硫酸锰溶液除亚铁的研究

研究了菱锰矿硫酸浸出液现有除亚铁工艺热力学，探讨了影响现有除亚铁工艺氧化剂消耗过多以及除亚铁效率低的根本原因，通过改进氧化除亚铁工艺过程，结果表明：较大地提高了软锰矿的利用效率，使软锰矿的消耗量降低约50％。     

Impurities Removal from Metallurgical-Grade Silicon by Combined Sn-Si and Al-Si Refining Processes

The purification of metallurgical-grade silicon (MG-Si) by combined solvent refining processes has been studied. The final high-purity silicon was recovered through Sn-Si refining and Al-Si refining processes in sequence after acid leaching, and the removal mechanism of impurities was explored. Inductively coupled plasma (ICP) chemical analysis revealed the concentrations of main impurities including B and P, and typical metallic impurities except for solvents Sn and Al were reduced to below 1 ppmw. The final removal efficiencies of B and P were 97.7 pct and 99.8 pct, respectively, and those of most metallic impurities were above 99.9 pct. SEM analysis showed that P-containing phases (Al-Ca-Mg-Si-P and Al-Si-P) formed on the surface of refined Si after Sn-Si refining and Al-Si refining, which was confirmed to be the main approach for P removal. It was also found that the formation of binary silicide such as Fe₃Si₇ and Mn₁₁Si₁₉ or multicomponent phases such as Ca-Mg-Si phase occurred during the solvent refining process, and they segregated on the grain boundaries in Si or attached to the surface of Si, which led to high removal efficiency of metallic impurities by the solvent refining process.     

Nitrogen Removal Using Combined Ultracompact Biofilm Reactor-Packed Bed System

A predenitrification system consisting of an ultracompact biofilm reactor (UCBR) and a packed bed column was used for removing nitrogen from synthetically simulated wastewater. The UCBR column was maintained under aerobic conditions to favor nitrification process, while the packed bed column was operated under an anoxic environment for denitrification process. A peristaltic pump was used to recycle fluid between the anoxic-packed bed and aerobic-UCBR columns to facilitate nitrogen removal. Five recycle ratios (R) were investigated, namely, 3, 4, 5, 6, and 10. The highest average total nitrogen (TN) removal rate was achieved at R = 4. The NH4+–N, TN, and chemical oxygen demand (COD) removal rates at this R were 0.56±0.05?kg NH4+–N/m3/day, 0.39±0.09?kg TN/m3/day, and 1.83±0.18?kg COD/m3/day, respectively. It was noted that poor nitrification in the UCBR was accompanied by a corresponding reduction in overall TN removal efficiency. This observation suggested that nitrification process was the limiting step for TN removal in this setup. Thus, the performance of this predenitrification system could be enhanced by optimizing the performance of the nitrification process.     

Kinetics and thermodynamics modeling of Nd(III) removal from aqueous solution using modified Amberlite XAD7

New adsorbent material was obtained by modification of commercial Amberlite XAD7 with thiourea that represents a non-toxic, cheap and environmentally friendly extractant. Prepared adsorbent was used for removal of neodymium ions from aqueous solutions. Thiourea modified Amberlite involved in this study shows good adsorption capacities (74.3 mg/g) and excellent efficiency during Nd removal process. In order to elucidate the mechanism of the Nd adsorption process kinetic, thermodynamic and equilibrium studies were performed, establishing this way which kinetic model better describes the Nd adsorption process. Moreover the thermodynamic studies prove that the Nd adsorption on thiourea modified Amberlite XAD7 is an endothermic and spontaneous process.     

Removal Mechanism of Zn,Pb and Alkalis from Metallurgical Dusts in Direct Reduction Process

The high-temperature tube furnace was applied to simulate the rotary hearth furnace （RHF） for the direct reduction of zinc-bearing dusts from steel plants. The removal mechanism of Zn, Pb and alkalis from cold bonded briquettes made by mixing metallurgical wastes, such as dust from bag house filter, OG sludge, fine converter ash and dust from the third electric field precipitator of the sinter strand, in various proportions was investigated. More than 70% of metallization rate, more than 95% of zinc removal rate, 80% of lead removal, as well as more than 80M of K and Na removal rates were achieved for the briquettes kept at 1473-1603 K for 15 min during the direct reduction process respectively. The soot generated in the direct reduction process was studied by chromatography, X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The results suggested that the main phases of the soot were ZnO, KC1, NaC1 and 4ZnO · ZnC12 · 5H20. Furthermore, the content of Zn reached 64.2 %, which could be used as secondary resources for zinc making. It was concluded that KC1 and NaC1 in secondary dust resulted from the volatilization from the briquettes, whilst ZnO and PbO were produced by the oxidation of Zn or lead vapour from briquettes by direct reduction.     

In Situ Microscale Analyses of Activated Sludge Flocs in the Enhanced Biological Phosphate Removal Process by the Use of Microelectrodes and Fluorescent In Situ Hybridization

Phosphate concentration microprofiles were measured within activated sludge flocs in the enhanced biological phosphate removal (EBPR) process, and a fluorescent in situ hybridization and clone library analysis were conducted to indentify polyphosphate accumulating organisms (PAOs). The center of the flocs had the highest phosphate concentrations, and the stratification of the flocs found by microprofiling indicated that the PAOs were probably distributed evenly throughout the flocs. Under the assumption that the phosphate, which was generated because of phosphate release by microbial activity, was not consumed by microbes and was only transferred from the flocs to the bulk by diffusion during anaerobic conditions, the effective diffusion coefficient (Df) for phosphate release within the flocs was calculated to be 3.33×10?7?cm2/s at the end of the anaerobic phase of the EBPR process. These results provide a better understanding of the phosphate removal mechanism, and this understanding of the internal function of flocs can lead to improvement in the modeling, design, and operation of the biological phosphorus removal process.     

Short-Term Effects of Wastewater Biodegradability on Biological Phosphorus Removal

A steady-state laboratory-scale sequencing batch reactor process for biological phosphorus removal (BPR) was developed, and the influence of wastewater biodegradability on BPR was studied in batch tests. Biodegradability was expressed in this work as the readily biodegradable fraction of wastewater COD (rbCOD) present in the mixed liquor after the anaerobic stage of the anaerobic/oxic cycle of the BPR process. The rbCOD fraction was changed by varying the organic composition of synthetic wastewater (different carbohydrates were used: saccharose, cellobiose, starch, and cellulose) or varying the anaerobic retention time (1.25, 4, 9, and 24 h) when only one kind of low biodegradable synthetic wastewater (starch composed) was used. A clear positive trend was observed between rbCOD and anaerobic P release, but such a clear relationship was not observed with BOD5 measurements. Soluble carbohydrates allowed a BPR mechanism, but particulate carbohydrates seemed to cause nonbiological P removal. An increase in anaerobic retention time improved rbCOD concentrations up to 50%, approximately, and P removal, but excessive retention times, >9 h, should be used to reach good BPR results.     

可溶阳极电解生产1~#电钴的工艺研究

介绍采用Ｐ２０４ 萃取除Ｆｅ、Ｚｎ 和Ｍｎ,ＨＡ－ＰＥ２０６协萃体系除Ｃｕ,ＨＡ－ＰＥ２０６协萃体系除Ｎｉ、Ｃｕ,并用净化后液进行可溶阳极电解得到１＃ 电解钴的工艺研究过程。     

Investigation on the removal efficiency of inclusions in Al-killed liquid steel in different refining processes

Industry trials were carried out to study the removal efficiency of inclusions in Al-killed liquid steel in the processes of BOF–LF–RH–CC and BOF–RH–CC. It was found that the removal efficiency of inclusions has a high dependence on inclusion types. Solid inclusions are more easily to be removed than liquid inclusions. The removal efficiency of solid Al₂O₃ inclusions is higher than that of solid CaO–Al₂O₃–MgO inclusions. As liquid CaO–Al₂O₃–MgO inclusions coexisted with solid CaO–Al₂O₃–MgO inclusions in the liquid steel, the low removal efficiency of inclusions in RH degassing process was found in BOF–LF–RH–CC process. However, high removal efficiency and ultra-low total oxygen (T.O) content were obtained in BOF–RH–CC process because the inclusions were mainly composed of solid Al₂O₃ although initial T.O content before RH degassing was relatively high. This is due to the fact that solid Al₂O₃ tends to form cluster-shaped inclusions which have both a higher contact angle and a lower work of adhesion with steel than calcium aluminate, resulting in easier removal by RH degassing. Therefore, it is proposed to weaken steel–slag reaction and calcium treatment before RH degassing to retain solid Al₂O₃ inclusions in the steel.     

锌冶炼渣浸出液除铁研究

锌湿法冶炼渣酸性浸出液中铁含量通常较高,分别以空气、双氧水和二氧化锰为氧化剂,对氧化中和除铁的效果进行比较,并研究了双氧水氧化中和除铁法中pH和反应温度对除铁效果的影响。结果表明,双氧水氧化中和除铁法是最佳的除铁方法,常温下pH 5以上除铁效果较好,除铁效果随温度升高而增强,且过滤性能较好。     

Nitrification∕Denitrification in Intermittent Aeration Process for Swine Wastewater Treatment

A continuous-flow intermittent aeration (IA) process has been studied for nitrogen removal from anaerobically digested swine wastewater with high ammonium content. High nitrogen removal efficiency of average 91% total Kjeldahl nitrogen and 92% NH4-N was achieved in an IA system with an alteration of 1-h aeration and 1-h nonaeration. Nitrification and denitrification were found to be responsible for the nitrogen removal in the system. Nitrite and nitrate in the effluent were less than 1.0 mg∕L and 8.0 mg∕L, respectively. The specific nitrification and denitrification rates of the single-sludge IA culture were determined through batch experiments as 2.79–3.70 mgNO3-N∕g volatile suspended solids-h and 0.59–1.03 mgNO3-N∕g volatile suspended solids-h, respectively. In the IA process, the aeration period created favorable conditions for nitrifying bacteria (dissolved oxygen = 4–6 mg∕L and oxidation-reduction potential = 80–100 mV), while the nonaeration period provided good environment for denitrifying bacteria (dissolved oxygen < 1 mg∕L and oxidation-reduction potential as low as 0 mV). Ammonia volatilization in the IA process was negligible (<0.008%). Denitrification activity in the IA process prevented nitrate from accumulation and significant pH change in the system, which is critical for nitrogen removal from swine wastewater with high ammonium content.     

某高碱贫铀矿石的微生物酸法池浸探索

先采用盐酸去除某高碱性铀矿石中的大部分碱性物质,然后采用微生物酸法池浸技术对铀进行浸出。结果表明,大粒径(5mm)矿石中的铀很难被提取,去除部分大粒径矿石后,当碱性物质去除率达65%时,铀的浸出率可以达到91.2%。     

Experimental Investigation and Optimization of Machining Process Parameters in AISI D2 Steel Under Conventional EDM and Cryogenically Cooled EDM Process

Electrical discharge machining (EDM) is a well-established machining option for manufacturing geometrically complex or hard material parts that are extremely difficult-to-machine by conventional machining processes. In this research work, investigations were carried out on the machining of AISI D2 tool steel under conventional EDM and cryogenically cooled EDM process (CCEDM). The input process parameter such as current (I_p), pulse on time (T_on) and gap voltage (V) were investigated and the output responses like electrode wear ratio, metal removal rate and surface roughness were explored. Experiments were conducted using L₁₈ orthogonal array in EDM machine. Experimental results showed reductions in the electrode wear of 16% over CCEDM process. A grey relational analysis was used to solve the EDM process with multi performance characteristics to optimize EDM parameters.     

Biological Removal of Gaseous VOCs from Automotive Painting Operations

Among the pollutants that automotive plants produce, volatile organic compound (VOC) emissions due to paint solvents from painting operations are the largest in quantity. The current control process, based on vapor-phase adsorption followed by thermal oxidation, is costly to install and operate. At Ford, a cost-effective method of removing VOCs has been investigated that involves converting an existing spraybooth scrubber system to a biological reactor. This paper reports the results of a pilot-scale investigation in which two activated-sludge bioreactors, one with and the other without powdered activated carbon (PAC), were operated in parallel for 16 months. The primary findings include (1) The biological VOC removal process was technically feasible, and a scrubber system at a typical assembly plant is sufficiently large to handle the solvent loading used under normal vehicle-production conditions; (2) as compared to the adsorption∕thermal oxidation process, the biological process was found to be comparable in VOC removal efficiency, an order of magnitude more cost-effective in capital cost, and a factor of two more cost-effective in operating and maintenance cost; and (3) the bioreactors effectively captured and degraded hydrophilic paint solvents (methyl ethyl ketone, n-butanol, and butyl cellosolve) that were fed via the vapor phase. Toluene, a hydrophobic solvent, was also well-captured and degraded (74 to 91% without PAC and 86 to 93% with PAC).     

Kinetics and thermodynamics modeling of Nd(Ⅲ) removal from aqueous solution using modified Amberlite XAD7

New adso rbent material was obtained by modification of commercial Amberlite XAD7 with thiourea that represents a non-toxic,cheap and environmentally friendly extractant.Prepared adsorbent was used for removal of neodymium ions from aqueous solutions.Thiourea modified Amberlite involved in this study shows good adsorption capacities(74.3 mg/g) and excellent efficiency during Nd removal process.In order to elucidate the mechanism of the Nd adsorption process kinetic,thermodynamic and equilibrium studies were performed,establishing this way which kinetic model better describes the Nd adsorption process.Moreover the thermodynamic studies prove that the Nd adsorption on thiourea modified Amberlite XAD7 is an endothermic and spontaneous process.     

真空感应熔炼中夹杂物运动行为数值模拟

为了促进真空感应熔炼GH4169合金过程中夹杂物的去除,建立了电磁-流动-粒子跟踪耦合数学模型,研究了真空感应熔炼过程中熔液流动与夹杂物运动的规律,对比了不同冶炼工艺参数下熔池中流场和夹杂物运动特点,提出了一种促进真空感应熔炼过程中夹杂物去除的工艺优化方法。结果表明,真空感应熔炼过程中,熔池流场中存在2个漩涡,加快漩涡的运动速度可以促进熔池内夹杂物的去除,熔液流动速度随着熔炼的进行先升高后下降,最终趋于稳定。随着电压增加,熔液平均流动速度增加,熔池内夹杂物总去除率升高。随着电流频率升高,熔液平均流动速度降低,熔池内夹杂物总去除率降低。因此可通过增大电压、减小电流频率的方法,增大熔液流动速度,促进真空感应熔炼GH4169合金过程中夹杂物的去除,工艺参数由400 V、3 400 Hz优化为420 V、3 200 Hz后,夹杂物总去除率由91.98%增大到94.87%,提高了2.89%。     

Practical Modeling of SVE Performance at a Jet-Fuel Spill Site

A coupled flow and transport model (VENT3D) was used to simulate the performance of soil vapor extraction at a jet-fuel (JP-4) contaminated site. The contaminant mixture was approximated with 10 surrogate components categorized by carbon number class. The contaminant was distributed heterogeneously throughout the soil. The initial total contaminant mass was the only parameter that was adjusted, and it was fit to the observed removal during the pilot tests. The predicted total mass removal using the most general approach matched the observed hydrocarbon mass removal within ±4%. The effects of the following selected simplifying assumptions were examined with the model: (1) uniform contaminant distribution; (2) 2D horizontal flow; and (3) single equivalent contaminant. The uniform soil contamination distribution and the horizontal flow assumptions yielded similar results—both estimated removal rates that were initially higher by 30% and eventually overpredicted the total removal by 10%. The equivalent single-component approximation underpredicted the removal by as much as 50% during the first half of the operation and then overpredicted the removal, ultimately overpredicting the total removal by <10%.     

Evaporation Removal of Boron from Metallurgical-Grade Silicon Using CaO-CaCl2-SiO2 Slag

In order to optimize the B removal during slag-refining process for solar-grade silicon production, a new process for the removal of B in molten Si was proposed based on the principle of oxidized chlorination and evaporation. B can be generated and evaporated in the form of B-containing gas on the basis of calculated vapor pressures of forming species in the BO_1.5-CaCl₂ slag at 1723 K (1450 °C). CaO-SiO₂-CaCl₂ slag was selected to remove B in molten Si. In the slag-refining experiments, compared with the binary systems of CaO-CaCl₂ and SiO₂-CaCl₂ slag, the ternary slag system CaO-SiO₂-CaCl₂ showed a better potential (86 pct) for B removal. Furthermore, the relationships among the removal efficiency, the estimated evaporative efficiency, and the partition ratio were all discussed.     

铜火法冶炼过程中新型脱杂剂的应用实践

通过对铜火法吹炼、精炼过程中铅、砷、锑、铋等主要杂质的分布状态、脱除机理和物相进行分析研究,开发出一种新型脱杂剂(主要成分为含钠钙的高活性碳酸盐),通过新型脱杂剂在铜火法吹炼、精炼段的生产应用,形成了铜火法吹炼、精炼联合除杂工艺,砷、锑、铋脱除率分别由42.19%、22.98%、74.02%提高至54.18%、36.35%、80.41%,确保了高杂原料条件下的阳极铜质量稳定,拓宽了公司原料适应范围。      

Combined System for Biological Removal of Nitrogen and Carbon from a Fish Cannery Wastewater

A combined system composed of three sequentially arranged reactors, anaerobic-anoxic-aerobic reactors, was used to treat the wastewater generated in the tuna cookers of a fish canning factory. These wastewaters are characterized by high chemical oxygen demand (COD) and nitrogen concentrations. The anaerobic process was performed in an upflow anaerobic sludge blanket reactor operated in two steps. During Step I different influent COD concentrations were applied and organic loading rates (OLRs) up to 4 g COD/(L?d) were achieved. During Step II hydraulic retention time (HRT) was varied from 0.5 to 0.8 days while COD concentration in the influent was constant at 6 g COD/L. The OLRs treated were up to 15 g COD/(L?d). When HRTs longer than 0.8 days were used, COD removal percentages of 60% were obtained and these values decreased to 40% for a HRT of 0.5 days. The denitrification process carried out in an upflow anoxic filter was clearly influenced by the amount of carbon source supplied. When available carbon was present, the necessary COD/N ratio for complete denitrification was around 4 and denitrification percentages of 80% were obtained. The nitrification process was successful and was almost unaffected by the presence of organic carbon (0.2–0.8 g TOC/L), with ammonia removal percentages of 100%. Three recycling ratios (R/F) between the denitrification and nitrification reactors were applied at 1, 2, and 2.5. The overall balance of the combined system indicated that COD and N removal percentages of 90% and up to 60%, respectively, were achieved when the R/F ratio was between 2 and 2.5.