Optimization of experimental conditions for recovery of coking coal fines by oil agglomeration technique

The significance of coking coal in the metallurgical sector as well as the meager coking coal reserves across the globe increase the necessity to recover coking coal fines from the fine coking coal slurries generated from coal preparation and utilization activities. Oil agglomeration studies were carried out by varying the experimental conditions for maximum recovery of coking coal fines i.e., yield of the agglomerates. The various operational parameters studied were oil dosage, agitation speed, agglomeration time and pulp density. By using Taguchi experimental design, oil dosage (20%), agitation speed (1100 rpm), agglomeration time (3 min) and pulp density (4.5%) were identified as the optimized conditions. A confirmation experiment has also been carried out at the optimized conditions. The percentage contribution of each parameter on agglomerate yield was analyzed by adopting analysis of variance (ANOVA) statistical method as well as multiple linear regression analysis. The order of influence of the parameters on the agglomerate yield is of the following order: pulp density > oil dosage > agitation speed > agglomeration time. A mathematical model was developed to fit the set of experimental conditions with the yield obtained at each test run and also at the optimized conditions. The experimentally obtained yield was compared with the predicted yield of the model and the results indicate a maximum error of 5% between the two. A maximum yield of 90.42% predicted at the optimized conditions appeared to be in close agreement with the experimental yield thus indicating the accuracy of the model in predicting the results.     

Optimization of some parameters on agglomeration performance of Zonguldak bituminous coal by oil agglomeration

In this study, the optimization of some parameters on agglomeration performance of Zonguldak bituminous coal by oil agglomeration was discussed. A three-level Box-Behnken design combining with a response surface methodology (RSM) and quadratic programming (QP) were employed for modeling and optimization some operations parameters on oil agglomeration performance. The relationship between the responses, i.e., grade and recovery, and four process parameters, i.e., amount of oil, agitation time, agitation rate and solid content were presented as empirical model equations for both grade and recovery on oil agglomeration. The model equations were then optimized individually using the quadratic programming method to maximize both for grade and recovery within the experimental range studied. The optimum conditions were found to be 14.61% for amount of oil, 8.94 min for agitation time, 1554 rpm for agitation rate and 5% for solid content to achieve the maximum grade. The maximum model prediction of 0.650 grade at these optimum conditions is higher than any value obtained in the initial tests conducted. Similarly, the conditions for maximum recovery were found to be 20.60% for amount of oil, 5 min for agitation time, 1800 rpm for agitation rate and 19.48% for solid content with a prediction of 96.90% recovery, which is also higher than any other recovery obtained in the initial tests conducted.     

Iterative model-based experimental design for spherical agglomeration processes

Spherical agglomeration (SA) is a process intensification strategy, which can reduce the number of unit operations in pharmaceutical manufacturing. SA merges drug substance crystallization with drug product wet granulation, reducing capital, and operating costs. However, SA is a highly nonlinear process, thus for its efficient operation model-based design and control strategies are beneficial. These require the development of a high-fidelity process model with appropriately estimated parameters. There are two major problems associated with the development of a high-fidelity process models—(i) selection of the appropriate model corresponding to the underlying process mechanisms, and (ii) accurate estimation of the parameters. This work focuses on the identification of the best fitting model that correlates with experimental observations using cross-validation experiments. Further, an iterative model-based experimental design strategy is developed, which uses D-optimal experimental design criterion to minimize the number of experiments necessary to obtain accurate parameter estimates.     

Investigation of kinetics of agglomerate growth in oil agglomeration process

In this study, the kinetics of agglomerate growth in a batch oil agglomeration process has been studied using bituminous coal. The effect of operating variables such as kerosene concentration, pulp density and speed of agitation on the agglomeration process was investigated. It has been found that the second-order kinetic equation describes the growth of agglomerates adequately. The growth of the agglomerates in the oil agglomeration process shows a self-preserving growth. Using this, a characteristic curve has been developed. For the prediction of the size distribution of the agglomerates, the d₅₀ values of the agglomerates must be known. Therefore, a model has been developed by using the kinetic equation for estimation of d₅₀ values of agglomerates for this coal. It was shown that the size distribution of the agglomerates for any levels of the process variables studied can be predicted using the equation of characteristic curve and d₅₀ values. Knowledge obtained from this study will be helpful for technological advancement of this kind of study.     

Investigation of the effect of agglomeration time, pH and various salts on the cleaning of Zonguldak bituminous coal by oil agglomeration

In this study, the effects of bridging liquid concentration, agglomeration time, pH and various salts on the combustible recovery and ash contents of the agglomerated products have been investigated. Kerosene was used as bridging liquid. The optimum values of kerosene concentration, pH and agglomeration time have been determined as 20 wt%, 7.5 and 15 min, respectively. Metallic salts, such as FeSO₄, NaCl, FeCl₃, Al₂(SO₄)₃ were used in the experiments in which the effects of salts were investigated. While the combustible recovery slightly increased depending on the increase in the concentration of NaCl, very small decreases have been recorded in the recoveries depending on the increase in the concentration of the FeCl₃. A considerable reduction occurs in the agglomeration recovery with the increasing concentration of FeSO₄, while the combustible recovery slightly decreases at low concentration of Al₂(SO₄)₃.     

The investigation of coal-pyrite/lignite concentration and their separation in the artificial mixture by oil agglomeration

In this study, the concentration of coal-pyrite and lignite taken from Yozgat-Ayridam (Turkey) Coal Management was investigated by oil agglomeration.In the previous studies, the agglomeration of coal-pyrite was investigated using different bridging liquids (fuel oil, diesel oil and kerosene) and the combination of reagent (KEX, Acorga M5397)+kerosene. When using only bridging liquids, the agglomeration recovery of pyrite was very low. To increase the hydrophobicity of pyrite, KEX was used. However, the pyrite was not agglomerated with an acceptable recovery. But when using Acorga M5397, which is a chelating reagent, the agglomeration recovery of pyrite was increased. The pyrite was agglomerated with a recovery of 76.70 wt% by single-stage agglomeration.In the optimum conditions which were determined for coal-pyrite, the agglomeration recovery of lignite was investigated. It was found that the lignite could not be agglomerated with an acceptable recovery.To investigate the separation of coal-pyrite and lignite, the artificial mixture of coal-pyrite and lignite was prepared with the weight ratio of 1/4 of coal-pyrite and lignite. It was found that the pyrite could be agglomerated at a recovery of 96.54% with three-stage agglomeration process. The lignite concentrate was produced with a recovery of 73.96 wt% and the pyrite content of 0.86 wt%.These findings showed that the coal-pyrite and lignite could be separated by oil agglomeration using appropriate reagent and bridging liquid.     

Modified oil agglomeration process for coal beneficiation. iv. pilot-plant demonstration of the simultaneous grinding-agglomeration process

Simultaneous grinding and agglomeration (SGA) in the novel Szego Mill allows significant simplifications and energy savings. The excess grinding energy is used for mixing and agglomerate formation. Results are reported over a range of operating conditions. The SGA process has been demonstrated in the laboratory and in a 12 tonnes/day pilot plant with satisfactory results. The economics of coal beneficiation for slurry fuel preparation is considered.     

Application of Box–Wilson experimental design method for the photodegradation of textile dyestuff with UV/H2O2 process

Photodegradation of textile dyestuffs Chrysophenine Yellow (DY12), Congo Red (DR28) and Remazol Black B (RB5) by the UV/H₂O₂ process was investigated in a laboratory scale photoreactor equipped with a 16-W low-pressure mercury vapour lamp. The Box–Wilson experimental design was employed to evaluate the effects of major process variables, dyestuff and hydrogen peroxide concentrations and irradiation time on decolorization efficiency. Response function coefficients were determined by regression analysis of experimental data and predictions were found to be in good agreement with the experimental results. For 100 mg l⁻¹ DY12, RB5 and DR28 for instance, the optimum hydrogen peroxide concentration and irradiation time were found to be 45 mM for 58 min, 45 mM for 58 min and 60 mM for 120 min with 100, 100 and 85.7% efficiencies, respectively. Further increases in oxidant concentration led to slight decreases in decolorization efficiencies according to the response function, most probably due to the scavenging effect of excess hydrogen peroxide on hydroxyl radicals. And this was confirmed by the repeated experiments performed at the points of concern. Increasing the dyestuff concentration also decreased the decolorization efficiency even at higher concentrations of oxidant and longer irradiation times. The photodegradation of dyestuffs were found to follow a first-order reaction law.     

分散剂在尾煤选择性聚团脱灰中的应用

利用选择性聚团法对平顶山尾煤进行脱灰分选 ,加入分散剂后 ,在一定程度上可降低超细精煤的灰分。选择六偏磷酸钠、硅酸钠、腐植酸钠、木素磺酸钙、碳酸钠、糊精 6种分散剂进行了应用实验 ;并通过测量矿浆的ZETA电位分析了这些分散剂的作用机理。     

正交设计法研究乙酸仲丁酯的合成

以NaHSO4·H2O为催化剂,冰乙酸、仲丁醇为原料合成乙酸仲丁酯。利用正交设计法确定了反应的优化条件:催化剂加入量为0.8 g,反应时间为60 min,带水剂加入量为15 mL,醇酸摩尔比为2.5∶1,酯化率可达85%左右。     

Simultaneous particulate design of primary and agglomerated crystals of steroid by spherical agglomeration in liquid for dry powder inhalation

Spherical agglomerates of steroid KSR-592, consisting of fine primary drug crystals suitable for dry powder inhalation (DPI), were prepared by the spherical agglomeration method in liquid with a bridging liquid. It was found that the particle size of primary crystals increased until the dispersing medium was saturated with the bridging liquid, whereas the spherical agglomeration of primary crystals was continued even after the saturation of medium with the bridging liquid. The growth rates of primary crystals and agglomerates increased with an increase in the temperature and/or a reduction in the agitation speed of the system. The agglomerates were easily disintegrated into the primary crystals depositing ideally on carrier lactose particles for DPI by mixing. The in vitro efficiency of the mixed system of lactose and disintegrated primary crystals of drug was 2 to 3 times higher than that of crystals prepared conventionally. Furthermore, the soft agglomerates disintegrated easily into respirable particles in air stream when emitted from the inhalation device were prepared by reducing the agitation speed after the dispersing medium was saturated with the bridging liquid.     

Modified oil agglomeration process for coal beneficiation. I. Mineral matter liberation by fine grinding with the szego mill

The spherical oil agglomeration technique developed at the National Research Council of Canada (NRC) is an excellent method for cleaning and recovering very small coal particles. The finely ground coal, dispersed in water, is contacted with oil by intensive mixing. The hydrophobic coal particles collect onto the oil droplets to form the agglomerates which are then separated from the aqueous phase by screening. A Szego Mill was used to wet grind Minto (New Brunswick) coal which was then subjected to laboratory agglomeration by the NRC procedure. A comparison with coal ground in a ball mill indicated superior ash rejection. The improved performance is attributed to better mineral liberation which is enhanced by the more flaky particles produced in the Szego Mill.     

An advanced ash fusion study on the melting behaviour of coal,oil shale and blends under gasification conditions using picture analysis andgraphing method

This study investigates the potential of solid fuel blending as an effective approach to manipulate ash melting behaviour to alleviate ash-related problems during gasification, thus improving design, operabil-ity and safety. The ash fusion characteristics of Qinghai bituminous coal together with Fushun, Xinghua and Laoheishan oil shales (and their respective blends) were quantified using a novel picture analysis and graphing method, which incorporates conventional ash fusion study, dilatometry and sintering strength test, in a CO/CO2 atmosphere. This image-based characterisation method was used to monitor and quan-tify the complete melting behaviour of ash samples from room temperature to 1520 ℃. The impacts of blending on compositional changes during heating were determined experimentally via X-ray diffraction and validated computationally using FactSage. Results showed that the melting point of Qinghai coal ash to be the lowest at 1116 ℃, but would increase up to 1208 ℃, 1161 ℃ and 1160 ℃ with the addition of 30％–50％ of Laoheishan, Fushun, and Xinghua oil shales, respectively. The formation of high-melting anorthite and mullite structures inhibits the formation of low-melting hercynite. However, the sintering point of Qinghai coal ash was seen to decrease from 1005 ℃ to 855 ℃, 834 ℃, and 819 ℃ in the same blends due to the formation of low-melting aluminosilicate. Results also showed that blending directly influences the sintering strength during the various stages of melting. The key finding from this study is that it is possible to mitigate against the severe ash slagging and fouling issue arising from high calcium and iron coals by co-gasification with a high silica-alumina oil shale. Moreover, blending coals with oil shales can also modify the ash melting behaviour of fuels to create the optimal ash chemistry that meets the design specification of the gasifier, without adversely affecting thermal performance.     

Research on the mechanism of bed agglomeration and superheater fouling in CFB boiler fired pure petroleum coke

Circulating fluidized bed combustion is an effective method for the clean and efficient utilization of high-sulphur petroleum coke. In the actual production and operation process, there are serious problems of bed agglomeration and superheater fouling. The chemical and mineral compositions of the deposition were analyzed by X-ray diffraction (XRD) and X-ray fluorescence spectroscopy (XRF), and the effects of CaO sulphation and V₂O₅ on bed agglomeration and superheater deposits were studied through targeted experiments. The research results show that the sulphation process of CaO is the cause of bed agglomeration, and the superheater fouling is the result of the combined action of K₂SO₄ condensation and CaO sulphation; V₂O₅ in petroleum coke ash catalyzes the oxidation reaction of SO₂ to accelerate the sulphation of CaO, thereby accelerating the development of bed agglomeration and superheater fouling.     

Application of an experimental design method to study the performance of electrochlorination cells

A study of the effects of some parameters on the active chlorine production from aqueous sodium chloride solutions in the hypochlorite electrochemical production cells was undertaken. These varying parameters included the anodic surface area (S_a), the ratio of anodic and cathodic surface areas () the inter-electrode gap, and the type of the cathode used. In addition, a study of the performance of some electrochemical cells that differ in the type of anodes (platinum-coated titanium, ruthenium-coated titanium, and graphite) was made. By means of the experimental design method employing a full factorial of2² the effects ofthe most influencing parameters, the set-up of optimum conditions, and the formation of optimal concentration of active chlorine were assessed. Under the following conditions, a concentration of as high as 65.67 g/L of active chlorine was gained: ruthenium-coated titanium anode (S_a = 24 cm²); titanium cathode, ; inter-electrode gap, 0.5 cm; current density, 35 A/dm² ; temperature, 20°C; concentration of NaCl aqueous solution, 3 M; time, 2 h.     

水煤浆加压气化炉用Cr2O3-Al2O3-ZrO2砖的损毁模式

详细分析了陕西渭河煤化工集团有限责任公司的德士古(Texaco)水煤浆加压气化炉用Cr2O3-Al2O3-ZtO2砖的损毁模式及影响因素,并提出了降低耐火砖损毁的方法.认为块状剥落、烧蚀损伤、冲蚀损伤和机械损坏是造成耐火砖损毁的主要原因;提高耐火砖自身的抗侵蚀能力,改善炉衬砌筑结构和炉内工况气氛,控制适当的炉渣特性,以及采用正确的修理维护方法,是提高德士古水煤浆加压气化炉用Cr2O3-Al2O3-ZrO2砖使用寿命的主要途径.经过几年的反复试验和技术改进,特别是采用中钢集团洛阳耐火材料研究院生产的Cr2O3-Al2O3-ZrO2砖后,渭河煤化工集团有限责任公司的德士古水煤浆加压气化炉用Cr2O3-Al2O3-ZrO2砖的使用寿命已从原设计的8000 h提高到现在的23000 h.     

均匀设计试验方法及其在Ni-P-MoS2化学镀上的应用

均匀设计是基于试验点在整个试验范围内均匀散布的一种试验设计方法。介绍了该法的特点及其软件的基本功能与基本操作过程。从均匀设计试验方案的建立、试验结果的回归分析及优化、镀液最佳配方的试验验证3个方面介绍了均匀设计法在Ni-P-MoS2化学复合镀中的应用，并得到了最佳的Ni-P-MoS2化学复合镀液配方。该法应用于化学镀的工艺试验，简便可行。     

年青褐煤H_2O_2降解生产黄腐酸工艺及产物性质

对云南金所年青褐煤进行H2O2降解制备黄腐酸的试验研究,通过透析将黄腐酸分为相对分子质量不同的7个级分,对其进行元素分析、红外光谱等研究。结果表明:对黄腐酸产率影响最大的因素是煤与氧化剂质量比,其次是氧化降解时间,氧化剂质量分数影响最小。优化工艺:煤与H2O2质量比1∶0.38,氧化降解温度30℃,氧化降解时间180 min,H2O2质量分数为15%,在此条件下黄腐酸产率达19%。理化分析结果表明:降解产物黄腐酸中总酸性基团、羧基质量摩尔浓度显著提高;随着相对分子质量的增加,氧元素和含氧官能团减少。