Pilot study on microbial treatment of high concentration chromium wastewater from cold rolling mills

The microbial treatment of wastewater containing a high concentration of chromium from cold rolling mills was carried out as a pilot study. The pilot-scale equipment, technological process and results are described in this paper. Two kinds of wastewater with a high concentration of chromium were tested ： one from a color coating line ; the other from a silicon steel line. The removal effect of Cr^6＋ , T-Cr and chemical oxygen demand （COD） in wastewater was studied. The results showed that this microbial treatment technology could be used to treat the above two kinds of chromium-containing wastewater. The average concentrations of Cr^6＋ in the color coating line effluent and the silicon steel line effluent were 0.02 mg/L and 0.04 mg/L respectively, and the average concentrations of T-Cr in the effluents were 0.71 mg/L and 0.74 mg/L respectively. Both were lower than the Sewage Discharge Standard （Cr^6＋ 〈 0.5 mg/L,T-Cr 〈 1.5 mg/L）. Furthermore, up to 60% of the COD was removed from chromate wastewater containing a high concentration COD （ 〉 3 g/L）. The removal rate of COD was lower than 25% for chromate wastewater containing a low concentration COD （ 〈 3 g/L）. Adding a flocculating agent was one of the effective ways of improving the COD removal rate from chromium-containing wastewater.

Research on Lubrication Behaviors and Mechanism of Nano-Copper Used in Emulsions for Strip Cold Rolling

In this paper,nano-Cu particles with an average size of smaller than 20 nm were dispersed under ultrasonic agitation in emulsions for cold rolling of steel strips.The tribological properties of the cold rolling emulsion doped with nano-Cu particles were evaluated by using a four-ball machine,and the worn surfaces of the steel balls were checked by an optical microscope.A JC2000C1 wetting angle tester was also applied to study the variation in the emulsion's wetting performance when nano-Cu particles were incorporated.Furthermore,the lubricity of the emulsion doped with nano-Cu for steel strip cold rolling was evaluated on a four-high rolling mill for comparison with the emulsion without using nano-Cu particles.Test results indicated that nano-Cu particles as the additive used in cold rolling emulsion were able to improve the wetting property,friction-reducing,anti-wear,and extreme pressure performance of the base stock significantly.At the same time,nano-Cu particles also showed good lubricity to the cold-rolled steel strips.Namely,the cold-rolled steel strips under the lubrication of the cold rolling emulsion containing nano-Cu particles had considerably decreased the after-rolling thickness and achieved excellent surface quality as well.Finally,the lubrication mechanism of nano-Cu particles in the emulsion for cold rolling of steel strips was discussed.

Two-stage treatment process of pickling wastewater in the cold-rolling production of stainless steel

Based on the characteristics of pickling wastewater in the cold-rolling production of stainless steel, a new processing route, featuring source sludge reduction, wastewater two-stage treatment, heavy metal-contained sludge and calcium salt sludge separating recovery, was proposed. As shown by the research results, after the two-stage process treatment, the effluent water can steadily reach the emission standards, the sludge yield can be decreased by more than 8% ; within the heavy metal-contained sludge, the recovery rates of Fc,Cr and Ni can either reach or surpass 95% ,and the total content ofF and S can drop to around 3%. Therefore,the sludge in the front part can be used as ferric dust. In the calcium salt sludge ,the recovery rate of F can either reach or surpass 85% ,and the total contents of Fe,Cr and Ni can fall below 0.5%. So the sludge in the rear part can be used as fluorgypsum or fluorite. Meanwhile,the results of the analysis on heavy metals leaching toxicity and morphologic distribution indicate that the two kinds of sectionalized sludge are not classified as hazardous wastes, which have a stable behavior and better utilization values compared with the former mixed- sludge.

A new cold rolling lubrication method combining emulsion and neat oil lubrication

The cooling and lubrication process is one of the key processes in cold rolling,as it not only determines surface quality and strip shape,but also reduces the rolling power consumption and extends the life of the roll even during high-speed operation.In this study,an innovative method combining emulsion lubrication and neat oil lubrication was used to solve some problems associated with individual passes.Laboratory tests on stainless steel strips showed that this new lubrication method could improve the surface quality of the strip,control the rolling friction in the deformation zone,and has the potential of making lubrication systems simpler and easier to operate,all while reducing the negative environmental impact from emulsion processing.

Improving emulsion odor in cold rolling production

This paper describes the formation mechanism and mode of the emulsion odor of the cold rolling process,and introduces the relevant environmental regulations and methods used to measure the emulsion odor.Studies were conducted with respect to these issues.The technical measures used to minimize the emulsion odor,particularly the adjustment of the chemical formula of the cold rolling emulsion,are illustrated in detail.The study results have been successfully applied in cold rolling production,and a significant reduction in the emulsion odor is achieved.

Research and practice on the vacuum filter in emulsion system for tandem cold strip mill

This paper introduces working principle and technical features of vacuum filter in emulsion system for tandem cold strip mill.Based on specific cases,this paper analyses and assesses the effect before and after using the emulsion system with the usage of the vacuum filter for strip mill.Compare with the effect when using the first generation vacuum filter,the emulsion quality is improved significantly by using the second generation vacuum filter,which at the same time ensures steady operation of the rolling mill and surface quality of the mill products. As a result,investment and running costs are lowered,emissions of the waste emulsion are reduced,waste water treatment costs are reduced and so as the environmental pollution.It can be seen the second generation vacuum filter has obvious economic and environmental benefits.Therefor,it suggests that the filter should be used widely in the field of automotive,environmental protection rolling steel and nonferrous metals.

Micro Crack of Aluminum Sheet During Cold Rolling

The micro crack of aluminum sheet during cold rolling lubricated with emulsions is investigated. Experi-ments show that micro cracks occur after cold rolling process and this is attributed to various parameters, for instance, the thin oxide film formed at the sheet surface. The micro crack spacing thus becomes an important parameter which deserves more concerns. The aspect ratio of these micro cracks is then analyzed theoreti-cally, which takes into consideration of the oxide fracture process. The good agreement between the obser-vations and the theoretical predictions validates the analysis. The approach can shed some new lights on the mechanical process of aluminium sheet during cold rolling.

Analysis of formation causes for "oil-burn" defects and control measures during cold rolling of silicon steel

It has been found through analysis of defect components and micrographs that ＂oil-burn＂ defects on non- oriented silicon steel surf＇aces, which of ten occur after cold rolling, are composed of Fe, O, Si and C. This study analyzed the fomation mechanism of ＇toil-burn＂ defects and the strategies to prevent them,and proposed, according to the equipment and process status in the production fields ,some relevant optimized control measures and process adjustment schemes from two perspectives of reducing the residual emulsion trod avoiding the specific temperature range. The results demonstrate that the application of the proposed optimization meastu＇es effectively inhibits the formation of ＂oil-bum＂ defects.

New Integrated Processes for Treating Cold-Rolling Mill Emulsion Wastewater

Two new integrated processes, gas-energy-management （GEM）—electrochemical catalytic oxidation （ECO）—membrane bioreactor （MBR） and ultrafiltration （UF）—ECO—MBR, in industrial-scale test for treating cold-rolling mill emulsion wastewater with water quantity of 200 L/h to 3000 L/h were studied. The former was put forward firstly and the latter was applied initially in this field. The operation conditions and mechanisms of each module in the integrated processes were analyzed and the influences of operational parameters of two processes on chemical oxygen demand （CODCr） removal efficiency were comparatively investigated. The test results showed that the ultimate water quality from the two processes after treatment could meet the requirement for reuse.However, the quality of effluent treated by GEM—ECO—MBR was more stable than that of UF—ECO—MBR.

钢厂冷轧硫酸酸洗废水中试实验研究

针对某冷轧厂产生的硫酸酸洗废水,分别采用单一离子交换工艺、单一纳滤工艺和离子交换-纳滤组合工艺将酸洗水处理为脱盐水回用。以电导率为检测指标,探究三种工艺铁离子和硫酸根离子的去除效果。试验结果表明:投加氢氧化钡可以同时达到去除铁离子和硫酸根离子的目的,离子交换+纳滤组合工艺为最优工艺,离子交换前置纳滤工艺可以有效提高离子交换运行周期,最终产水电导率为3μS/cm,符合脱盐水回用标准。

冷轧单机架轧机电工钢表面乳化液残留分析及控制

针对电工钢冷轧带钢表面乳化液残留质量缺陷的增多,进行现场跟踪。通过调试修改工艺参数,以提高设备工作效率;更换老化的设备管路,以减少“跑、冒、滴、漏”造成的污染乳化液;增设压缩空气吹扫装置,以提高吹扫系统的能力;加装防溅板,以降低吹扫难度等,乳化液残留面积明显减少,乳化液斑得到了解决,提升了带钢表面质量,降低了油耗。

不锈钢冷轧高氮高盐废水处理集成技术的研究应用

不锈钢冷轧废水因总氮含量高、离子成分复杂、水质波动大,成为钢铁行业废水处理的技术难题。本文研制了“多段污泥+碳源互补A+多级曝气氧化O”的高效脱氮生化处理工艺,开发了柔性化智能精准调控模型,以构建一种高氮高盐废水脱氮降盐处理的集成技术,为行业废水处理提供一条新途径。同时,结合某冷轧废水脱氮处理的改造开展了应用,结果表明,总氮和盐分去除率分别可达98%和25%以上,与现有工艺对比,本技术脱氮处理效率达到最高,且吨氮处理占地面积、建筑面积和投资成本降至最低,具有良好的经济效益。

冷轧酸洗高氮废水处理中碳源选择的工程应用研究

探讨冷轧酸洗高氮废水处理中碳源选择的工程应用,评估不同碳源的性能,确定最适合处理高氮废水的碳源,并比较其处理成本和安全性。研究采用复合碳源,由多种单一碳源组成。研究结果表明,复合碳源在处理高氮废水方面表现出色,相较于甲醇,其处理成本更低、安全性更高。在试用期间,工艺参数和水质指标均稳定达标,证明了应用复合碳源的可行性和有效性。

不锈钢冷轧酸洗废水资源化技术实验研究

不锈钢冷轧酸洗过程中产生大量高浓度混酸废水,常规处理方法是将混酸废水排入废水处理厂,通过石灰中和法处置废水,但该方法对环境以及企业成本都造成了极大的压力。为此,研究了一种处置该类废水的新工艺。新工艺着眼于将高浓度混酸废水分段分离酸,实现各类酸的回收利用,同时通过工艺分阶段分离,实现高品位铁渣、铬(镍)渣、石膏渣的分类提取,使处置尾渣具备资源回收价值:铁渣、铬(镍)渣可以作为原料回用于炼钢厂,石膏渣可以作为建材回收利用,从而最终实现将无价值的酸性废水转化为有价值的资源,在环保达标的前提下,真正实现酸性废水资源化利用。

无机陶瓷膜处理冷轧乳化液废水

１前言在钢铁厂，为了消除带钢冷轧时产生的变形热，常以乳化液作润滑、冷却剂。乳化液主要由２１０％的矿物油或植物油、乳化剂和水组成。由于乳化液因水分受热蒸发，使盐含量增加、稳定性降低，也会因氧化或细菌作用而变质，所以要连续排出一部分老的乳化液，补充新的乳...

板带钢冷轧乳化液稳定性与润滑性研究

研究了影响乳化液稳定性的几个因素,包括乳化液的HLB值、乳化剂的种类与复配类型、乳化剂的用量及乳化剂化学结构与基础油的相似程度等。结果表明,乳化液的HLB值等于油品被乳化所需的HLB值,乳化剂总量占12%～15%,所选乳化剂的HLB值越接近乳化液的总体HLB值,且其化学结构与基础油的结构越相似,乳化液的稳定性越好;乳化液的均一性与乳化液的总体稳定性具有一致性;在一定的范围内,乳化液的稳定性越好,润滑性能越差。

冷轧乳化液废水处理方法及应用

对某钢铁公司油含量6200mg/L、COD含量34000mg/L的冷轧乳化液废水处理进行研究。通过试验选定有机破乳剂SYS和聚合氯化铝联合破乳,二级破乳后油去除率99.58%,COD去除率97.79%。考察破乳剂投加量、破乳时间、搅拌强度、pH等对破乳效果的影响,确定了二级破乳的最佳运行条件。采用隔油-破乳-气浮-过滤处理工艺,出水达到国家污水排放二级标准。

钢冷轧乳化液稳定性及对冷轧润滑的影响

研究了影响不同类型乳化液稳定性的因素,包括乳化剂的比例和总含量对阴离子乳化油稳定性的影响,乳化剂的HLB值(Hydrophile Lipophile Balance)和总量对非离子乳化油稳定性的影响.研究发现乳化剂的比例和乳化剂的HLB值对乳化油和乳化液的稳定性影响明显.通过研究不同浓度下乳化液的稳定性对其吸附性和摩擦系数的影响发现:乳化液的稳定性在一定范围内时,其润滑效果可达到最佳.在冷轧实验中也发现:应根据冷轧的实际规程和要求来选择乳化液的稳定性和合适的含量,以便使冷轧高效正常地进行.

冷轧乳化液中纳米铁粉的回收

报道了从冷轧乳化液的磁过滤产物中回收纳米铁粉的一种新方法。该方法是经过预处理、清洗除油、漂洗及低温干燥4个步骤完成的,通过试验确定了洗涤次数为3次且每次最佳清洗时间分别为128,35,35min,漂洗次数为4次等条件,回收的纳米铁粉粒度在50～100nm之间,洁净率为96.11%。

纳米添加剂对板带钢冷轧乳化液润滑性能的影响

通过四球摩擦学试验分析纳米添加剂对板带钢冷轧乳化液摩擦学性能的影响;在不同润滑条件下进行冷轧试验,分析纳米添加剂对冷轧过程和轧后带钢表面质量的影响。结果表明,含纳米添加剂的轧制乳化液与传统轧制乳化液相比,其承载能力和抗磨减摩性能均有所改善;带钢冷轧过程中采用含纳米添加剂的轧制乳化液进行润滑,可有效降低轧制压力和轧机功率、减少能耗,并且轧后带钢表面质量也有明显改观。