Research on Energy Dissipation Laws of Coal Crushing under the Impact Loads

Dynamic crushing characteristics of coals are closely related with energy absorption and release of coals under certain strain rate. Hence, it is necessary to investigate energy dissipation laws of coal crushing under the impact loads with different strain rates. Based on the dynamic and static mechanical tests, crushing energy, total absorption energy, total releasable elastic latent energy, and relations between fractal feature of fragments, mean particle diameter and energy during crushing behaviors of outburst coal and nonoutburst coal were investigated. According to research results, crushing energy, total absorption energy, and releasable elastic latent energy of outburst coal and nonoutburst coal are related with strain rate, and they present exponential growths with the increase of the strain rate. However, the energy dissipation rate (ratio of crushing energy and incident energy) was basically constant at about 10%∼20%, that is, energy dissipation rate is a variable unrelated with strain rate. There is a good logarithmic relationship between the dynamic compressive strength of coals and the absorption energy density and elastic latent energy density, and dynamic comprehensive strength of coals has important impacts on energy absorption. The fractal features of coal fragments were obvious under dynamic impacts. The higher fractal dimension of fragment and the smaller mean particle diameter of experimental fragments bring the greater energy needed.

OPTIMASI DAN ESTIMASI BIAYA PENAMBANGAN DAN PENGOLAHAN BATUBARA DI PT BHUMI RANTAU ENERGI

PT Bhumi Rantau Energi (PT BRE) pada Bulan Agustus menargetkan peningkatan produktivitas dari 500 ton per jam menjadi 560 ton per jam. Untuk itu diperlukan evaluasi terhadap ketersediaan umpan, kemampuan pengolahan batubara dan pemuatan batubara produk. Belum adanya referensi biaya pada target baru untuk Pit Cendana Selatan Seam O membuat perlunya estimasi biaya, agar diketahui biaya per-ton pada penambangan batubara (coal getting) dan peremukan batubara (coal crushing). Estimasi biaya yang digunakan ada dua macam, yakni biaya kepemilikan (owning cost) dan biaya operasi (operating cost).Metode yang digunakan dalam penelitian ini adalah menghitung produktivitas aktual alat mekanis kemudian menganalisanya. Supaya mendapat hasil maksimal, maka diperlukan optimasi untuk menghasilkan target yang diinginkan. Setelah dibuat simulasi untuk kegiatan optimasinya, selanjutnya dilakukan perhitungan trial, dimana setelah trial hasilnya akan dianalisis apakah mencapai target atau tidak. Setelah kegiatan trial mencapai target, akan dilakukan perhitungan estimasi biaya pada kegiatan penambangan batubara dan peremukan batubara.Pada trial, didapatkan produktivitas alat gali muat pada fleet 1 sebesar 291,376 ton/jam dan fleet 2 sebesar 290,926 ton/jam, dengan produktivitas Pit 583,302 ton/jam. Produktivitas alat umpan pada StockROM unit WL-01 sebesar 577,949 ton/jam. Produktivitas alat gali muat pada Stockcrushed unit WL-02 sebesar 284,598 ton/jam dan pada WL-03 sebesar 284,234 ton/jam, dengan produktivitas Stockcrushed 569,832 ton/jam. Estimasi biaya pada kegiatan coal getting didapat sebesar $ 0,707/ton dan pada kegiatan peremukan batubara (coal crushing) didapat estimasi sebesar $ 0,287/ton. Kata Kunci : Optimasi, Produktivitas, Estimasi Biaya

Study on the Decoupled Charge Effect in Deep-Hole Cumulative Blasting of Coal Seam

Five models of cumulative blasting are established by using ANSYS/LS-DYNA to study the effect of decoupling coefficient on cumulative blasting to improve coal seam permeability. The formation and migration process of the shaped energy jets with two kinds of decoupling coefficient are compared and analyzed; also, the propagation of explosive stress waves is represented. The result showed that the air in the blast hole is the key to the formation and migration of the condensing jet. The air in the hole also could reduce the attenuation of stress wave in a certain range. However, if the decoupling coefficient is too large, the air in the hole will consume excessive explosive energy, which is also not conducive to energy transfer. Therefore, there is an optimum decoupling coefficient which can minimize the coal crushing area, increase the coal fissure area, and improve the gas extraction rate. Besides, the cumulative blasting tests were carried out in a coal seam. The test results show that decoupling charge could effectively improve coal seam permeability, and the blasting effect was better when the decoupling coefficient is between 1.67 and 2.

Resource-Saving Quality Management Systems of Coal Products Using the DSKA-4m Сomplexes

The article presents developed and widely implemented processing technologies of mining enterprises (crushing, classification, averaging adjustment screen composition, dehydration, loading, storage, reducing the ash content and moisture source)-based complexes DSKA. Offers innovative technical software allows mining companies and companies to create and consumers, in accordance with fluctuations in the market, to adjust flows of products providing a wide range of quality. Coal crushing and classification equipment is widely used in coal mines, sea and river ports, railway terminals and large coalstorage yards. However, drawbacks of the conventional technologies used in crushing (jaw, cone, rotary and rolling crushers), sizing (on low-frequency high-amplitude screens) and conveying (belt conveyors) worsen efficiency of production and decrease its attractiveness as investment. Besides, the preparation plants in service cannot, as a rule, ensure the integrated and adjustment-flexible approach to providing the desired quality of coal end product.

EVALUASI SISTEM BELT CONVEYOR DAN ANALISIS SISTEM CRUSHING PADA COAL CRUSHING PLANT

Kecepatan, daya, dan tegangan belt conveyor perlu dilakukan optimasi apabila terjadi masalah pada power factornya. Selain pertimbangan pada power factornya. Selain pertimbangan pada power factor, optimasi juga dilakukan atas pertimbangan produktivitas. Sistem crushing pada PT Pamapersada Nusantara ditrik KCMB saat ini dapat dilakukan perbaikan. Perbaikan tersebut dilakukan guna memaksimalkan primary crusher sebagai salah satu kompoen sistem crushing. Optimasi yang dilakukan pada sistem crushing saat ini berdasar pertimbangan aspek teknis seperti power factor dan produktivitas.Penelitian ini dilakukan pendekatan secara teoritis menggunakan referensi tentang belt conveyor. Selain itu juga menggunakan data yang secara langsung diambil dari lapangan yang kemudian guna dilakukan perhitungan dan analisa untuk ditentukan evaluasi terhadap hasil penelitian.Belt conveyor pada sistem crushing PT Pamapersada Nusantara distrik KCMB sebaiknya dilakukan optimasi guna memperbaiki nilai power factor yang kecil. Perbaikan dapat dilakukan dengan menambah daya yang tersedia pada motor penggerak pulley. Sistem crushing juga dapat dilakukan perbaikan dengan menambah komponen-komponen sistem crushing guna mengoptimalkan kinerja tiap-tiap komponen tersebut. Kata-kata kunci: Belt conveyor, power factor, optimasi, sistem crushing

Classification Prediction Method Used in Coal Crushing

Coal principal stresses with reservoir plane is analyzed, consequently coal seam crushed classification method is presented based on Hoek-Brown criterion. According to the coefficient of coal crushing, coal seam crushed coefficient size, four grades of A,B,C,D are divided for coal crushed degree along wellbore direction, and coal crushed classification standard is determined. Using the classification method and standard, the distribution regularity of coal crushing is studied for ZP-05 Well in QinShui basin. The research results show that coal crushing of ZP-05 is considered as grade B. The prediction results agree well with the measured values.