Product Development of a Rock Reinforcing Bolt for Underground Hard Rock Mining

The demand for mineral resources has dramatically increased over the past few decades; this increase directly correlates to an increase in underground mining activity. There are different mining methods for different minerals, and each have their risks. In hard rock mining activities such as mining for gold, rockfalls are the most significant deterrent to obtaining mineral resources. This paper focuses on rock reinforcement systems to prevent fatal rockfalls in underground excavations. Presently, there is a global steel shortage and an increase in prices that has impacted the productivity of the mining operations that support most national economies. The paper’s main objective is to present the improvement of a rock bolt design used to support the roof in underground mining activities and keep working personnel and equipment safe from rockfalls. This study presents two rock bolt designs: a preliminary design and an improved model of the rock bolt. The paper discusses the operation of the rock bolt and provides laboratory test results on the bolt in operation. The principle of operation of the yield bolt is based on the science of radial expansion of hollow tubes in tension, to provide integrity to underground excavations. This functional design of the rock bolt requires less steel and has the same performance as the current rock reinforcement elongates. The research methodology involved interviewing rock mining engineers to determine their desired rock reinforcement device that would adequately meet the unpredictable dynamic and static behavior of underground rocks. The methodology also included experimental tests of a rock bolt design that was aimed at meeting the desired and acceptable performance determined from the interviews. The experimental results were obtained from a 60-ton hydraulic press that simulated seismic activity underground. The experimental results showed several modes of failure for the bolt; however, the improved rock bolt yielded at an average of 200 KN, as designed. During testing of the preliminary bolt design, there were failures that resulted from the manufacturing process of the bolt, such as splitting of the tube due to the welded end components. After a dynamic test, the preliminary bolt tube bent, creating huge forces on the tube which may cause fracture. The coefficient of friction during dynamic testing was lower than during static testing, leading to undesirable results for the preliminary bolt. The optimized bolt design addressed the failures and the low yield tonnage of the preliminary bolt design. It successfully yielded at 20 tons, even during the dynamic event. The bolt had similar alignment issues which caused failure during testing, as can be seen from the results. A guide tube was implemented in the design and the manufacturing process changed; these changes resulted in the bolt having a more reliable performance that met the requirements throughout.

A resource efficient and environmentally safe charge structure for mining in an open-pit

Purpose. The purpose is to reduce mineral losses during the explosive destruction of rocks and environmental pollution by harmful gases and fine particulate matter. Methods. To achieve the objectives of the study, methods of physicochemical analysis and mechanics of continuous media have been used. The method of physico-chemical analysis has been used to determine the quantitative and qualitative characteristics of the composition of the well stemming depending on the parameters of the well, the type of explosive, the amount and type of harmful gases formed during the explosion. Methods of solid medium mechanics have been used to establish the patterns of pressure waves during an explosion depending on the characteristics of the gap filler between the charge and the well wall. To solve the problem of the behavior of a two-layer medium during the loading of a cylindrical cavity by a nonstationary load, a numerical method based on the finite-difference McCormack predictor-corrector scheme has been used. Findings. A resource-saving and environmentally friendly charge structure for rock mining by explosion was developed. The design of the charge involves the formation of a gap between the charge and the wall of the borehole, and filling it with a suspension of calcium hydroxide or a suspension of calcium carbonate. Originality. SThe dependences of the volume of harmful gases (NO2, CO2, CO) formed during the explosive destruction of rocks and the magnitude of the pressure peak in the area close to the charge on the chemical composition of the filler of the radial gap between the charge and the well wall have been set. Practical implications. Developed charge design allows to neutralize the harmful gases formed during the explosion, to reduce the pressure peak in the area of the rock massif close to the charge, and can be widely used in non-metallic quarries that extract minerals for the production of crushed stone.

Conical picks of mining machines with increased utility properties – selected construction and technological aspects

Shearers and roadheaders are commonly used to extract useful mineral deposits, especially hard coal, and for drilling roadways in underground mines, tunnels and other underground buildings in civil engineering. As the primary working process of this type of machines, mechanical mining of rocks is carried out by cutting. These machines' working units are equipped for this purpose with picks, usually conical (point-attack). They have the form of an axially symmetrical body consisting of a steel shaft and a tip usually made of tungsten carbide, connected by a hard brass solder. Due to the possibility of spontaneous rotation in the pick holders and even wear and tear of their tip around the entire perimeter, conical picks have a much longer service life compared to radial picks. Their life, especially when cutting hard and sharp abrasive rocks, is, however, still unsatisfactory. Rapid wear of the picks leads to a decrease in mining efficiency, an increase in this process's energy consumption, and an increase in dynamic surplus to which the cutting machine is subject. Among many forms of wear and tear of the conical picks, attention was paid to the problem of asymmetrical abrasive wear of the tips, pulling out the connection of the soldered pick tip and fatigue breaking of the pick shafts in the transition zone of the shank into the shoulder. The article presents original propositions of modification of the construction of the roadheaders/shearers conical pick shafts and the method of fixing the tip in the pick shaft in order to increase their operational durability significantly. The technologies and devices necessary to manufacture conical picks of the proposed structure were described. The developed modifications significantly contribute to the improvement of functional properties, including the reliability of conical picks, used in particular for hard rock mining.

Diversity of Coral Genus Scleractinia in Tidung Island Waters, Seribu Islands, DKI Jakarta Province

Coral reefs are one of the most productive and diverse ecosystems on earth and provide ecosystem services. One of the islands of the Seribu Islands that has a coral reef ecosystem is Tidung Island. It is strategic and developing location makes this island used as a residential area, conservation area, and tourist destination. But the utilization has an impact on the damage of coral reefs through environmental and anthropogenic pressures. This study aims to determine coral diversity by identifying the coral genus Scleractinia and the factors that affect coral diversity. Observations were done on three different stations include 2 snorkeling areas and 1 natural area. The method used is LIT (Line Intercept Transect) and coral genus identification with Coral Finder Toolkit Indo Pacific 3.0. The results of identification obtained 16 coral genera namely genus Acropora, Montipora, Isopora, Favites, Leptastrea, Favia, Goniastrea, Montastrea, Platygyra, Echinopora, Porites, Pocillopora, Stylophora, Ctenactis, Pavona, dan Symphyllia, with the value of Diversity Index (H') in the waters of Tidung Island ranges from 0.94 – 2.34 in the category of low to moderate diversity. The parameters of water quality in Tidung Island, temperature, salinity, and acidity (pH) are relatively good for coral growth, but brightness is still relatively poor for coral growth. The impact of human activities such as snorkeling, ship anchors, fishing with destroyers, oil and waste pollution, and rock mining are factors that affect coral growth and diversity.Keywords: Coral Scleractinia; Limiting Factors; Coral Finder; Tidung IslandAbstrakTerumbu karang adalah salah satu ekosistem yang paling produktif dan beragam di bumi serta menyediakan jasa ekosistem. Salah satu pulau dari gugusan Kepulauan Seribu yang memiliki ekosistem terumbu karang yaitu Pulau Tidung. Letaknya yang strategis dan berkembang menjadikan pulau ini dimanfaatkan sebagai kawasan permukiman, daerah konservasi, dan kawasan tujuan wisata. Namun dari pemanfaatan tersebut memberikan dampak terhadap kerusakan pada terumbu karang melalui tekanan-tekanan lingkungan maupun antropogenik. Penelitian ini bertujuan untuk mengetahui keanekaragaman karang dengan mengidentifikasi genus karang Scleractinia dan faktor yang mempengaruhi keanekaragaman karang. Pengamatan di tiga stasiun berbeda yaitu di antaranya 2 kawasan wisata snorkeling, dan 1 kawasan yang masih alami. Metode yang digunakan yaitu LIT (Line Intercept Transect) dan identifikasi genus karang dengan Coral Finder Toolkit Indo Pasific 3.0. Hasil identifikasi didapatkan 16 genus karang yaitu genus Acropora, Montipora, Isopora, Favites, Leptastrea, Favia, Goniastrea, Montastrea, Platygyra, Echinopora, Porites, Pocillopora, Stylophora, Ctenactis, Pavona, dan Symphyllia, dengan nilai Indeks Keanekaragaman (H’) di perairan Pulau Tidung berkisar 0,94 – 2,34 berada pada kategori keanekaragaman rendah hingga sedang. Parameter kualitas perairan di Pulau Tidung, suhu, salinitas, dan derajat keasaman (pH) tergolong baik bagi pertumbuhan karang, namun kecerahan masih tergolong kurang baik bagi pertumbuhan karang. Dampak aktivitas manusia seperti snorkeling, jangkar kapal, penangkapan ikan dengan alat perusak, pencemaran minyak dan sampah, serta penambangan batu karang menjadi faktor yang mempengaruhi pertumbuhan dan keanekaragaman karang.

Analisis Respon Masyarakat Terhadap Dampak Aktivitas Penambangan Pasir Dan Batu Di Sungai Berni Desa Sumberasri kecamatan Nglegok Kabupaten Blitar

ABSTRACTSand and stone mining activities along the Berni River in Sumberasri Village, Nglegok District, Blitar Regency are still ongoing, so that the impact on the community is increasingly being felt. The real impact felt by the community is landslides and erosion. The purpose of this study was to analyze the community's response to the impact of sand and rock mining activities in the Berni River, Sumberasri Village, Nglegok District, Blitar Regency. The method used is a survey by conducting interviews with 40 residents who live around the Berni River, Sumberasri Village, Nglegok District, Blitar Regency. Based on the data analysis that has been carried out and explained, most of the people living around the mining area are not disturbed by mining activities because sand and rock mining is their main livelihood. There are 80% of people living in mining areas who admit that mining activities do not interfere with their activities, 90% of people who live in mining areas admit that their health is not disturbed, and 80% of people who live in mining areas admit that they have benefited from sand and rock mining activities. the. However, they all realized that the mining of sand and rock was causing losses, namely that more roads were damaged and erosion and landslides were frequent. Keywords: Mine, Sand and Stone. ABSTRAKAktivitas penambangan pasir dan batu di sepanjang Sungai Berni di Desa Sumberasri, Kecamatan Nglegok, Kabupaten Blitar masih berlangsung sampai saat ini, sehingga dampak di masyarakat semakin dirasakan. Dampak nyata yang dirasakan masyarakat adalah longsor dan erosi. Tujuan dari penelitian ini adalah untuk menganalisis respon masyarakat terhadap dampak aktivitas penambangan pasir dan batu di Sungai Berni, Desa Sumberasri, Kecamatan Nglegok, Kabupaten Blitar. Metode yang digunakan adalah survei dengan melakukan wawancara terhadap 40 warga yang tinggal di sekitar Sungai Berni, Desa Sumberasri, Kecamatan Nglegok, Kabupaten Blitar. Berdasarkan analisis data yang telah dilakukan dan dijelaskan, sebagian besar masyarakat yang tinggal di sekitar area pertambangan tidak mendapat gangguan akibat aktivitas penambangan karena penambangan pasir dan batu tersebut merupakan mata pencaharian utama mereka. Terdapat 80% masyarakat yang tinggal di area pertambangan mengakui bahwa aktivitas penambangan tidak mengganggu aktivitas mereka, 90% masyarakat yang tinggal di area pertambangan mengakui bahwa kesehatan tidak terganggu, dan 80% masyarakat yang tinggal di area pertambangan mengaku mendapat manfaat dari kegiatan penambangan pasir dan batu tersebut. Namun, mereka semua menyadari bahwa penambangan pasir dan batu tersebut menyebabkan kerugian, yaitu semakin banyak jalan yang rusak serta sering terjadi erosi dan longsor. Kata kunci: Tambang, Pasir dan Batu.

Hard Rock Mining Using Disk Tools Supported by High-Pressure Water Jets in the Aspect of Reducing Energy Consumption

The mining of hard rocks by mechanical methods, using cutting tools, is associated with problems such as sparking, dust generation and increased wear. The application of disk tools allows limiting these problems but requires constructing a machine with large dimensions and weight. To limit these problems, high-pressure water jets can be applied. The article presents the effects of using this solution in the field and stand tests when mining rocks with a symmetrical disk. The results of the bench tests of high-pressure water jets to support the process of mining with symmetrical disks, carried out at the AGH University of Science and Technology, performed on a unique test stand, which enabled the samples to be mined in a circular trajectory in conditions similar to real ones, are presented. With the use of a dimensional analysis, a theoretical-empirical model was developed to estimate the impact of slots cut by water jets on the tool load and the amount of output as a function of slots spacing and depth. Considering the similarity criteria for the mined rock sample (mechanical properties), it is possible, with the use of this model, to estimate the most advantageous working parameters while hydromechanical mining uses disks on a larger cutting radius.

Critical, Strategic and Deficit Raw Materials in the Waste of Electrical and Electronic Equipment and in Batteries and Accumulators

This article presents the waste electrical and electronic equipment and batteries and accumulators as a potential source of critical,strategic and deficit raw materials.The dominant types of waste obtained after the disassembly of used electrical and electronic equipment are plastics: polypropylene(PP), acrylonitrile-butadiene-styrene (ABS), polystyrene (PS) and teflon and metals. These metals include: magnesium, cobalt,antimony and tantalum (critical raw materials), aluminum, nickel, iron and zinc (strategic raw materials) as well as copper andsilver (deficit resources), as well as lead, tin, gold and cadmium. Batteries and accumulators are a source, among others metalssuch as: nickel and zinc (strategic raw materials), manganese and lithium (deficit resources), aluminum (strategic raw material),and cadmium, lead.The article presents the results of analysis of the material composition of the waste electrical and electronic equipment conducted atthe Institute of Mechanised Construction and Rock Mining. It also presents the level of imports and exports of waste and scrap-metalthat are the subject of this article. In addition, the article presents a source of information about waste and recycled materials.