the Landsat-8 Operational Land Imager

Most known mineral deposits were discovered by accident using expensive, time-consuming, and knowledge-based methods such as stream sediment geochemical data, diamond drilling, reconnaissance geochemical and geophysical surveys, and/or remote sensing. Recent years have seen a decrease in the number of newly discovered mineral deposits and a rise in demand for critical raw materials, prompting exploration geologists to seek more efficient and inventive ways for processing various data types at different phases of mineral exploration. Remote sensing is one of the most sought-after tools for early-phase mineral prospecting because of its broad coverage and low cost. Remote sensing images from satellites are publicly available and can be utilised for lithological mapping and mineral exploitation. In this study, we extend an artificial intelligence-based, unsupervised anomaly detection method to identify iron deposit occurrence using Landsat-8 Operational Land Imager (OLI) satellite imagery and machine learning. The novelty in our method includes: (1) knowledge-guided and unsupervised anomaly detection that does not assume any specific anomaly signatures; (2) detection of anomalies occurs only in the variable domain; and (3) a choice of a range of machine learning algorithms to balance between explain-ability and performance. Our new unsupervised method detects anomalies through three successive stages, namely (a) stage I – acquisition of satellite imagery, data processing and selection of bands, (b) stage II – predictive modelling and anomaly detection, and (c) stage III – construction of anomaly maps and analysis. In this study, the new method was tested over the Assen iron deposit in the Transvaal Supergroup (South Africa). It detected both the known areas of the Assen iron deposit and additional deposit occurrence features around the Assen iron mine that were not known. To summarise the anomalies in the area, principal component analysis was used on the reconstruction errors across all modelled bands. Our method enhanced the Assen deposit as an anomaly and attenuated the background, including anthropogenic structural anomalies, which resulted in substantially improved visual contrast and delineation of the iron deposit relative to the background. The results demonstrate the robustness of the proposed unsupervised anomaly detection method, and it could be useful for the delineation of mineral exploration targets. In particular, the method will be useful in areas where no data labels exist regarding the existence or specific spectral signatures of anomalies, such as mineral deposits under greenfield exploration.

A method to indicate heavy minerals in logging-while-drilling

The low-energy region of the gamma ray spectrum, less than 200 keV, often is either discarded or not analyzed in borehole logging or airborne radiometric surveys. There is much useful information about earth properties to be extracted from the low-energy region because it is sensitive to photoelectric absorption within the rock, a process that is highly sensitive to the atomic number of the elements within the rock. In addition, the rate of photoelectric absorption is proportional to the density of the rock. At higher energies, the spectrum is primarily sensitive to density variations only. The ratio of counts in the two energy regions may be used as a heavy mineral indicator (HMI). This ratio normalizes density effects and is primarily sensitive to variations in the average (or effective) atomic number ([Formula: see text]) of the rock. Previous work by other authors has focused on the application of this idea for wireline logging with an isotopic source and multiple scattering of copious primary gamma rays, which allows for good counting statistics in the recorded spectrum. Recent advances in gamma ray detectors and logging-while-drilling (LWD) techniques open the possibility of applying the HMI measurement to the natural gamma ray LWD logs. Drilling speeds are much slower than the running speeds of wireline tools, resulting in improved counting statistics. Using computer simulations, laboratory experiments, and field measurements, we find that the natural gamma ray spectrum, recorded while (diamond) drilling, provides sufficient counting statistics to be used for robustly calculating HMI. As iron is the most abundant and influential element in photoelectric gamma ray scattering processes in rock fabrics, we postulate that we can, in most cases, use HMI to indicate the iron content of the rocks. The HMI calculated under these conditions provides a good measure of changes in [Formula: see text] of rocks and correlates well with iron-rich sections. Our field and laboratory tests demonstrate that the HMI measures can be used as a proxy to separate many metalliferous ores from waste based on the differences in [Formula: see text].

Effect of dental tissue thickness on the measurement of oxygen saturation by two different pulse oximeters.

This study aimed to evaluate the influence of different dental tissue thickness on the measurement of oxygen saturation (SpO2) levels in high (HP) and low (LP) blood perfusion by comparing the values obtained from two different pulse oximeters (POs) - BCI and Sense 10. Thirty freshly extracted human teeth had their crowns interposed between the POs and an optical simulator, which emulated the SpO2 and heart beats per minute (bpm) at HP (100% SpO2/75 bpm) and LP (86% SpO2/75 bpm) modes. Afterwards, the palatine/lingual surfaces of the dental crowns were worn with diamond drills. The reading of SpO2 was performed again using the POs alternately through the buccal surface of each dental crown. Data were analyzed by the Wilcoxon, Mann-Whitney and Kendall Tau-b tests (α=5%). The results showed significant difference at the HP and LP modes in the SpO2 readouts through the different dental thicknesses with the use of BCI, and at the LP mode with the use of Sense 10, which had a significant linear correlation (p<0.0001) and lower SpO2 readout values in relation to the increase of the dental thickness. Irrespective of tooth thickness, Sense 10 had significantly higher readout values (p<0.0001) than BCI at both perfusion modes. The interposition of different thicknesses of enamel and dentin influenced the POs measurement of SpO2, specially at the low perfusion mode. The POs were more accurate in SpO2 measurement when simulated perfusion levels were higher.

SVM MODEL FOR PREDICTION OF ELECTROCHEMICAL DIAMOND DRILLING RESPONSE PARAMETERS

Machining of advanced materials is difficult with traditional machining methods so the development of new and hybrid nontraditional machining processes is being done. These hybrid processes have complex machining process parameters and optimization of these is very necessary for better machining characteristics. Here a Support Vector Machine model is utilized to develop a prediction model for electrochemical diamond drilling process. The prediction accuracy achieved with SVM model was better than the developed quadratic regression model.

EFFECT OF MECHANICAL AND TRIBOLOGICAL PROPERTIES OF DIAMOND FILMS ON VARIOUS SUBSTRATES

Geological drilling required high-performance diamond drill bits. In this paper, diamond films were deposited on different drill bit substrates based on the MPCVD equipment. The properties of diamond films were analyzed by scanning electron microscopy (SEM), Raman spectra, X-ray diffraction (XRD) and tribological tests. The results showed that surface morphology of the four different substrates was good and the grain size was uniform. The diamond drill bit substrates include polycrystalline diamond compact (PDC), cemented carbide (WC–Co), impregnated diamond (IPD) and diamond thick-film welded (DT) sheets. The coefficients of friction of the deposited protective films are 0.15, 0.25, 0.23 and 0.29, respectively. What is more, the wear rates of protective films are [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text][Formula: see text]mm3/N[Formula: see text]m, respectively. Addition of diamond films could effectively reduce the friction coefficient on the surface and improve the service life of drill bit.

Sampling of high-nugget conglomerates from the Western Australian Pilbara: bulk sampling at the Beatons Creek gold project, Nullagine

Many styles of gold mineralisation pose challenges during sampling because of the presence of coarse gold and high natural heterogeneity (“nugget effect”). The gold-bearing conglomerates of the Western Australian Pilbara provide some challenges. Novo Resources Corporation has addressed many of these over the last five years. Its Beatons Creek open pit operation is the first Pilbara conglomerate to go into production (January 2021) based on a total oxide Mineral Resource of 316,000 oz Au (5.2 Mt at 1.9 g/t Au at a 0.5 g/t Au cut-off). Mineralisation occurs within the Beatons Creek conglomerate member of the Hardey Sandstone formation, which constitutes part of the Fortescue Group. Gold is present within the matrix of multiple, narrow stacked and un-classified ferruginous-conglomeritic reef horizons, which are interbedded with un-mineralised conglomerate, sandstones and grits with minor intercalations of shale, mudstone, siltstone and tuffs. The gold occurs as free particles up to 5 mm across within the ferruginous matrix of the conglomerates. It is closely associated with detrital pyrite and authigenic nodules. Previous owners and Novo have employed several sampling techniques across the project including diamond and RC drilling, trench channel sampling and bulk sampling. Assay methods included fire assay, LeachWELL and more recently PhotonAssay. As part of its 2018 evaluation programme, fifty-eight c. 1-4 t bulk samples were collected from accessible oxide mineralisation and processed via a pilot plant. This paper presents some of the issues and solutions applied by Novo, which have wider implications and impact on the sampling of other heterogeneous orebodies.

A comparison between conventional blast hole sampling and diamond core drilling for copper grade at the Antapaccay mine

Even though the sampling technique result in potentially biased samples with poor precision of the metal grade and are classified as specimens and not samples, the manual sampling of rotary percussion blast hole chips is still widely performed in the industry for operational grade control purposes. The objectives of this investigation are to estimate the precision and“bias” of manual sampling by comparing the copper grade results of fifteen (15) diamond drill core samples versus fifteen (15) rotary percussion blast hole drilling chip samples. This also includes the determination of a practical manual sampling template with the highest precision to providean understanding of the distribution of the copper content within the cone of blast hole chips. The contouring plots of thecopper grades provides the selection of the best fit-for-purpose template with regards precision and operational resourcing requirements. The diamond drill core samples take into account the Increment Delimitation Error (IDE) andIncrement Extraction Error (IEE) and therefore can be considered as reference samples for the purpose of this review.