Manganese toxicity in children receiving long-term parenteral nutrition

BACKGROUND: In patients receiving long-term parenteral nutrition (PN), cholestatic disease and nervous system disorders have been associated with high blood concentrations of manganese. In such patients, the normal homoeostatic mechanisms of the liver and gut are bypassed and the requirement for this trace element is not known; nor has it been certain whether hypermanganesaemia causes the cholestasis or vice versa. We explored the direction of effect by serial tests of liver function after withdrawal of manganese supplements from children receiving long-term PN. We also examined the relation between blood manganese concentrations and brain lesions, as indicated by clinical examination and magnetic resonance imaging (MRI). METHODS: From a combined group of 57 children receiving PN we identified 11 with the combination of hypermanganesaemia and cholestasis; one also had a movement disorder. Manganese supplements were reduced in the first three and withdrawn in the remainder. MRI was done in two of these children. We also looked at manganese concentrations and MRI scans in six children who had received PN for more than 2 years without developing liver disease. FINDINGS: In the hypermanganesaemia/cholestasis group, four of the 11 patients died. In the seven survivors baseline whole-blood manganese was 615-1840 nmol/L, and after 4 months it had declined by a median of 643 nmol/L (p < 0.01). Over the same interval total bilirubin declined by a median of 70 mumol/L (p < 0.05). Two of these children had movement disorders, one of whom survived to have an MRI scan; this showed, with T1 weighted images, bilateral symmetrically increased signal intensity in the globus pallidus and subthalamic nuclei. Such changes were also seen in five other children--one from the hypermanganesaemia/cholestasis group and four of six in the long-term PN group without liver disease (in all of whom blood manganese was above normal). INTERPRETATION: The cholestasis complicating PN is multifactorial, but these results add to the evidence that manganese contributes. In view of the additional hazard of basal ganglia damage from high manganese levels in children receiving long-term PN, we recommend a low dose regimen of not more than 0.018 mumol/kg per 24 h together with regular examination of the nervous system.     

Manganese toxicity in serumless dissociated mesencephalic and striatal primary culture

Exposure to elevated levels of Manganese (Mn) can result in an irreversible brain disease characterized by extrapyramidal signs and symptoms resembling Parkinson's disease. To identify the neuronal target of Mn neurotoxicity, MnCl2 was added to serumless dissociated mesencephalic-striatal cultures from rat embryo on day 4 in vitro. High affinity 3H-dopamine (DA) and 14C-GABA uptakes were assessed as specific functional markers of DAergic and GABAergic cell viability, respectively. After 60-min exposure, MnCl2 at 0-200 microM did not modify the morphologic appearance of the cultures, specific DA and GABA uptakes, or the number of DA neurons visualized by immuno-cytochemical staining with tyrosine hydroxylase. In contrast, culture exposure to 20 microM MnCl2 for 24 h selectively reduced specific GABA uptake without affecting specific DA uptake or the number of DA neurons. The exposure to a higher MnCl2 concentration was accompanied by signs of general toxicity. Striatal GABA neurons seemed to be more susceptible to Mn toxicity than mesencephalic GABA neurons. Overall, our data suggest that striatal neurons rather than mesencephalic DA neurons may be the main target of Mn neurotoxicity.     

由生产高锰酸钾过程中产生的锰泥制取碳酸锰

本文提出了用轧钢废酸处理高锰酸钾生产过程中产生的废渣—锰泥—制取工业级碳酸锰的方法。其流程可分为三段:（1）还原浸出与沉铁;（2）浸出液的净化;（3）工业级碳酸锰的制备。 在第一段中,只要控制好轧钢废酸中的[H⁺]/[Fe²⁺]比就可使浸出、沉铁同时进行,使沉铁的碱用量大大减少,加Na₂S除去浸出除铁液中其它重金属。用NH₄HCO₃制取MnCO₃避免水中Ca²⁺带入MnCO₃。所得碳酸锰符合工业级碳酸锰部颁标准的要求。     

分段浸出氧化锰矿和碳酸锰矿工艺研究

对氧化锰矿与碳酸锰矿浸出相结合的分段浸出工艺进行研究。考察硫酸浓度、葡萄糖用量、反应温度、时间和液固比等对两段锰浸出率及浸出液余酸的影响。结果表明,在还原浸出氧化锰矿阶段,采用葡萄糖占氧化锰矿的质量比6.33%、硫酸浓度4.37 mol/L、液固比1.5、90℃反应3h,锰浸出率为93.7%;在第二浸出阶段,加入剩余阳极液及1.5倍氧化锰矿质量的碳酸锰矿,在液固比6、90℃继续反应3h时,总锰浸出率达96.1%,浸出液余酸值降为9.4g/L。     

Manganese nitrides

Conclusions An investigation was carried out into the kinetics of the process of formation of manganese nitrides in nitrogen and ammonia streams. It was established that the rate of formation of manganese nitrides is higher in ammonia than in nitrogen. The kinetic parameters of manganese nitride formation were calculated.It is shown that in nitrogen the only manganese nitride that can be synthesized in the pure form is Mn_N. In ammonia, depending on the temperature and duration of the nitriding process, it is possible to obtain Mn_N, Mn₂N, and Mn₃N₂ in the pure form, free from any other phases.A study was made of the chemical stability of manganese nitrides of compositions Mn₄N and Mn₃N₂ in water and in concentrated and dilute mineral acids. It was established that these two nitrides are stable in water. In mineral acids they dissolve, the rate of dissolution being higher in concentrated than in dilute acids. In nitric acid Mn₄N and Mn₃N₂ decompose with the liberation of part of the nitrogen in molecular form.Translated from Poroshkovaya Metallurgiya, No. 3(171), pp. 65–70, March, 1977.     

液相氧化法从海底锰结核中浸出锰

开发了液相氧化法处理海底锰结核的工艺，并对结核中锰的浸出进行了研究。初步实验结果表明：该工艺在技术上是可行的，在一定温度、空气流量及碱矿比条件下，锰结核中的锰大部分能被从结核中浸出。通过对结核中锰浸出率的各影响因素的考察，提出了液相氧化法从海底锰结核中提取锰的适宜工艺条件。该工艺不仅适用于浸出海底锰结核，还可应用于陆地相似金属矿的处理。     

锰矿石中的锰物相分析

锰矿石中锰的物相分析是基于各种形式的锰在某种溶剂中溶解度不同这一性质来逐个分离，然后分别进行测定的一类特殊分析方法；锰矿石中锰的物相分析是深入研究有用矿物组成的重要手段。     

锰行业废水中锰排放量核算方法

研究了锰行业废水中锰排放的两种核算方法,即实测法和物料衡算法,确定了废水中锰排放量核算方法的使用原则,并应用两种核算方法对一家电解锰生产企业进行了核算实证。该核算方法适合于锰行业废水中锰排放的核查核算。     

从低锰镁质量比溶液中结晶分离锰、镁试验研究

针对两矿法浸出软锰矿获得的富镁硫酸锰浸出液(锰镁质量比为2.55∶1),研究了采用蒸发结晶法分离锰、镁。通过正交试验和单因素试验,考察了温度、保温时间、搅拌速度对锰结晶行为的影响。试验结果表明:结晶温度、保温时间对硫酸锰晶体纯度影响较大,而搅拌速度对晶体纯度影响较小;低锰镁质量比溶液比高锰镁质量比溶液的结晶分离更为困难。     

硫铁矿-木炭湿法浸出高铁氧化锰矿的研究

针对两矿法浸出高铁氧化锰矿存在生成大量单质硫并覆盖在矿物颗粒表面,降低了反应速率的问题,研究采用在浸出过程中添加木炭粉的方法吸附单质硫以改善浸出效果。考察了木炭粉添加量、硫铁矿用量、硫酸浓度、浸出温度和浸出时间对高铁氧化锰矿中锰浸出率的影响。在高铁氧化锰矿用量10.0g、硫铁矿用量5.0g、木炭粉添加量0.1g、硫酸浓度1.36mol/L、浸出温度70℃和浸出时间4h的条件下,锰浸出率达到96.7%。     

蔗糖还原浸出锰阳极泥中锰的研究

采用蔗糖还原浸出阳极泥中的锰,通过正交实验和单因素实验,探讨了搅拌速率、液固比、反应温度、反应时间、硫酸浓度、蔗糖浓度等因素对阳极泥锰浸出率的影响,正交实验表明,各因素影响锰浸出率的大小顺序为:硫酸浓度蔗糖浓度浸出温度浸出时间。较优的工艺条件为:硫酸浓度3.5 mol/L,蔗糖浓度70 g/L,液固比为4∶1,搅拌速率100 r/min,反应温度70℃,反应时间40 min,锰浸出率达到98%。     

高硫碳酸锰矿与软锰矿直接浸出实验

传统电解锰生产中,软锰矿需要经过还原焙烧将其中的Mn4+还原为Mn2+才能被稀硫酸浸出制得MnSO4溶液。利用高硫碳酸锰矿中的硫铁矿成份和浸出时产生的具有还原性的H2S和溶液中的Fe2+,可以直接浸出软锰矿中的Mn4+。经过多次实验对比,总结出了较理想的高硫碳酸锰矿与软锰矿的配矿比,既有利于高硫碳酸锰矿在浸出时产生的H2S的利用吸收,减少尾气中的H2S,给尾气处理减轻负担,又有利于保持较高的浸出率,可为高硫碳酸锰矿和软锰矿的直接浸出提供参考。     

锰铁高炉喷吹自产锰尘的探讨

根据国内外高炉喷矿技术的进展和新钢公司锰尘利用的实际情况，对锰铁高炉喷吹自产锰尘进行了探讨。     

用电解锰阳极液制备电池级硫酸锰

研究了采用一种新型萃取剂A从电解锰阳极液中通过溶剂萃取获得制备电池级硫酸锰的高纯溶液,考察了振荡时间、水相pH、萃取剂浓度、有机相皂化率、相比Vo/Va、硫酸铵浓度对萃取的影响,以及相比Vo/Va和酸度对反萃取的影响.结果表明:在Vo/Va=1.5/1、萃取剂体积分数30％、有机相皂化率30％、水相pH=4.6、25℃条件下萃取15 min,锰萃取率为77.9％,镁萃取率为13.7％;用1 mol/L硫酸溶液,在相比V o/V a=6/1条件下反萃取负载有机相,得到平均锰质量浓度53 g/L、酸度较低的反萃取液;用此反萃取液制得的硫酸锰产品中锰质量分数大于32％,镁质量分数低于1.5×10-5,符合化工行业《电池用硫酸锰》一等品要求.     

用贫碳酸锰矿制备工业硫酸锰的工艺研究

介绍了以贫碳酸锰矿为原料,采用硫酸直接酸浸法制备工业级硫酸锰的工艺流程,详细讨论了影响锰浸出的各种因素。试验结果表明:在酸矿比为0.45、浸出温度为90℃、反应时间为4 h、液固比为4∶1和转速为300 r/min条件下,锰浸出率高达97.44%。浸出液经净化除杂、浓缩结晶后,得到纯度为98.3%的工业级硫酸锰产品。     

广西大新锰矿碳酸锰矿产资源的开发利用

通过分析广西大新锰矿当前矿山生产经营情况和氧化锰矿保有地质储量逐年减少的趋势,以及对碳酸锰矿地质条件及其矿石可选性试验研究的探讨,论述了开发利用碳酸锰矿的可行性和必要性。     

电解锰渣回收锰制备高纯硫酸锰的研究

利用二氧化锰矿粉和硫酸的氧化作用浸出锰金属,再通过调节浸出液pH除大部分的铁,然后在不同pH条件下采用P204萃取剂两步法除钙铁和回收锰,最后经硫酸反萃取后浓缩结晶制备高纯硫酸锰。最佳工艺条件为:在硫酸浓度100g/L、液固体积质量比6mL/g、渣料质量比8、浸出温度90℃、浸出时间180min,锰浸出率可达93.5%;调节浸出液pH=4.0除大部分的铁,除铁率达到了84.8%,溶液浓缩定容至20mL,调节浸出液pH=1.6,加入体积比1∶1、皂化率30%的P204和磺化煤油萃取剂,萃取10min,钙、铁萃取率分别达到了91.2%和80.5%,再次调节浸出液至pH=3.5,加入体积比2∶1、皂化率30%的P204和磺化煤油萃取剂,萃取10min,锰萃取率最高达92.9%,最后经硫酸反萃取后浓缩结晶制备高纯硫酸锰,锰的总回收率达到了82.6%,溶液经浓缩结晶后得到的高纯硫酸锰纯度达到了99.78%,含铁0.0012%、钙0.0023%。     

进口锰矿在电解金属锰生产中的应用前景

简要概述了国内锰矿资源的分布和特点,从矿产资源量、品位和经济效益3个方面分析了国内锰矿不能满足电解金属锰生产的现状,并指出了进口锰矿在电解金属锰生产应用中的优势与前景。     

乌克兰碳酸锰矿制取电解金属锰的研究

对乌克兰碳酸锰矿制取电解金属锰,进行了浸出、净化、电解全流程的理论分析与试验研究.获得了良好的试验结果与满意的技术指标.     

锰阳极泥回收制备硫酸锰工艺研究

以电解法生产金属锰产生的阳极泥为原料,比较和优化了两种以木屑还原锰阳极泥浸出高纯硫酸锰的制备工艺。结果表明,优化工艺利用浓硫酸的稀释热快速水解木屑并还原锰阳极泥中的二氧化锰,对产自湖北某电解厂的锰阳极泥的锰浸出率可达99.5%以上,回收率达98%。