矿物质对焦炭强度的影响

选取9种金属氧化物按干煤量0.5%、1%、3%、5%添加到马钢配煤、芦岭煤、古交煤中炼成坩埚焦后,测定焦炭的显微强度、结构强度、焦炭反应性。结果表明:PbO、B2O3、V2O5使焦炭强度显著下降;SiO2、TiO2使焦炭强度略微下降;MnO2、Al2O3、CuO、ZnO对焦炭强度无明显影响。过渡金属对焦炭反应性起正催化作用,硼族元素对焦炭反应性起负催化作用。     

Treatment of metallurgical coke with an aqueous solution of sodium tetraborate

The effect of the out-of-furnace treatment of metallurgical coke with aqueous solutions of inorganic substances on changes in the coke reactivity index (CRI) and coke strength after reaction (CSR) was studied. It was found that the treatment of coke with an aqueous solution of sodium tetraborate (Na₂B₄O₇ · 5H₂O) exerted the greatest effect on an improvement in the qualitative characteristics (CRI and CSR). Changes in the values of CRI and CSR of metallurgical coke as functions of the concentration and amount of the solution of sodium tetraborate were studied. It was found that the greatest improvement in the values of CRI and CSR of coke was reached upon treatment with a 7.5% solution of Na₂B₄O₇ using 45 l per ton of coke. In this case, the coke hot strength increased by 18.8 rel %, whereas the reactivity index decreased by 13.2 rel %.     

升温速率及反应温度对焦炭反应性及反应后强度的影响

针对焦炭反应性及反应后强度测试规范性强,测试误差也较大的问题,探索了升温速率及反应温度对焦炭反应性及反应后强度的影响。实验结果表明,随着升温速率的不断的增大,焦炭的反应性在不断的减少,焦炭的反应后强度在不断的增大;小范围改变反应温度,仍对焦炭反应性及反应后强度产生比较显著的影响。升温速率越快,反应初期焦粒内部的温度低于1100℃的幅度就越大,即反应初期焦粒内部在低于1100℃条件下与二氧化碳反应的时间就越长。     

Influence of the reactivity of coke on blast-furnace performance

The cold strength M ₂₅₍₄₀₎ and M ₁₀ of the coke determines the gas permeability of the batch bed in the blast furnace down to the viscoplastic zone of the ore and the coke windows in that zone. The hot characteristics CRI and CSR determine the mechanical strength of the coke in the lower part of the furnace batch, in and below the viscoplastic zone, including the furnace well. It is wrong to regard the hot and cold characteristics as alternatives, since they describe different conditions; the significance of each one should be acknowledged. The coke consumption may be reduced with increase in reactivity of the coke, so long as the high initial strength of the coke is maintained. The minimum permissible reactivity of the coke without clogging of the hearth depends on the operating conditions in the specific blast furnace.     

Post-reaction strength of coke under various conditions

The post-reaction strength of coke was studied at different reaction temperatures in CO₂ and mixed gas atmospheres. The influence of solution loss conditions on post-reaction strength of coke, with different levels of reactivity, was studied in this paper.     

Effect of mechanochemical treatment on petroleum coke-CO2 gasification

The effect of mechanochemical treatment during the grinding of petroleum coke on its gasification by CO₂ was studied. An additive derived by drying the black liquor in papermaking industry is adopted in grinding process. Results show that the gasification reactivity of petroleum coke is effectively improved by grinding, and the activation by wet grinding is more noticeable than that by dry grinding. Besides, by wet grinding petroleum coke and additive together, the active metal species in additive are not easily volatilized in gasification, and retain a high catalytic reactivity to the coke-CO₂ reaction throughout most of the conversion range. Changes in crystal structure of the petroleum coke induced by mechanochemical treatment is related to its gasification reactivity. In general, the crystalline-amorphous phase transition is the tendency of long time mechanical grinding, while a crystal structure re-formation stage is observed after wet grinding of petroleum coke with and without additive for some time. Similar phenomenon has also been found in the reported data, but not given attention. Some discussion is made in the paper, and more work should be undertaken to disclose the mechanism.     

A new coke-slaking procedure

A method of simultaneous coke cooling and classification is described. The method consists of two stages: (1) dry cooling from about 1000 to 650°C; (2) water-jet cooling in drums from 650 to around 200°C. At the same time, coke of size class <25 mm is isolated and stabilized. The coke may be divided into two size classes. There is no need for a separate sorting structure. The coke is characterized by high strength and by low and constant moisture content; it does not break down to dust.     

Effect of boron trioxide on coke’s inner carbon solution loss reaction

Boron Trioxide (B₂O₃) was adsorbed on coke through boric acid (H₃BO₃) solution, of which the concentration was 0.1%, 0.5%, 1.0%, 2.0% respectively. The existence form and distribution of boron (B) adsorbed on coke were characterized by X-Ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and Inductive coupled plasma (ICP), effect of B₂O₃ adsorbed on coke was investigated by carbon solution loss reaction (CSLR) under the condition of the same weight loss. Results show that: H₃BO₃ changes into B₂O₃ after adsorption treatment, and is adsorbed on coke success-fully; B₂O₃ exhibits negative effect on coke CSLR; with the solution concentration increases, the negative effect is strengthened, and coke’s inner reactivity becomes severer, which is not beneficial for coke strength.     

A semi-industrial scale study of petroleum coke as an additive in cokemaking

The addition of petroleum coke to a typical industrial coal blend used in the production of metallurgical coke was studied. Cokes were produced at semi-industrial scale at the INCAR coking plant, using petroleum coke of different particle size distribution as an additive. Special attention was paid to changes caused in the textural properties (porosity, pore size distribution, fissures at the interface between metallurgical coke and petroleum coke) which have been found to be responsible for variations in the metallurgical coke quality parameters (e.g., mechanical strength and reactivity towards CO₂). Variation in porosity was found to depend on particle size and the proportion of the additive. The decrease in the microporosity (i.e., pore radius<3.7 nm) of the metallurgical cokes observed when petroleum coke is added to the coal blend, is postulated to be one of the main factors responsible for the decrease in the reactivity of these cokes. The variation of the mechanical strength indices can be explained by the changes in porosity and the quality of the interfaces between petroleum coke and metallurgical coke.     

Coke reactivity: Effect of Fe2O3 and K2CO3 addition to the coal charge before carbonization

Six individual coals and one blended metallurgical coal were used in this investigation, and two additives, Fe₂O₃ (up to 1%) and K₂CO₃ (0.5%), were added to each coal before carbonization. Results showed that the additives strongly increase CRI (coke reactivity index) and decrease CSR (coke strength after reaction) of each coke, but there are no significant changes in coke microstructure.     

Effect of pore diffusion on reactivity of lump coke

The gasification of fine-grained and lump coke in CO₂ atmosphere was measured in a laboratory reactor. Owing to the effect of pore diffusion, the reactivity of lump coke at 1050 °C was found to be considerably lower than that of fine-grained coke at otherwise the same conditions. The diffusion effect is more significant for cokes produced by a stamping method than for cokes from top charges. To express the gasification of lump coke, a simplified mathematical model considering the effect of pore diffusion on gasification rate was adopted. Kinetic parameters were determined from experiments with fine-grained coke, while effective diffusivity was evaluated from experiments with a single coke particle. The model fits experimental data of lump coke well. The relation between reactivity and textural characteristics was also examined: the correlation between effective diffusivity and the fraction of largest pore volume was found.     

炼焦煤质量与焦炉加热制度对焦炭热性质的影响

随着高炉冶炼强度及喷煤比的不断提高,炼铁生产对焦炭质量提出了更高的要求。焦炭的反应性和反应后强度是考核焦炭质量的重要指标,影响焦炭反应性和反应后强度的因素很多,本文根据梅山的生产数据,从炼焦煤的质量和焦炉加热制度2个方面对焦炭反应性及反应后强度的影响进行了分析。     

Influence of coal forced oxidation on technological properties of cokes produced at laboratory scale

The effect of coal oxidation in air at 140 °C on the technological properties of cokes obtained at laboratory scale from two medium volatile bituminous coals has been studied. The proximate and ultimate analyses do not show important changes with coal oxidation time. However oxidation clearly has a strong effect on the plastic properties of the coals in view of the fact that the Gieseler fluidity eventually disappears. From this point variations in plastic properties can still be detected by FSI. Other changes, such as a shortening of the length of the saturated fragments of the aliphatic chains, a decrease in the aliphatic hydrogen content and an increase in the oxygen-containing groups are detected by PA-FTIR. It was also found that the main coke quality indices (mechanical strength and reactivity to CO₂) of both coke series are impaired with coal oxidation. A close relationship between reactivity to CO₂ and the micropore specific surface area of the cokes has been corroborated.     

Influence of coal forced oxidation on technological properties of cokes produced at laboratory scale

The effect of coal oxidation in air at 140 °C on the technological properties of cokes obtained at laboratory scale from two medium volatile bituminous coals has been studied. The proximate and ultimate analyses do not show important changes with coal oxidation time. However oxidation clearly has a strong effect on the plastic properties of the coals in view of the fact that the Gieseler fluidity eventually disappears. From this point variations in plastic properties can still be detected by FSI. Other changes, such as a shortening of the length of the saturated fragments of the aliphatic chains, a decrease in the aliphatic hydrogen content and an increase in the oxygen-containing groups are detected by PA-FTIR. It was also found that the main coke quality indices (mechanical strength and reactivity to CO₂) of both coke series are impaired with coal oxidation. A close relationship between reactivity to CO₂ and the micropore specific surface area of the cokes has been corroborated.     

焦炭反应性与反应后强度的关系及其影响因素探讨

为了很好地预测焦炭在高炉中的反应行为,对大量的焦炭进行了检测及数据的分析,说明焦炭反应性与反应后强度之间有良好的负相关性;对焦炭冷态强度与热态性能之间进行了对比,建议焦化企业在保证焦炭的冷态强度合格的同时,更要关注焦炭的热态性能指标;对影响焦炭反应性与反应后强度的反应温度、碱金属、钝化剂等因素进行了试验,指出在生产中应严格控制高炉操作温度,并在按国标方法测定时,加入一定浓度的碱类,以模拟高炉生产的实际过程。提出熄焦时采用一定浓度的硼砂溶液喷洒焦炭,可改善焦炭的热性能。     

Gasification of oil sand coke: Review

The production of synthetic crude from the tar sands in Western Canada has been steadily increasing. Most of the delayed coke produced by Suncor is combusted on site, whereas all fluid coke produced by Syncrude is stockpiled. The database on the chemical and physical properties of the oil sand coke, including the composition and fusion properties of the mineral matter, has been established. The reactivity of the coke was determined by oxygen chemisorption, fixed bed and fluid bed bench scale gasification and pilot plant gasification. The reactivity of the oil sand coke for gasification is rather low and comparable to high rank coals, such as anthracite. Slurrability tests revealed that a solid concentration in water, approaching 70 wt.%, can be achieved. Gasification is the front runner among clean technologies for the conversion of carbonaceous solids to useful products. Several commercial gasifiers are available to cover the wide range of severity. Because of the low reactivity of oil sands coke, high severity conditions are required to achieve high gasification conversion. Such conditions can be attained in entrained bed gasifiers. Gasifiers employing both dry and slurry feeding systems are suitable. A high efficiency, low SO_x and NO_x emissions, as well as a low solid waste production are among the key advantages of the gasification technology compared with the competing technologies. Commercial gasification of oil sands coke is delayed because of the availability of natural gas on the site of the upgrading plants. Potential for the transportation of the oil sand coke to USA for electricity generation using the integrated gasification combined-cycle (IGCC) technology was evaluated.     

Comparative study of reactivity to CO2 of cokes used in stone wool production

The reactivity towards CO₂ of seven types of commercial coke used in stone wool production has been measured in a thermo gravimetric analyser (TGA). The cokes originated from Western and Eastern Europe and from China. For three of the cokes, the porosity, density and surface area were determined. The directly measured porosities of the cokes was slightly low, indicating that there are pores that are not connected with the outer surface. This is supported by the measured densities and microphotos.The measurements showed that the Chinese cokes were the least reactive while the European cokes made on American coal were the most reactive. The reactivity of the one Eastern European coke in the measurements had an intermediate reactivity.Simulations with a cupola model show that 25% more coke is needed for stone wool production if the coke is changed to a type with half the reactivity towards O₂ and CO₂.The TGA method proved to be a good method for ranking the coke with respect to reactivity with CO₂.     

新疆煤相变机理的研究

利用煤岩学对新疆不同变质程度煤进行了相变机理的研究,探讨了焦炭显微结构对焦炭热性能的影响。当焦炭粗粒、片状组分增加,同性组分减少时,焦炭的应性低,反应后强度提高;当焦炭纤维结构增加,粗粒、片状组分减少时,焦炭的反应性增加,反应后强度下降。     

改性花生壳基型焦性状研究

采用六组不同粒级的神木粉煤为原料,质量分数1. 5%和2. 5%NaOH改性花生壳为粘结剂,通过干法冷压成型制备型煤,而后高温干馏制备改性花生壳基型焦。利用红外光谱仪表征其官能团结构,测定改性花生壳基型焦的抗压强度、跌落强度和机械强度等宏观性质。结果表明,神木煤粒度(3～1. 5) mm,质量分数2. 5%NaOH改性花生壳基型焦的性能强度更优,跌落强度98. 4%,抗压强度5 187. 15 N,抗碎强度与耐磨强度分别为82. 08%和17. 92%。NaOH浓度对型焦的性能强度影响不大。随着粉煤粒度减小,型焦宏观性能强度降低。神木煤粒度0. 425 mm,抗碎强度急剧降低至0,耐磨强度高达100%。改性花生壳基型焦红外谱线相对简单,出峰数目少,不同粒级神木煤型焦的红外谱峰峰型相似,出峰位置一致,但峰强弱略有差异。     

碳溶反应温度对高反应性焦炭热态性能的影响

以钢渣为催化剂添加至焦煤中制备高反应性焦炭,研究碳溶反应温度对焦炭热态性能的影响及焦炭反应后的结构变化。结果表明,添加钢渣后,焦炭的反应性提高;随着碳溶反应温度的升高,焦炭的反应性呈线性增加,而反应后强度先缓慢降低然后迅速劣化;焦炭反应后的比表面积先增大而后减小。