废盐酸再生工艺浅析

介绍了Ruthner-喷雾焙烧法和Lurgi-流化床焙烧法两种废盐酸再生技术,对比了两种工艺的特点,并进行了评析.     

盐酸再生改进工艺运行分析

阐述了盐酸再生工艺的基本流程,对此工艺进行了改进,使之能够实现对洗涤塔和除尘文丘里内的循环介质的连续更新,避免其出现过浓缩现象,并且可将更新后排出的介质用于对再生酸的吸收。分析了在盐酸再生系统的实际运行过程中的工作状态及运行参数,确认该系统得到优化改进。     

钢铁企业酸再生工艺的研究

介绍了酸洗废液再生处理的几种方法及国内大型钢铁企业目前使用的酸再生系统,分析了酸再生技术的优点,该技术具有很强的使用价值,值得在国内钢铁企业中推广。     

废盐酸再生装置焙烧炉内衬砌筑与烘烤

介绍废盐酸再生装置焙烧炉内衬筑材料技术性能，砌筑施工和炉料烘烤的实用技术。     

冷轧酸再生“红烟”产生原因分析及防范措施

对冷轧酸再生在酸操作切换到漂洗水操作过程中产生＂红烟＂的原因进行分析,介绍了现场采用新的酸操作至漂洗水操作的切换工艺,最终使＂红烟＂问题得以解决。     

盐酸法富集低品位锰矿及酸介质高值再生工艺

针对印度尼西亚某低品位锰矿,提出盐酸法富集与酸介质高值再生的工艺。借助X射线衍射分析,光学显微镜和电子显微镜等表征方法进行工艺矿物学分析。结果表明:该锰矿矿物组成简单,主要由方解石、软锰矿和少量菱锰矿、褐铁矿、高岭石等组成。筛析结果显示该锰矿粒度越小,锰含量相对越高。粗碎后以2 mm筛孔的筛子过筛可得到锰质量分数为33.32%的锰中矿。锰中矿盐酸直接浸出的最佳条件为:浸出pH 3.0、浸出时间1.5 h、搅拌转速200 r·min?1、液固比4∶1 mL·g?1,此条件下产出的锰精矿品位为54.50%,钙质量分数为0.57%。常温下盐酸再生可产出二水硫酸钙晶须,其长径比可达50以上。再生盐酸返回浸出锰中矿,产出的锰精矿品位为52.16%,钙质量分数为1.39%,验证了该工艺流程的可行性。X射线衍射分析、扫描电镜及能谱分析结果显示产出的锰精矿主要组成成分为软锰矿,杂质为少量褐铁矿、高岭石等。酸介质循环时杂质将逐渐积累,当镁离子质量浓度积累到96.74 g·L?1时,采用水解沉淀法进行除杂。      

电位滴定法测定Ruthner法盐酸再生工艺流程酸洗液中游离盐酸浓度

采用Ruthner法盐酸再生工艺对酸洗液进行再生处理时,需要及时测定其游离盐酸浓度。当采用通过电位滴定法测定酸洗液中游离H+浓度得到游离盐酸浓度的方法时,酸洗液中Fe²⁺和Fe³⁺的存在会干扰测定。实验利用Ca-CaY(0.1mol/L EDTA-0.150mol/L CaCl₂溶液)作为掩蔽剂消除了酸洗液中大量Fe²⁺和少量Fe³⁺的干扰,实现了电位滴定法对Ruthner法盐酸再生工艺流程酸洗液中游离盐酸浓度的测定。试验结果表明,Ca-CaY掩蔽剂的加入不仅对游离酸的测定无影响,且可使pH值的突跃范围变窄;在采用电位滴定法时,设定终点判断阈值为10、终点判断范围pH=7～10、终点识别为最大,可避免pH=6附近的突跃对终点的影响从而获得准确的滴定终点。优化后确定Ca-CaY掩蔽剂用量为10mL。从Ruthner法盐酸再生工艺不同流程中各取1个酸洗液样品,按实验方法测定游离盐酸浓度,并采用间接法进行方法对比。结果表明,采用t检验验证,t为0.51～1.18,小于t(0.05,9...     

鞍钢酸再生机组盐酸酸雾净化系统改造实践

针对鞍钢股份有限公司冷轧硅钢厂酸再生机组盐酸酸雾净化系统老化、颗粒物和HCl排放超标的问题,对该酸雾净化系统进行了改造,包括更换文丘里设备、增加二级换热器及后文丘里设备,改造后尾气中颗粒物含量<10 mg/m3,HCl含量<15 mg/m3,满足了国家环保要求,同时降低了尾气风机的负荷,延长了尾气风机的使用寿命.     

酸再生工艺参数对氧化铁粉质量的影响

研究了酸再生工艺参数，例如反应温度、浓度酸密度、空煤比、水质等，对副产品氧化铁粉（Ｆｅ２Ｏ３）质量的影响。提出了合理的可以保证氧化铁粉质量的工艺参数。进行了用攀钢冷轧厂氧化铁粉试制磁性材料的试验，结果表明，用这种氧化铁粉生产的永磁体的质量达到或超过了ＳＪ／Ｔ１０４１０－９３标准中的Ｙ３０Ｈ－１牌号。     

酸再生废气排放工艺优化与设备改进

面对日益严峻的环保要求,对酸再生机组废气排放设备存在的问题进行了分析。以酸再生焙烧炉废气温度、酸再生废气中氯化氢水平为重点,分析了废气不达标的原因。通过预浓缩器内废酸浓度工艺优化,增加三级石墨冷凝器等措施,保证了酸再生机组环保稳定性。并对酸再生的改进建议和操作方法进行了详细介绍。     

建筑材料样品密度效应研究

介绍用低本底γ能谱仪对不同密度状态下的建筑材料样品的γ能谱进行测量分析,来确定建筑材料中天然放射性核素的含量与其密度之间的关系;并利用指数函数曲线拟合的方法,来拟合材料密度与探测效率之间的关系曲线.同时对测量的方法、原理、刻度以及测量和分析中存在的一些问题进行了讨论.     

Leaching of pyrrhotite with hydrochloric acid

Abstract

When nonstoichiometric pyrrhotite is leached under nonoxidizing conditions in warm aqueous solutions containing HCl, both hydrogen sulphide and elemental sulphur are formed. The amount of sulphur is proportional to the nonstoichiometry of the pyrrhotite. The leaching reaction is rapid (only seconds required to completion) but, when minimum conditions of acidity and/or temperature are not met, the sulphur coating becomes protective and the reaction ceases. When the reaction is begun rapidly, all of the acid or all of the pyrrhotite will be consumed, depending upon which is in excess. In hydrochloric acid, pentlandite dissolves more slowly than pyrrhotite but chalcopyrite is almost insoluble.

Résumé

A des températures au-dessous de 100°C quand les pyrrhotines de composition non stoichiométriques sont lixiviées par des solutions d'acide chlorhydrique en milieu non-oxydant, les produits de la réaction sont l'hydrogéne sulfuré et le soufre. La quantité de soufre produit est proportionnelle au degré de non stoichiométrie de la pyrrhotine. La réaction est rap ide (question de secondes seulement) mais au-dessous d'un minimum d'acide et de température, la couche de soufre recouvre la surface et la réaction s'arrête. Par contre, si la réaction débute rapidement elle se continuera jusqu’è l'épuisement du réactif minoritaire (HCl ou pyrrhotine). En milieu chlorhydrique la pentlandite se dissout plus lentement que la pyrrhotine, mais la chalcopyrite est très peu soluble.     

Kinetics of hydrochloric acid leaching of smithsonite

The dissolution kinetics of smithsonite ore in hydrochloric acid solution has been investigated. As such, the effects of particle size (−180 + 150, −250 + 180, −320 + 250, −450 + 320 μm), reaction temperature (25, 30, 35, 40, and 45°C), solid to liquid ratio (25, 50, 100, and 150 g/L) and hydrochloric acid concentration (0.25, 0.5, 1, and 1.5 M) on the dissolution rate of zinc were determined. The experimental data conformed well to the shrinking core model, and the dissolution rate was found to be controlled by surface chemical reaction. From the leaching kinetics analysis it can be demonstrated that hydrochloric acid can easily and readily dissolve zinc present in the smithsonite ore, without any filtration problems. The activation energy of the process was calculated as 59.58 kJ/mol. The order of the reaction with respect to HCl concentration, solid to liquid ratio, and particle size were found to be 0.70, −0.76 and −0.95, respectively. The optimum leaching conditions determined for the smithsonite concentrate in this work were found to be 1.5 M HCl, 45°C, −180 + 150 μm, and 25 g/L solid to liquid (S/L) ratio at 500 rpm, which correspond to more than 95% zinc extraction. The rate of the reaction based on shrinking core model can be expressed by a semi-empirical equation as:

Aqueous oxidation of chalcopyrite in hydrochloric acid

The aqueous oxidation of chalcopyrite flotation concentrate is faster in HC1 than in H₂SO₄. Under certain conditions, FeCl₂ formed during reaction undergoes oxidation and hydrolysis (or vice versa) yielding α-Fe₂O₃ or β-FeOOH depending on the initial acidity, O₂ pressure, and temperature. A small fraction of sulfur oxidizes to soluble SO ₄ ^2- and a part precipitates as Fe(OH)SO₄. The precipitation of FeOOH is more enhanced in HC1 than in H₂SO₄ solution. Optimum leaching conditions are 110°C, 2010 kPaO₂, 2 N HC1, molar ratio CuFeS₂/HCl 0.8 to 0.9, and time of reaction 45 min. Under these conditions practically all the iron precipitates and the reaction can be described by the equations: CuFeS₂ + 2 HCl + 5/4 O₂ → CuCl₂ + FeOOH + 1/2H₂O + 2S and CuFeS₂ + HC1 + O₂ → CuCl + FeOOH + 2S. Copper ferrite, CuFe2O₄, precipitates if the final pH of the leach solution is ≥2.2, while CuCl precipitates if the initial acidity is increased to 3 N HC1.     

Extraction kinetics of alunite in sulfuric acid and hydrochloric acid

Extraction kinetics of alunite in sulfuric acid and hydrochloric acid were studied in a batch reactor. The effects of reaction temperature, acid concentration, particle size, calcination temperature, calcination time and KF/Al₂O₃ molar ratio on the extraction process were investigated. Experimental studies were carried out in the ranges of 35–95 °C for reaction temperature, 0.25–3.0 M for sulfuric acid, 0.5–0.6 M for hydrochloric acid, 76–182 μm for average particle size, 100–900 °C for calcination temperature, 15–60 min for calcination time and 0.15–0.90 for KF/Al₂O₃ molar ratio. The calcination temperature was the most important parameter affecting the extraction process followed by reaction temperature, particle size and acid concentration. Others had less effect. It was determined that the extraction process is controlled by diffusion through a product layer. The activation energies of the processes were found to be 19.1 and 18.5 kJ/mol for sulfuric acid and hydrochloric acid, respectively. The apparent rate constants were similar for both acids and found to be a function of acid concentration as C^0.33 and particle size r^−0.8.     

结晶器内磁感应强度分布研究

采用CST—11A型数字特斯拉计对圆坯连铸机结晶器内磁感应强度进行了研究,研究表明:结晶器的磁感应强度随电流的增加而增大,随频率的增大而降低;结晶器内磁感应强度轴向最大位置在距结晶器上口900 mm位置,向两侧陡降;径向分布不均匀,由搅拌器内表面向中心逐渐减小;高频率经结晶器铜管后衰减更大.研究结果对合理制定及优化电磁搅拌工艺参数提供了理论依据.     

Substitution of acetic acid for hydrochloric acid in the bicarbonate buffered dialysate

In a multicenter study including 5 dialysis units, blood acetate changes during 4 h dialysis sessions in 141 patients treated with a 4 mM acetate-containing bicarbonate dialysate (ABD) were evaluated and compared to the values of 114 patients using an acetate-free bicarbonate dialysate (AFD). Acetate-free bicarbonate dialysate was delivered by a dialysis machine from the mixing with water for dialysis of a 1/26.2 bicarbonate concentrate, and a 1/35 acid-concentrate in which acetic acid was substituted for hydrochloric acid (Soludia, Fourquevaux, France). This new type of dialysate was routinely in use for 3 years on average (range, from 2 to 5 years). All patients fasted before and during dialysis. Blood samples were withdrawn at the start and at the end of dialysis sessions. The acetate plasma concentration was determined using the acetyl-CoA synthetase enzymatic method (Boehringer, Manheim, Germany). In patients treated with ABD whose predialysis blood acetate levels were in the physiologic range of < or = 100 microM (n = 113), the acetate plasma concentration increased from a predialysis mean value of 22+/-3 microM to a postdialysis mean value of 222+/-11 microM in 88 patients (78% of patients) whereas the acetate plasma concentration changes remained in the range of physiologic values from 21+/-6 to 58+/-7 microM in the other 25 patients. In contrast, patients treated with AFD whose predialysis blood acetate levels were in the physiologic range (n = 108), acetate plasma concentration increased from a predialysis mean value of 49+/-6 microM to 160+/-19 microM in only 13 patients (12% of patients) whereas acetate plasma concentration changes remained in the range of physiologic values of 23+/-2 to 41+/-3 microM in most of the patients of this group. In this study, a significant number of patients, whether receiving standard or acetate-free bicarbonate dialysates, exhibited an extremely high acetate plasma concentration at the start of the dialysis session. Hyperacetatemia was controlled with AFD in patients whose predialysis acetate plasma concentration of 316+/-82 decreased to 55 +/-23 microM (n = 6) at the end of the dialysis session whereas the acetate plasma concentration remained high when the predialysis concentration was 580+/-76 microM, with a postdialysis concentration of 233+/-39 microM (n = 28). It is concluded that in patients whose predialysis blood acetate levels were in the physiologic range, acetate-containing bicarbonate dialysate induces hyperacetatemia whereas postdialysis blood acetate remains in the normal range in such dialysis patients treated with acetate-free dialysate. Chronic hyperacetatemia, which could be found in dialysis patients, is well controlled by dialysis using an acetate-free dialysate.     

Dewatering sludges from chemically contaminated hydrochloric acid pickling solutions

Energostal' Scientific-Industrial Association. Translated from Metallurg, No. 9, pp. 18–19, September, 1989.