药剂预处理金精矿氰化工艺研究与实践

对河台金矿金精矿氰化工艺,通过采用药剂X预处理的方法,提高了氰化浸出速度,优化了相关作业条件,增加了氰化处理能力。同时该法使用后,降低了材料消耗与处理成本,提高企业经济效益。     

强化精选作业提高铜精矿品位

针对湖北某铜矿精矿品位偏低的实际生产情况,在查阅资料和选矿试验的基础上,提出合理的选矿工艺改进措施,经过多次的技术改造,铜精矿品位提高了2．54％,同时回收率也提高了1．03％。     

某铜铁矿选矿厂铁精矿降硫试验研究

通过对含硫铁精矿的试验研究分析结果表明,直接用该厂现有的工艺流程对铁精矿进行降硫是不可能达到所要求的质量标准的,其主要是受到磁黄铁矿的影响,本文详细分析了该铁精矿难降硫的原因,并且认为要想获得合格产品,选矿厂必须对现有工艺流程进行改造。     

焙烧钼精矿块新生产线压制工艺参数优化与研究

焙烧钼精矿块的生产较钼铁具有辅料消耗少、节能、环保以及生产成本低的独特优势，随着焙烧钼精矿块炼钢技术的日趋完善和进步，国内使用钼铁炼钢将随之减少，利用焙烧钼精矿块用于炼钢其前景广阔。本文通过焙烧钼精矿块新生产线对添加剂浓度／用量、干燥时间、物料粒度选择等不同参数试验，从而确定了焙烧钼精矿块新生产线压制最佳工艺参数，同时提高了焙烧钼精矿块成球率和产品质量，深受国内外用户青睐，经济效益明显。     

Antibacterial activity of cranberry juice concentrate on freshness and sensory quality of ready to eat (RTE) foods

Ready-to-eat (RTE) foods are not further treated before consumption in such a way that may significantly reduce the microbial load, therefore the risk of foodborne disease must be considered. In this regard, the use of natural antimicrobial compounds is an interesting method to be considered. On this topic, the antibacterial activity of cranberry juice concentrate (CJC) have been evaluated in vitro and in situ against 3 foodborne pathogenic bacteria. Results showed a high antimicrobial effect with a noticeable inhibition capacity against Escherichia coli O157:H7, Listeria monocytogenes, Salmonella typhimurium. Acid sensitivity studies of bacteria indicated that at the same pH level (pH = 2.4) in presence of organic acid solution (citric and quinic acids), cranberry juice concentrate showed greater antibacterial effects than the acids due to their phenolic compounds. In situ studies showed 2.5, 1.8 and 5 log reduction of E. coli, L. monocytogenes and S. typhimurium, respectively in presence of cranberry juice concentrate, on pre-cut red peppers after 7 days of storage at 4 °C. A total inhibition of L. monocytogenes on fresh cranberry fruits in primary day of storage, was observed. Cranberries treated with CJC also showed a 3 log reduction of S. typhimurium after 4 days of storage at 4 °C. The results suggest that CJC can be an effective preservation, source of natural antibacterial, to protect the RTE foods from foodborne pathogens contamination without effecting on sensorial properties of treated samples and allow to maintain the freshness, sensory and the nutritional quality of RTE foods.     

The effect of limited proteolysis by different proteases on the formation of whey protein fibrils

Four proteases: trypsin, protease A, pepsin, and protease M were selected to modify whey protein concentrate (WPC) at a low degree of hydrolysis (0.1, 0.2, and 0.3%) before adjusting to pH 2.0 and heating at 90°C to gain insight into the influence of proteolysis on fibril formation. The kinetics of fibril formation were performed on native and modified WPC using the fluorescent dye thioflavin T in conjunction with transmission electron microscopy and far-UV circular dichroism spectroscopy for the morphological and secondary structural analyses. The change in surface hydrophobicity and content of free sulfhydryl groups were also observed during the formation of fibrils for the native and modified WPC. The content of aggregation and thioflavin T kinetic data indicated that the ability of fibril formation was apparently different for WPC modified by the 4 proteases. Whey protein concentrate modified by trypsin aggregated more during heating and the fibril formation rate was faster than that of the native WPC. Whey protein concentrate modified by the other proteases showed slower aggregation with worse amyloid fibril morphology. Compared with the native WPC, the structure of WPC changed differently after being modified by proteases. The state of α-helix structure for modified WPC played the most important role in the formation of fibrils. Under the mild conditions used in this work, the α-helix structure of WPC modified by trypsin caused little destruction and resulted in fibrils with good morphology; the content of α-helices for WPC modified by other proteases decreased to 36.19 to 50.94%; thus, fibril formation was inhibited. In addition, it was beneficial for the modified WPC to form fibrils such that the surface hydrophobicity increased and the content of free sulfhydryl groups slightly decreased during heating.     

Determination of the effect of dairy powders on adherence of Streptococcus sobrinus and Streptococcus salivarius to hydroxylapatite and growth of these bacteria

Dental caries is a highly prevalent disease caused by colonisation of tooth surfaces by cariogenic bacteria, such as Streptococcus sobrinus and Streptococcus salivarius. Reducing initial adherence of such bacteria to teeth may delay onset of caries. Many foods, such as milk, can inhibit microbial adherence. In this investigation, the effect of untreated (UT) and enzyme-treated (ET) dairy powders on adherence of S. sobrinus and S. salivarius to hydroxylapatite (HA), an analogue of tooth enamel, was examined. Untreated (UT) acid whey protein concentrate (AWPC) 80 inhibited streptococcal adherence to phosphate-buffered saline-coated HA (PBS-HA) and saliva-coated HA (S-HA) by >80% at ?31.25 μg mL⁻¹. UT sweet WPC80, buttermilk powder and cream powder also significantly reduced adherence (P < 0.05). Enzyme-treatment of all dairy powders reduced their anti-adhesion activity. However, ET sweet WPC80 significantly inhibited growth of these streptococci (P < 0.05) at ?0.6 mg mL⁻¹. Therefore, dairy powders may reduce progression of dental caries by their anti-adhesion and/or antibacterial activity.     

显微观测技术在漂粉精生产中的应用

显微观测技术可以有效地监测漂粉精生产的氯化反应进程，准确确定反应终点，从而获得较高的产率和产品质量，显微观测技术还可以用于石料活性的鉴定，简单，准确。     

硫精矿浆高浓度长距离输送试验研究

硫精矿浆高浓度长距离管道输送在国内没有先例。针对这一技术难题,开展了小型矿浆试验,测定了试样的pH值、比重、粒径分布,开展了不同pH值下多种重量浓度的流变特性试验、沉降测试、滑动角和堆积角测试。试验结果表明：矿浆试样浓度为70%和颗粒小于325目时,可以实现硫精矿浆的高浓度长距离管道输送。     

钛精矿的流态化高温碳化低温氯化生产四氯化钛

以钛精矿、碳和Cl2为原料,采用流态化的生产技术,通过气流加热碳使碳的比表面积大于20m2/g,把非多孔型无烟煤在流化床中与空气在500～600℃的高温下进行处理,直到形成多孔状,以380～400℃的低温的条件下,同样用流化床将钛精矿与碳进行100:30的混料后与氯气反应,能够实现四氯化钛(TiCl4)的制备。该方法解决了原料中CaO和MgO在床层中大量积累,并导致沟流出现,破坏流化状态,既避免沸腾氯化对原料的苛刻的要求,也解决了H2SO4法生产的废液环保问题。为解决攀枝花高钙、镁的钛资源利用提供了一个可行的途径。