碳酰胺助浸风化壳淋积型稀土矿工艺研究

研究了以碳酰胺为助浸剂的风化壳淋积型稀土矿浸取稀土工艺。通过柱浸方式模拟原地浸出过程,在单因素试验基础上,采用响应曲面法建立二次多项数学模型,以稀土浸取率为响应值,探究助浸剂碳酰胺浓度、浸取温度和浸取剂溶液pH对稀土浸取率的影响,分析各因素间的交互作用。结果表明,影响稀土浸取率从强到弱的因素依次是浸取剂溶液pH、碳酰胺浓度、浸取温度。在浸取剂乙酸铵浓度0.10 mol/L条件下,最佳工艺参数为碳酰胺浓度0.59 mol/L、浸取温度25.03 ℃、浸取剂pH=5.51,该条件下稀土浸取率响应值为97.50%。实际试验稀土浸取率为96.36%。两者误差较小,表明采用响应曲面模型得到的工艺参数是基本可靠的。     

风化壳淋积型稀土矿闭矿场铵盐淋出液化学沉淀脱氮

铵盐浸取风化壳淋积型稀土矿后残留大量铵盐,对稀土矿闭矿场淋出液进行脱氮处理是解决氨氮污染的有效手段。采用化学沉淀法脱除稀土矿闭矿场淋出液中氨氮,研究了沉淀条件对氨氮去除率的影响,利用响应面法优化沉淀工艺参数,通过溶液化学计算、XRD与SEM等分析化学沉淀脱氮过程及机理。结果表明：在pH=7.0、n(N)/n(P)=1.0/1.1、25℃、反应时间240 s的条件下,氨氮去除率可达86.87%;响应曲面拟合结果表明,各因素对氨氮去除率的影响次序为：NaOH的用量(pH)>n(N)/n(P)>反应时间,优化条件下氨氮去除率高达98.02%,化学沉淀后淋出液氨氮浓度<15 mg/L,达到国家排放标准;沉淀产物主要为MgNH₄PO₄·6H₂O及少量MgHPO₄·3H₂O、Mg(OH)₂和Mg₃(PO₄)₂固体,呈表面粗糙的空心棒状结构。     

聚乙二醇对风化壳淋积型稀土矿浸出的影响

针对氯化铵作为浸取剂浸取风化壳淋积型稀土时,稀土浸取速率较低和浸出周期长等问题,使用聚乙二醇(PEG)为添加剂,通过柱浸试验模拟工业生产中的原地浸出工艺,探究不同聚合度的聚乙二醇对稀土矿渗透性和稀土浸出的影响。结果表明,聚乙二醇400、聚乙二醇1000和聚乙二醇4000溶液在稀土浸出过程中表现出较好的渗透效果。采用质量分数2.00%的聚乙二醇400、聚乙二醇1000、聚乙二醇4000分别与0.20mol/L的氯化铵复配,复配浸取剂溶液在稀土矿样中的渗透速率随着水力梯度的增大呈线性增大,符合达西定律。PEG400+NH_4Cl、PEG1000+NH_4Cl、PEG4000+NH_4Cl以及NH_4Cl溶液的稀土浸出率分别为82.61%、89.12%、70.67%和88.06%,且当聚乙二醇1000作为助浸剂时,渗流速率最大,渗透效果最佳。添加了聚乙二醇1000的复配浸取剂溶液,在浸取风化壳淋积型稀土矿中稀土的反应过程符合内扩散动力学模型。研究结果对提升复配浸取剂溶液在稀土矿体中的渗流速率有重要意义。     

风化壳淋积型稀土矿矿石性质及稀土在各粒级上的分布

研究了风化壳淋积型稀土矿矿石性质及稀土在各粒级上的含量。采用热重分析、EDTA容量法、紫外分光光度法、原子吸收分光光度法、甲醛容量法等测试手段,对矿石的多水性、吸附稀土离子的稳定性、原矿的缓冲性、吸附离子的可交换性这四大物理化学性质进行了验证,对稀土在各粒级上的含量进行了测定,为进一步合理利用该矿石资源提供理论指导。     

复合铵盐浸出风化壳淋积型稀土矿的研究

采用复合铵盐作浸出剂浸出风化壳淋积型稀土矿中的稀土。考察浸出剂的配比、浓度、液固比、流速、pH等因素对稀土浸出率的影响。结果表明,NH4Cl、NH4NO3、(NH4)2SO4质量比为4∶5∶6的复合铵盐浸出剂为最佳组合;液固比越大、流速越慢,浸出率越高;当浸出剂浓度为10g/L、pH=3.5时浸出效果最好。     

广西某银矿选矿流程精益化管理研究

矿山选矿阶段作为矿石的主要加工处理过程,是影响矿石精矿品位和矿山经济效益的重要因素,选矿流程管理不当会造成矿石精矿品位降低和矿山经济效益的流失。通过分析广西某银矿山选矿流程现状,运用鱼刺图分析法列举该流程面临的主要问题,并进一步利用解释结构模型ISM（Interpretive Structure Modeling）流程分析法找出瓶颈影响因素。模型分析结果表明,该银矿选矿流程存在的最主要问题是精益理念不强、现场管理不当和原矿石品位低,并针对模型分析结论提出该银矿选矿流程精益化管理建议。     

新型浮选药剂B130浮选铜绿山难选氧化铜矿石试验研究

本文研究了新型选矿药剂B130浮选大冶铜绿山氧化铜矿。小型试验,工业试验和工业试验结果表明,B130不但能较大幅度提高氧化铜矿浮选指标,且还有利于金、银的回收。     

Investigations on the Collector Reagent Development for the Recovery of Cassiterite from the Gravity Tails of a Low Grade Indian Tin Ore

Abstract

Results of the experimental studies carried out for developing a flowsheet for the recovery of cassiterite from the gravity tails of a low grade lode type tin ore (Tosham, Haryana) from India by froth flotation using three different collector reagents — alkyl phosphonic acid, sodium sulfosuccinamate and alkyl phosphoric acid ester are presented. The studies include micro-flotation of high purity cassiterite from Tosham, bench scale studies on gravity tails of Tosham tin ore, large scale semi-continuous test with relatively better reagent at optimised flotation conditions ending up with development of conceptual flowsheet meant for obtaining fuming grade cassiterite concentrate. The performance of various collector reagents was analysed on the basis of conventional metallurgical accounting methods and flotation kinetic rate constants. From a feed containing 0.24% Sn, a float product analysing 7% Sn with 55% recovery was obtained using a reagent combination of alkyl phosphoric acid ester-sodium silicofluoride - commercial grade sulfuric acid and citric acid.     

Luminol-Based Enhanced Chemiluminescence Assay for Quantification of Peroxidase and Hydrogen Peroxide in Aqueous Solutions: Effect of Reagent pH and Ionic Strength

The effect of reagent pH and ionic strength was evaluated on the horseradish peroxidase (HRP)-luminol-p-iodophenol enhanced chemiluminescence assay. This assay was optimized for HRP and H2O2 quantification during enzyme-mediated remediation of groundwater or wastewater contaminated with phenolic chemicals. The maximum chemiluminescence intensity (ICLmax) and total area under the chemiluminescence intensity profiles were measured as a function of p-iodophenol concentration, reagent solution pH, and reagent ionic strength. ICLmax values were optimum at pH 8.5 and increased linearly with reagent ionic strength. Optimum chemiluminescence enhancement was produced at a p-iodophenol concentration of 0.3 mM under the reaction conditions. ICLmax values were linearly correlated with HRP and H2O2 concentrations within the ranges of 0.1–1 activity units/mL and 0.1–1 mM, respectively. Results indicate that the HRP-luminol-p-iodohenol enhanced chemiluminescence assay has a potential to be used for quantification of HRP activity and H2O2 concentration in aqueous solutions encountered in groundwater remediation or wastewater treatment scenarios.     

Effects of Calcium and Chloride Ions in Iron Ore Reverse Cationic Flotation: Fundamental Studies

ABSTRACT

In this work, the simultaneous effects of Ca²⁺ and Cl^? ions in an aqueous solution at pH 10.5 on the flotation of quartz (the main impurity in itabiritic iron ore) and hematite by starch and amine was investigated. A strong depression in the flotation of both quartz and hematite conditioned with CaCl₂ was observed. This effect was higher for hematite than for quartz. Based on zeta potential measurements and the speciation diagram of calcium in aqueous solutions, the physical adsorption of Ca²⁺ on the surfaces of both minerals was inferred. The infrared spectrum of quartz conditioned with CaCl₂ at pH 10.5 was similar to its reagent-free reference spectrum. However, a new band at the wavenumber of 1465 cm^?1 was identified in the spectrum of hematite conditioned with CaCl₂; this band did not exist in its reference spectrum. This new band may indicate the chemical adsorption of Cl^? ions on the hematite surface. The complexation of Ca²⁺ by ethylenediaminetetraacetic acid enabled complete quartz recovery with amine. For hematite, recovery was partially restored, probably because of the positive chloro-complexes on the hydrated iron surfaces of hematite, which prevented the adsorption of aminium ions at these sites. Therefore, the selective inverse cationic flotation of itabiritic iron ore at pH 10.5 in water containing Ca²⁺ is possibly only after complexing them with EDTA.     

Effects of Low-temperature Pre-oxidation on the Titanomagnetite Ore Structure and Reduction Behaviors in a Fluidized Bed

Metallurgical and Materials Transactions B - With respect to high efficient utilization of low-grade iron ore resource, the behavior of low-temperature “973&nbsp;K to 1123&nbsp;K...     

Enhanced feeling of recognition: Effects of identifying and manipulating test items on recognition memory.

This study showed that, regardless of its actual status, a test item was more likely to be judged as old if, before making an old–new judgment, Ss attempted to (1) identify a test word or a test picture's name (Exps 1 and 2) or (2) to work on a normally presented test word, such as reversing the letter order of the word or constructing a word that rhymed with the test word (Exp 3). Exp 1 replicated the enhanced feeling of recognition effect reported by M. Watkins and Z. F. Peynircio?lu (1990). Exp 2 extended the effect to a cross-modality priming situation. Exp 3 further extended the finding by showing that the effect could occur for reasons having nothing to do with the perception of test items. Finally, Exp 4 showed that increased exposure to test items alone cannot produce the enhanced feeling of recognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Assessing the Environmental Impacts of a Lean Supply System: Case Study of High-Rise Condominium Construction in Korea

Prefabrication and just-in-time (JIT) delivery are important components of a lean supply system. Past research focuses on how much lead time is reduced and how much costs are saved, but few have studied the environmental impacts. While most of those studies on environmental impacts have focused on select life cycle phases or specific building materials and components, the impacts of different construction methods or supply strategies from the construction phase were ignored or simply approximated. This paper presents the results of a case on the environmental impacts of prefabrication and JIT delivery strategy of rebar supply on a high-rise condominium project in Korea.     

Iron Ore Pellet Dustiness Part II: Effects of Firing Route and Abrasion Resistance on Fines and Dust Generation

Iron ore pellets abrade during their production and handling, which lowers product quality and leads to dustiness issues. Pellets were collected from a variety of plants (operating either Straight-Grate (SG) or Grate-Kiln (GK) furnaces) to understand whether furnace type affects fines and dust formation. Results showed that pellets fired in SG furnaces were less abrasion-resistant (3.5 × lower) than pellets fired in GK furnaces. Concurrently, laboratory pellets were prepared using various ores, binders, and firing temperatures. These were tested to understand the relationship between abrasion index and dustiness. AI was observed to range from 1 to 14%. Dustiness, determined via AI and size distributions of abrasion progeny, ranged from 0.2 to 1.6%. For AI greater than 5%, AI can be used to indicate potentially high levels of dust. For AI less than 5%, there was a poor correlation between AI and dustiness. This was explained by the observation that as AI decreased, the abrasion product fineness increased. The results from parts I and II of this investigation suggest that material loss and levels of pellet dustiness may be significantly affected by pellet quality up to a certain point. Poorly fired pellets will be dusty during handling and transportation, while well-fired pellets will generate less – but finer – material as their quality improves. This could lead to little observed changes in dust generation over a wide range of pellet quality. Dust generation at each site would then depend on the quantity of material produced and their extent of handling.     

Enhanced rehabilitation of gait after stroke: a case report of a therapeutic approach using multichannel functional electrical stimulation

The beneficial effects of using multichannel functional electrical stimulation (MFES) for gait rehabilitation in nonambulatory hemiplegic patients have already been shown. The methodology of application and the results presented were pooled for the whole group of participants, which blurs the exact picture of each particular subject and many vital details are not presented. The purpose of this article is to focus on a single subject from the study and to present all the details of the treatment. The presented subject participated six weeks in the study, first three weeks in MFES therapy and second three weeks in conventional therapy. The effects of each therapy were evaluated by the following measures: temporal-distance parameters of gait, ground reaction forces, goniograms in hip knee and ankle, and assessment of the physical status of the patient according to the Fugl-Meyer evaluation scale. An analysis of the measured parameters showed improved performance of the patient during MFES therapy and stagnation or even slight recession during conventional therapy. The patient achieved independent gait during the three weeks of MFES therapy. At 30 months after the beginning of therapy, the patient was still able to ambulate independently without any significant changes in his gait pattern. The accomplishment was mainly attributed to the avoidance of pathological gait pattern development by using MFES assisted gait training and to the high motivation of the patient to walk and exercise during therapy as well as after he was released to go home.     

Selection of a Viable Upgradation Strategy Through Physico-chemical and Mineralogical Approach: A Case Study of Low Grade Barsua Iron Ore Fines

Detailed characterization study is the pioneer step for any mineral beneficiation scheme. A series of mineralogical and peterographic studies coupled with (Brunauer–Emmett–Teller) surface area, (atomic force microscopy), (laser diffraction particle size analyser), FTIR (Fourier transform infrared spectroscopy), contact angle measurement, zeta potential were carried out, and the findings about the mineralogical and physico-chemical nature of the sample have been described. This paper provides a guide on the proper selection of beneficiation route for iron ore with complex mineral assemblage (Hematite–Goethite–Laterite–Quartz–Kaolinite–Gibbsite). The beneficiation method, especially froth flotation process, potential after a thorough characterization is suggested analysed and the successful upgradation by froth flotation route is envisaged. Flotation results indicated that it is possible to achieve high grade iron concentrate along with lower silica, and alumina content providing a specific reagent regime/system for specific mineral assemblages.     

Effects of Brazelton demonstrations on later parenting: a meta-analysis

Meta-analysis of parenting interventions based on the Neonatal Behavioral Assessment Scale (NBAS) was conducted. Only published studies (n = 13) were included in this analysis, with one effect size entered for each study. The studies contained a total of 668 families, an average of about 51 per study. Effect sizes are reported in terms of the correlation coefficient (r) as well as the difference between experimental and control group means divided by the pooled standard deviation (Cohen's d). Analyses were conducted by weighting each study equally (unit weighting) and also by sample size. Similar average effect size were obtained for both weighting procedures (r's of about.2, d's of about.4), indicating that Brazelton-based interventions during the neonatal period have a small-moderate beneficial effect on the quality of later parenting. The probability of obtaining these findings by chance approached zero. The potential factors influencing these results are discussed, as well as directions for future research.