PENGARUH KOMPOSISI CAMPURAN BATU BARA LOKAL DAN IMPOR TERHADAP KUALITAS KOKAS PT ABC

Kokas merupakan hasil karbonisasi batu bara tanpa kontak udara yang menyebabkan berkurangnya kandungan zat terbang pada batu bara sehingga nilai karbon tertambatnya menjadi meningkat. Kokas digunakan sebagai bahan bakar dan bahan pereduksi besi dalam proses pembuatan baja dalam teknologi blast furnace. Kokas yang digunakan harus memenuhi parameter kimia dan fisik yang dipersyaratkan karena memiliki peranan penting dalam meningkatkan produktifitas pembuatan baja. Parameter kimia yang dibutuhkan pada kokas yaitu nilai kadar air, kadar zat terbang, kadar abu, kadar karbon tertambat, sedangkan untuk pengujian kualitas kokas didasarkan pada dua indek degradasi yaitu CRI (coke reaction index) dan CSR (coke strength after reaction). Tidak semua batu bara lokal memiliki kualitas yang memenuhi parameter yang dipersyaratkan, seperti batu bara Adaro dan Marunda Graha Mineral (MGM) dari Kalimantan yang memiliki kualitas dibawah standar yang dipersyaratkan. Penelitian ini bertujuan untuk mendapatkan batu bara sesuai dengan standar yang dipersyaratkan PT ABC melalui pencampuran atau blending batu bara lokal dengan batu bara impor German Creek 8 (GC-8) dan Moranbah North (MN) yang memiliki kualitas yang lebih bagus. Proses karbonisasi dilakukan pada suhu 1000ºC selama 1 jam dalam suatu tungku. Variasi komposisi yang dilakukan sebanyak tiga variasi. Selanjutnya kokas hasil karbonisasi dilakukan pengujian. Dari beberapa parameter kualitas kokas yang dipersyaratkan oleh PT ABC didapat hasil kadar air ketiga variasi sampel masih memiliki kadar air yang dipersyaratkan yaitu dibawah 4%, Kadar zat terbang ketiga variasi sampel masih memenuhi nilai yang dipersyaratkan yaitu

Simulation of Coke Quality Indicators Using Artificial Neural Network

The article shows the application of a neural network for modeling coke quality indicators Coke Reactivity Index (CRI) and Coke Strength after Reaction (CSR). Two optimization methods were used to train the neural network. The influence of the number of neurons on the simulation results was studied. The difference between experimental and calculated data on average does not exceed 2 %. The conclusion is made about the prospects of using a neural network to predict the values of CRI and CSR of coke. Keywords: artificial neural network, coke, coke reactivity index, coke strength after reaction

Protective mechanism of unburned pulverized coal to coke in blast furnace

The edge and internal morphology of coke with different contents of UPC (unburned pulverized coal) after reaction with CO2 were analyzed by SEM. The influence of UPC on CRI (coke reactivity)?CSR (coke strength after reaction) and apparent porosity was also studied. The synthetic weighted mark method was used to analyze the comprehensive effect of UPC content on coke quality. The results show that because of the decrease of the content of intermediates Cf(O) and C(O)Cf(O) the restrictive step between the coke and CO2 is an interfacial chemical reaction, and it accords with the Mckewan equation 1-(1-?)1/3=kt. The UPC has a strong effect on coke when the content of UPC is 10~20%; meanwhile , the CRI and the apparent porosity are significantly decreased by 6.8% and 9.5%, respectively, and the CSR is significantly increased by 3.8%. The UPC can effectively reduce the effect of CO2 on the edge and the internal erosion of coke; the large pores and the pulverization of coke were avoided. The results of the synthetic weighted mark method showed that the comprehensive quality of coke changed greatly when the content of unburned pulverized coal was 11.24~20.87%, which is in agreement with the experimental results.

Effects of alkali metal on solution loss and coke degradation

To research the effect of alkali metals on the solution-loss rate and coke strength after reaction, potassium and sodium vapors were prepared by a high-temperature thermal-reduction method, and the thermal properties of four industrial cokes that absorbed potassium and sodium vapor were studied. The thermal properties include the traditional thermal-property indices, coke reactive index and coke strength after reaction, and the coke strength after a 25% mass loss, which is obtained by a continuous thermogravimetric test. Results show that because of the different adsorption mode, the catalytic effect of potassium and sodium is different. During the early stages of the solution-loss reaction, the reaction rate of the potassium-rich coke is higher than that of the sodium-rich coke, but the reaction rate decreases rapidly. The reaction rate of the sodium-rich coke in the later stage of the reaction is higher than that of the potassium-rich coke. The coke strength after reaction of the alkali-rich coke is low, mainly because of the high carbon-solution loss. The coke strength after the 25% mass loss of potassium-rich coke was higher than that of the original coke because the solution reaction was closer to the surface reaction.

Real-time indices focus on slag flowability and coke strength for blast furnace operation

It was well known that abnormal burden quality has a significant impact on the blast furnace (BF) permeability resulting in bad slag flowability and HM tapping, and the coke fines inside BF become much finer to reduce HM production and BF life when the coke strength is weak. Therefore, it is necessary to develop the real-time operation indices of the slag flowability and coke strength after reaction (CSR) in a lower part of BF. BF slag flowability was determined with liquidus temperature and viscosity from measured semi-synthetic slags (SiO2-Al2O3-CaO-MgO-TiO2), and the effects of MgO content, Al2O3 content and CaO/SiO2 on slag flowability are investigated according to the model equations derived from above measured data by using multiple-regression method. A real-time index combined with viscosity and liquidus temperature has been also designed to indicate appropriate slag flowability. In addition, a coke sampler was used to collect the coke samples at tuyere level to analyze the strength of BF bosh coke at various HM productivities. CSR quantitative target and its online index were obtained from the data of sampling coke properties, BF operation conditions and BF permeability to provide real-time reference for coke and HM production.