Sulfidation roasting of lead and zinc carbonate with sulphur by temperature gradient method

In order to enhance the lead and zinc recovery from the refractory Pb-Zn oxide ore, a new technology was developed based on sulfidation roasting with sulphur by temperature gradient method. The solid-liquid reaction system was established and the sulfidation thermodynamics of lead and zinc carbonate was calculated with the software HSC 5.0. The effects of roasting temperature,molar ratio of sulphur to lead and zinc carbonate and reaction time in the first step roasting, and holding temperature and time in the second roasting on the sulfidation extent were studied at a laboratory-scale. The experimental results show that the sulfidation extents of lead and zinc are 96.50% and 97.29% under the optimal conditions, respectively, and the artificial galena, sphalerite and wurtzite were formed. By the novel sulfidizing process, it is expected that the sulphides can be recovered by conventional flotation technology.

Senarmontite volatilization kinetics in nitrogen atmosphere at roasting/melting temperatures

The volatilization kinetics of senarmontite（Sb_2O_3） was analyzed in a neutral atmosphere in two temperature ranges： 550-615 °C（roasting temperature） and 660-1100 °C（melting temperature） by using a thermogravimetric analysis method under various gas flow rates and using a 1.3 m L ceramic crucible（11 mm in internal diameter and 14 mm in height）. The effect of particle size was also analyzed. The experimental results of mass loss data, X-ray diffraction（XRD） analysis of partially reacted samples and thermodynamic studies indicate that the senarmontite becomes volatile in the form of Sb_4O_6（g） without the formation of any intermediary compound in the entire temperature range. At roasting temperatures, the volatilization kinetics of Sb_2O_3 was analyzed using the model X=kappt. The volatilization reaction was controlled by the surface chemical reaction and an activation energy value of 193.0 k J/mol was obtained in this temperature range. Based on the volatilization kinetics at the melting temperatures, for linear behaviour in nitrogen gas, kinetic constants were determined, and an activation energy of 73.9 k J/mol was calculated for the volatilization reaction with a surface area of 8.171×10^（-5）m^2.

Prediction of Al(OH)_3 fluidized roasting temperature based on wavelet neural network

The recycle fluidization roasting in alumina production was studied and a temperature forecast model was established based on wavelet neural network that had a momentum item and an adjustable learning rate. By analyzing the roasting process, coal gas flux, aluminium hydroxide feeding and oxygen content were ascertained as the main parameters for the forecast model. The order and delay time of each parameter in the model were deduced by F test method. With 400 groups of sample data (sampled with the period of 1.5 min) for its training, a wavelet neural network model was acquired that had a structure of {7 211}, i.e., seven nodes in the input layer, twenty-one nodes in the hidden layer and one node in the output layer. Testing on the prediction accuracy of the model shows that as the absolute error ±5.0 ℃ is adopted, the single-step prediction accuracy can achieve 90% and within 6 steps the multi-step forecast result of model for temperature is receivable.

Oxidation and roasting characteristics of artificial magnetite pellets

Compared with natural magnetite concentrate, artificial magnetite with more lattice defects and higher activity tends to be oxidized. And the artificial magnetite pellet at the temperature of 400℃ has the oxidation degree approaching to natural magnetite concentrate pellet fired at 1000℃. Besides, two kinds of pellets displayed quite different roasting characteristics. When preheated at the same temperature for the same period of time, natural magnetite concentrate pellet and artificial magnetite concentrate pellet need to be roasted at the temperature of 1100℃ and 1250℃, respectively, for 25 min to reach the compressive strength of 3000 N per pellet. When roasted at the same temperature of 1200℃, natural magnetite pellet and artificial magnetite pellet need to be roasted for 15 min and 30 min, respectively, to reach the compressive strength over 3000 N per pellet. It can be seen from the test that artificial magnetite pellet has a faster oxidation, resulting in the high porosity in the produced pellet, and it requires a roasting process at higher temperature for a longer time to reach the desired compressive strength for industrial production.

Improving vanadium extraction from stone coal via combination of blank roasting and bioleaching by ARTP-mutated Bacillus mucilaginosus

In order to improve leaching efficiency of vanadium from stone coal,the combination of blank roasting and bioleaching using Bacillus mucilaginosus(B.mucilaginosus)mutants was evaluated.The atmospheric and room temperature plasma(ARTP)technique was used to generate B.mucilaginosus mutants.The results showed that a mutant B.mucilaginosus BM-50,after ARTP irradiation for 50 s,had the highest acid production.The total content of the organic acid produced by B.mucilaginosus BM-50 was nearly doubled compared with the wild strain after 2 days.After 20 days,vanadium leaching rate with B.mucilaginosus BM-50 reached 18.2%,which was improved compared with the original bacteria(15.3%).A pretreatment via blank roasting for stone coal further improved the vanadium dissolution by bioleaching,namely,68.3%vanadium was extracted,which was much higher than that without blank roasting.It is shown that bioleaching by bacterial mutants by ARTP irradiation combined with blank roasting has great potential for improving vanadium recovery from low-grade vanadium bearing stone coal.

Sensory Evaluation of Different Packaged Roast Beef Treatments Designed for the Extension of Its Shelf Life

This study was carried out to investigate the effect of different nitrite concentrations on the sensory parameters of roast beef including color, flavor, juiciness, texture and overall acceptability. Four roast beef batches were formulated;the first three treatments were with nitrite concentrations of 0.006%, 0.012% and 0.018% and stored at abused chilling temperature (12°C), while the fourth one was a control treatment with 0.026% nitrite and storage at 4°C. Results showed that increasing nitrite concentration from 0.006% to 0.026% enhanced the shelf life of roast beef stored for 7 days without affecting the sensory characteristics whether at 12°C or 4°C since there were no significant differences (P > 0.05) between all treatments regarding color, flavor, juiciness, texture and overall acceptability. These results could direct us to use high nitrite concentration to protect this product and elongate its shelf life without affecting its preference parameters.

Evaluation of the Shelf Life of Packaged Roast Beef and Some Treatments for Its Extension

This study was carried out to investigate the effect of nitrite concentration, and abused chilling temperature against proper chilling temperature on the chemical, microbiological and shelf life of roast beef stored at 4°C and 12°C. Three roast beef treatments were formulated to investigate the effect of nitrite concentration (0.006%, 0.012% and 0.018%) and abused chilling temperature (12°C) against control treatment (0.026% nitrite and storage at 4°C) on the chemical, microbiological and shelf life. Results showed that roast beef containing 0.026% nitrite and stored at 4°C for 25 days had the lowest thiobarbituric acid (TBA) value while the highest TBA values were in the treatment containing 0.006% added nitrite, stored at 12°C. The aerobic plate count, Enterobacteriaceae, lactic acid bacteria (LAB), and spore former count were increased throughout the storage period which was lower in 0.026% and 0.018% containing nitrite treatments while higher in other two treatments. The lowest percentage of nitrite losses during storage was in the samples having 0.026% added nitrite to roast beef. The results emphasized the risk of abused temperature and the importance of keeping this product under efficient and consistent refrigeration during storage and the use of high nitrite concentration to protect it and elongate its shelf life.

某低品位黏土型锂矿石的焙烧——无酸浸出试验研究

云南某低品位黏土型锂矿石含锂0.147%,为探究低能耗、环保的开发利用工艺,采用新型焙烧助剂ASH开展了低温焙烧—无酸浸出的提锂工艺研究,并结合XRD、SEM-EDS等分析手段阐述了反应机理。试验结果表明,在试样与ASH质量比为1∶0.3、焙烧温度为400℃、焙烧时间为1.0 h,去离子水浸出时间为2 h、浸出温度为70℃、液固比为5 m L/g条件下,锂浸出率为83.81%。机理分析显示,焙烧—浸出前后,样品中主要矿物相未发生变化,但衍射峰强度降低;经焙烧—浸出后,浸渣表面均匀分布着裂纹和空隙,Al、Si、Fe、Ti含量均有所降低。说明ASH与矿物发生反应,破坏了矿物的表面结构,生成了可溶性盐Li-ASH。与传统焙烧—浸出工艺相比,本研究所采用的提锂工艺焙烧温度低、浸出时无酸,降低了生产能耗、简化了工艺流程,对同类型低品位黏土型锂矿的绿色高效开发利用具有重要借鉴意义。

铁矿氧化球团低温还原粉化性能的影响因素评述

在高炉和气基竖炉工艺中,为使炉况良好,应保证上升还原气能快速且均匀地穿过料柱,而含铁炉料的低温还原粉化和还原膨胀是恶化料柱透气性的两大主要原因.本文主要综述了影响铁矿氧化球团低温还原粉化性能的因素,并在此基础上讨论了改善球团矿低温还原粉化性能的主要措施.影响球团矿低温还原粉化性能的主要因素包括:球团矿的化学成分(碱度、SiO_(2)、MgO、Al_(2)O_(3)含量等)、物相组成、微观结构和碳沉积等.在实际生产中,可以通过优化球团矿成分(适当提高碱度或MgO含量等)和固结形式(发展部分液相固结)、调控球团矿孔隙结构(喷洒或涂层降低球团孔隙率)等来降低还原速率,减少还原过程产生的内应力,从而改善球团矿的低温还原粉化性能.

CO优先氧化反应MnCu/Ce催化剂的制备及性能

采用共浸渍法制备较低Cu含量的MnCu/Ce催化剂,通过XRD、BET、H_(2)-TPR、XPS和CO_(2)-TPD等表征手段对催化剂进行表征,考察催化剂焙烧温度对催化剂结构、性质及其在含有CO_(2)的富氢气氛下对CO优先氧化性能的影响。结果表明,MnCu/Ce催化剂均有Cu/Mn-O-Ce固溶体形成,其中,在焙烧温度600℃制备的催化剂中,Mn与Cu、Ce之间相互作用较强,形成较多三元氧化物固溶体,氧空位/Ce^(3+)含量高,具备良好的CO-Prox活性。此外,对反应条件的考察发现,添加不同分压Ar对催化剂的CO-Prox活性影响较小,气体空速和氧过量系数对催化剂活性影响较大,且反应原料气中CO_(2)的存在对CO-Prox反应有负面影响。氧过量系数为1.2、空速范围为20266-30400 mL/(g·h)时,CO转化率最高,达到94.7%。

球团配加钒钛磁铁精矿试验研究

为充分利用哈密地区钒钛磁铁精矿,进行了配加钒钛磁铁精矿球团试验及球团矿冶金性能试验。试验结果表明:钒钛精矿球团生球爆裂温度均大于600℃,可满足竖炉生产要求;与普通精矿相比,钒钛磁铁精矿需要更高的焙烧温度,本次试验将焙烧温度提高了50℃左右,但球团矿抗压强度仍略偏低;成品球团矿还原膨胀率在8.19%~12.09%;成品球团矿900℃还原度在54.50%~63.20%。

不同品种核桃仁成分及烘烤对其油脂品质和内源性蛋白酶活性的影响

旨在为工业去衣核桃仁的烘烤处理条件提供参考,选择我国4个品种核桃仁作为研究对象,比较了4种核桃仁的蛋白质和脂肪含量,分析了其氨基酸和脂肪酸组成,并考察了烘烤(60~140℃烘烤1~3 h使水分含量降至5%以下)对这4种去衣核桃仁油脂品质及内源性蛋白酶活性的影响。结果表明:核桃仁蛋白质(13.73%~17.54%)、脂肪(69.10%~72.77%)含量及其油脂亚麻酸含量(8.77%~13.23%)在品种间存在显著性差异(p<0.05),而氨基酸组成未表现出明显差异;随着烘烤温度的升高,4种去衣核桃仁油脂的酸值及过氧化值均呈现不断上升的趋势,但均未超过国家标准要求;未烘烤核桃仁内源性蛋白酶活性在品种间也存在显著性差异(p<0.05);烘烤温度对核桃仁内源性蛋白酶活性有显著影响,60~80℃烘烤尚且保留了大部分的内源性蛋白酶活性,而100~140℃烘烤核桃仁内源性蛋白酶活性大幅度下降甚至丧失。综上,烘烤对去衣核桃仁油脂及内源性蛋白酶的影响并不因核桃品种的不同而产生差异,60~80℃的烘烤适合生产高内源性蛋白酶活性的去衣核桃仁(坚果类产品)。

高效空气源热泵式烤房优化设计

针对普通燃煤烤房能源消耗大、污染环境和生物质燃料烤房存在较大的安全隐患等问题,对普通烤房进行改造,引入空气源热泵系统,利用流体力学软件FLUENT对烤房不同气流形式结构、装烟室地面分风坡结构、加热室底部导流板结构的烘烤过程进行数值模拟,以获得烘烤性能最优的烤房结构形式;同时对温湿度控制系统进行设计,以实现烤房温湿度的精准调控,最后开展节能应用效果和温湿度操控性能正交试验。试验结果表明:所设计的空气源热泵烤房与普通燃煤烤房和生物质燃料烤房相比,能源消耗减少,平均烘干1 kg烟叶可分别节约0.77元和0.35元,烟农节能增收成效显著;在温湿度调节上更加准确灵敏,烟叶烘烤质量明显提高。

烘烤温度影响油莎豆出油率及品质的机理研究

以油莎豆为原料,从蛋白质二级结构、细胞结构和油脂体粒径角度探究烘烤温度对油莎豆出油率影响机理,并分析烘烤温度对油莎豆油理化性质、脂肪酸组成及含量、氧化稳定性和流变特性影响。结果表明:烘烤温度的改变对油莎豆出油率有显著影响(P<0.05),提高了2.06%~3.58%。在90~150℃烘烤温度范围内,随着温度的升高,油莎豆蛋白二级结构由α-螺旋和β-折叠的有序结构向无规则卷曲和β-转角的无序结构转化,导致油脂脱离束缚,同时细胞结构受到破坏,促进油脂聚集和流出,油脂体由小油滴聚集成大油滴或连成片状结构。随着烘烤温度的升高,油莎豆油酸价和过氧化值增加,氧化初始温度和黏度显著升高,但对油莎豆油脂肪酸组成和含量影响较小,无显著性差异,所测指标均在国家标准范围内。烘烤温度为120℃时,油莎豆蛋白质二级结构松散、破碎的细胞壁最薄、油脂体粒径最大,出油率最高,达到24.02%,且具有良好的油品质。本研究有助于阐明烘烤温度对油莎豆出油率的影响机理,以期为油莎豆油的高值化利用提供指导。

CaO和Na_(2)SO_(4)对α-锂辉石一步焙烧提锂过程的矿相调控

当前锂辉石提锂工艺主要采用高温转型—硫酸化焙烧法,通常需要1100℃左右转晶焙烧及硫酸化焙烧工序,存在能耗高、工艺流程长等问题。提出了一种以CaO和Na_(2)SO_(4)为混合助剂的一步低温焙烧法从α-锂辉石提取锂的工艺,进一步优化了助剂用量及焙烧温度。结果表明:在焙烧温度900℃、焙烧时间2 h,50%Na_(2)SO_(4)和6%CaO混合助剂作用下,锂浸出率达94.97%。借助XRD、FT-IR、SEM-EDS等分析方法明确了混合助剂对α-锂辉石一步焙烧提锂过程的矿相调控机理为:CaO在低温可与α-锂辉石反应生成钙长石及石英,破坏锂辉石的稳定结构,降低了α-锂辉石转型温度,Na_(2)SO_(4)与石英、锂辉石进一步反应生成钠长石和可溶性NaLiSO 4。该工艺显著降低了锂辉石的焙烧温度,实现了锂的短程高效提取,具有重要的应用价值。

电解锰渣中温焙烧无害化处理

电解锰渣产量大、含污染性物质,当前处理方式主要为渣库堆存,带来一定的安全环保隐患,制约我国锰产业的高质量发展。为开发电解锰渣无害化处理工艺,分别采用直接焙烧和添加碱性添加剂协同中温焙烧工艺处理电解锰渣,系统考察了焙烧温度、焙烧时间、添加剂掺入量等因素对焙烧渣水溶锰、水溶性盐、氨氮、有机质含量的影响。结果表明,直接焙烧时,焙烧产物中水溶锰、水溶性盐含量仍较高,氨氮、有机质明显降低;掺入碱性添加剂焙烧时,水溶锰、水溶性盐固化及氨氮、有机质脱除效果显著,在焙烧温度600℃、焙烧时间100 min、碱性添加剂掺入量为10%的最佳条件下,焙烧样中水溶锰为0.21μg/L、水溶性盐质量分数为1.91%、氨氮含量为3.36 mg/L、有机质为1.95%,达到《一般工业固体废物贮存和填埋污染控制标准》(GB 18599—2020)中对进入Ⅰ类堆场的一般工业固体废物要求。电解锰渣直接中温焙烧难以实现无害化,掺入碱性添加剂中温焙烧后可实现无害化处理。本研究对降低电解锰渣污染风险,实现安全处置具有一定的指导作用。

某尾矿强磁选预富集产品的工艺矿物学研究及可选性分析

西南某多金属原生矿现场尾矿TFe品位13.88%,有害元素S含量为1.24%,主要脉石成分SiO2含量为40.82%,铁矿物主要以赤褐铁矿、菱铁矿及磁铁矿的形式存在,属复杂难选铁尾矿资源。为制定合理的二次资源综合回收工艺,从工艺矿物学角度出发,利用场发射扫描电镜(FESEM)、背散射电子成像(BSE)、X射线能谱分析(EDS)、矿物特征自动定量分析系统(AMICS)等多种检测手段,对现场强磁选预富集产品开展了矿物组成、铁矿物粒度分布、主要元素赋存状态、嵌布特征、解离特征以及热分解特性等系统的工艺矿物学研究。结果表明:采用预氧化—低温还原磁化焙烧—弱磁选选冶联合工艺,预富集产品经550℃预氧化7.5min后,在450℃、还原势R=0.6的条件下磁化焙烧7.5min,可获得作业产率90.84%、铁品位30.02%、磁化率95.05%的磁化焙烧产品;磁化焙烧产品再磨至-38μm占89.5%,经两段弱磁选铁,可获得作业产率28.94%、铁品位60.18%、铁作业回收率63.86%的铁精矿。研究结果可为后续开展合理的资源高效、综合回收试验提供理论支撑。

焙烧温度对硫酸活化稀土尾矿成形催化剂脱硝性能的影响研究

以硫酸活化稀土尾矿催化剂粉末为原料,通过添加助剂和整体挤压的方式制备成形催化剂,对其进行XRD、BET、XPS、H_(2)-TPR表征分析,并在脱硝活性实验平台上测试催化脱硝反应活性和N_(2)选择性,确定了合适的催化剂焙烧制度。结果表明,350℃焙烧的条状催化剂具有最优催化脱硝活性和最大比表面积,其Fe2p轨道的XPS谱峰向高结合能方向偏移,Fe-Ce协同作用明显。以此焙烧温度可以制备出脱硝效率为81%且N_(2)选择性高的蜂窝状催化剂,其机械强度满足成形催化剂的国家标准。

浅析咖啡烘焙回温点对咖啡品质稳定性的影响

随着生活水平的不断提升,咖啡越来越受到消费者的欢迎。因此,确保咖啡在烘焙中具备稳定的品质至关重要。基于此,本研究通过大量对比试验,深入研究咖啡烘焙工艺关键步骤,对比多次烘焙过程中各个关键温度点的实验数据得出结论:保证烘焙过程中的回温点稳定,有助于提高烘焙咖啡的稳定性。

熔融钒渣析晶调控高效提钒机理

基于熔融钒渣在不同冷却制度下导致钠化焙烧-水浸工艺提钒率波动大的问题,本文采用光学显微镜(OM)、X射线衍射(XRD)、扫描电镜(SEM+EDS)及电子探针(EPMA)等表征方法,研究熔融钒渣中钒的析出及钒尖晶石结晶特征对钒提取率的影响,并深入探讨了析晶调控高效提钒机理。结果表明:熔融钒渣的水淬温度对熔融钒渣中钒的析出率、钒尖晶石结晶粒度及钒渣钠化焙烧-水浸过程钒物相转化率及浸出率影响显著。在熔融钒渣降温过程中,1400~900℃为尖晶石快速成核生长期,900℃水淬后,钒基本完成从液相向尖晶石固相中的迁移,结晶相以钒铁尖晶石为主,其中钒呈均匀分散状态;900℃后,尖晶石生长变缓,并以钛铁尖晶石沿钒尖晶石边缘析出为主,尖晶石内部仍呈现钒的“中心聚集效应”。对1400℃、900℃和400℃水淬钒渣(Water-quenched vanadium slag,WQVS)分别进行钠化焙烧-水浸试验,水淬钒渣粒度小于0.15 mm,m(Na_(2)CO_(3))∶m(NaCl)∶m(WQVS)=10∶3∶100,焙烧温度为780℃,焙烧时间为200 min。将焙烧产物磨细至粒度小于0.18 mm后80℃水浸,浸出时间为45 min,钒浸出率分别为75.15%、95.09%和78.78%。这表明将熔融钒渣缓冷至900℃水淬可有效提高钠化焙烧-水浸工艺的钒提取率,并同时提高生产效率。