磷矿物化参数对脲硫酸分解磷矿转化率的影响研究

测定了3种不同磷矿的比表面积、二氧化碳系数、反应活性指数以及抗阻缓系数,通过对比找到磷矿物化参数对脲硫酸分解磷矿转化率的影响规律:比表面积、二氧化碳系数近乎相当时,同一条件下脲硫酸分解磷矿的转化率与反应活性指数呈较大程度的相关性,抗阻缓系数影响不大;比表面积和二氧化碳系数对磷矿转化率的影响程度远小于反应活性指数和抗阻缓系数的影响程度。所得结论为不同磷矿对脲硫酸复肥工艺的适应性评价提供了依据。     

脲硫酸分解磷矿过程第一阶段反应动力学研究

在反应温度333—358 K,硫酸质量分数29%—43%范围内,用纯试剂研究了尿素存在条件下硫酸分解磷矿过程第一阶段的反应速率,得到第一阶段反应活化能为9985 J/mol,反应级数为1.0309;与硫酸分解磷矿反应系统进行对照,对硫酸分解磷矿反应系统,反应活化能为9867 J/mol,反应级数为0.8218。影响反应速率的指前因子为k0,硫酸分解磷矿的k0值相当于脲硫酸分解磷矿的k0值的3.4倍。加入尿素后,第一阶段分解速率明显减慢。该研究较好地解释了脲硫酸分解磷矿工艺过程中磷矿分解率较高,硫酸钙包裹减轻、无需较长的堆置熟化期的问题,对于脲硫酸分解磷矿工艺条件的选择具有理论指导意义。     

在过磷酸钙生产过程添加烷基苯磺酸小试验

近年来各国生产普钙的技术都有不同程度的发展,为了满足消费者的需要,各国都在力图强化普钙的生产过程。众所周知,过磷酸钙生产中硫酸分解磷矿是一典型的局部化学控制反应过程,即在这一过程中有磷矿石的溶解及新的固相—一硫酸钙的形成,两种作用同时进行,其反应速率主要受反应温度及氢离子浓度,穿过表面液膜的扩散以及矿粒有效表面积等因素的影响。磷矿和硫酸进行反应时,Ca~( )离子自磷矿颗粒表面向外扩散,SO_4~-离子向磷矿颗粒扩散,(根据搅拌强度的大小)在离颗粒一定距离处形成一     

微波辐照对低阶煤的表面改性作用

以微波辐照作为低阶煤浮选前的预处理方法,研究微波辐照对低阶煤的表面改性作用。结果表明:微波辐照预处理显著提高了浮选精煤产率与可燃体回收率,在微波处理时间为15min时精煤产率和可燃体回收率达到了最高值,分别为74.56%,84.83%。微波辐照后煤样接触角有所增加,疏水性增强。红外光谱、质量损失与比表面积分析结果表明,存在于煤颗粒小孔中的水分子或者某些极性小分子在微波的作用下被加热去除,从而导致煤颗粒疏水性增强,提高了煤的可浮性。     

硫酸脲分解磷矿反应动力学

通过硫酸脲分解磷矿的搅拌强度和磷矿粒度实验,探讨其中的传递过程。实验研究表明,硫酸脲分解磷矿为典型的缩芯反应,反应过程受产物形成的固膜扩散所控制,在排除液相扩散和反应粒子表面及微孔影响下,进行反应动力学实验。建立了硫酸脲与磷矿反应的动力学模型,由实验数据求得动力学参数,其反应活化能为12．73kJ／mol。     

磷酸分解磷矿化学反应过程研究

为提高用中低品位磷矿制得湿法磷酸的浓度 ,实验用ω(P2 O5)≈ 2 0 %、较洁净的磷酸 ,与云南上蒜磷矿进行分解反应。在实验条件下 ,研究了分解产物Ca(H2 PO4 ) 2 在磷矿颗粒表面形成固体膜的特性 ,以及磷矿粒度、反应时间、反应温度和磷酸初始浓度对磷矿分解率的影响。用扫描电镜观察了磷矿颗粒表面形成的固体膜的形貌特征 ;用粒径不变的缩芯模型来描述磷酸分解磷矿的过程 ;用所测实验数据回归得到了磷酸分解磷矿的经验模型     

磷酸分解磷矿的化学过程及其模型

采用热法磷酸制成含 2 0 % P2 O5左右的磷酸 ,用以与云南上蒜磷矿进行分解反应。在实验条件下 ,研究了分解产物 Ca(H2 PO4) 2 在磷矿颗粒表面形成固体膜的特性。研究了磷矿粒度、反应时间、反应温度、初始磷酸浓度对磷矿分解率的影响。用扫描电镜观察了磷矿颗粒表面形成的固体膜的形貌特征。用粒径不变的缩芯模型来描述磷酸分解磷矿的过程。推导出了该过程的理论模型和实验数据的回归模型     

脲硫酸分解磷矿转化率影响因素的研究

对脲硫酸分解磷矿转化率的影响因素进行了研究,考察了脲硫酸分解磷矿过程中反应时间、反应温度、搅拌速度、矿粉粒度、硫酸用量、酸解剂配比、活化剂用量等对磷矿转化率的影响,获得了脲硫酸分解磷矿的较优工艺条件。在优化的工艺条件下脲硫酸分解磷矿的转化率能够达到94%左右,工艺条件的优化为脲硫酸复肥工艺的工业化实施提供了依据。     

氢氧化镍粉末的化学镀Co-Zn合金表面改性研究

采用化学沉积技术对由水溶液络合沉淀法合成的氢氧化镍粉末进行了表面包覆Co—Zn改性处理,利用扫描电子显微镜分析、比表面积测量、X一射线光电子能谱及原子吸收光谱等对处理前后氢氧化镍粉末的表面形貌、微晶结构、比表面积、元素化学态及镀层组成等进行了表征和研究。结果表明,Co—Zn合金镀层可以均匀包覆在氢氧化镍颗粒表面,氢氧化镍经化学镀处理后其表面微观组织形貌发生了明显变化。化学镀表面改性使氢氧化镍粉末的比表面积有所降低,镀层中的Co、Zn元素均以氧化态形式存在。     

硫酸氢铵分解磷矿动力学研究

在反应温度40—80℃,硫酸氢铵初始浓度3.65—5.22 mol/L,磷矿粒度0.125—0.18 mm,搅拌速度为400 r/m in的条件下,对硫酸氢铵分解磷矿的反应动力学进行了研究,磷矿分解速率随着搅拌速度、反应温度、硝酸浓度和颗粒细度的增加而增加;氢离子通过液膜的扩散传质是该过程的速率控制步骤。应用固体粒径减小的缩芯模型,将上述各影响因素的实验数据回归得到的动力学模型,方差分析表明模型可靠,为硫酸氢铵分解磷矿工艺条件的优化和反应器的设计提供了理论依据。     

活化温度对聚丙烯腈基活性中空炭纤维结构和吸附性能的影响

用质量分数为4%的磷酸氢氨溶液预处理聚丙烯腈(PAN)中空纤维,经预氧化及炭化后,用二氧化碳气体在不同温度下活化40 min,得到PAN基活性中空炭纤维(PAN-ACHF)。考察了活化温度对PAN-ACHF的比表面积、孔径分布、形态和吸附性能的影响。结果表明,随着活化温度的升高,PAN-ACHF表面的孔逐渐加深,且数目逐渐增多,比表面积逐渐增大;当活化温度为900℃时,BET比表面积最大为1 422 m2/g,中孔的比表面积也达到最大,为1 234 m2/g,且孔径主要集中在2~5 nm;PAN-ACHF对肌酐和VB12的吸附率都随着活化温度的升高而增大,当活化温度为900℃时,PAN-ACHF对肌酐和VB12的吸附率都达到最大值.分别为99%和84%。     

Effects of the oxidation temperature on the structure and properties of polyacrylonitrile‐based activated carbon hollow fiber

Polyacrylonitrile (PAN) hollow fibers were pretreated with ammonium dibasic phosphate, oxidized in air, carbonized in nitrogen, and activated with carbon dioxide. The effects of the oxidation temperature of the PAN hollow fiber precursor on the microstructure, specific surface, pore size distribution, and adsorption properties of PAN‐based activated carbon hollow fiber (PAN‐ACHF) were studied. When PAN hollow fibers were oxidized at 270°C, because of drastic oxidation, chain scission occurred, and the number of pores within and on the surface of the resultant PAN‐ACHF increased, but the pores were just in the thinner region of the skin of PAN‐ACHF. The surface area of PAN‐ACHF reached a maximum when the oxidation temperature was 270°C. The adsorption ratios to creatinine were all higher than 90% at all oxidation temperatures, and the adsorption ratio to VB₁₂ reached a maximum (97%) at 230°C. The dominant pore sizes of the mesopores in PAN‐ACHF ranged from 2 to 5 nm. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 203–207, 2005     

A new phosphate pretreatment process for adhesive bonding of magnesium AZ31 sheets

An economic, high efficiency sodium dihydric phosphate surface pretreatment process (SDPT) was developed to improve the adhesive bond performance of 2 mm thick hot-rolled wrought magnesium AZ31 sheets. A phosphating solution with sodium dihydric phosphate (NaH₂PO₄), additive sodium fluoride (NaF), and accelerator sodium molybdate (Na₂MoO₄), sodium tungstate (Na₂WO₄) and potassium nitrate (KNO₃) were developed to pretreat the magnesium alloys. The content of sodium dihydric phosphate in the phosphating solution was strictly controlled to insure it supplied sufficient acid radical HPO₄ ^2? to phosphate magnesium AZ31 alloy. Furthermore, a suitable H⁺ content to keep the pH values in the range of 5–6 for a phosphating solution was necessary. With this SDPT pretreatment process, a coating consisting of the magnesium phosphate, magnesia (MgO), magnesium hydroxide (Mg(OH)₂), magnesium fluoride (MgF₂) and a minor amount of molybdenum oxide(MoO₃) was formed on the surface of the magnesium AZ31. While the SDPT pretreated adhesive-bonded joints had better initial bond strength than phosphate–permanganate process pretreated joints, the corrosion resistance of SDPT pretreated joints was slightly inferior.     

十二烷基硫酸钠对亚麻织物喷墨印花性能的影响

为提高亚麻织物的喷墨印花颜色效果,将十二烷基硫酸钠（SDS）与海藻酸钠（SA）协同作用于亚麻织物的预处理工艺,对处理后织物表面墨滴的铺展面积、喷墨印花色块的颜色参数进行了测试,使用接触角测量仪、扫描电子显微镜（SEM）、固体表面zeta电位仪、X射线光电子能谱仪（XPS）和傅里叶变换红外光谱仪（FTIR）对预处理前后亚麻织物表面物理和化学性能进行了表征。结果表明：与SA预处理织物相比,表面活性剂的引入可使亚麻织物表面墨滴铺展面积减小14%,墨滴渗化程度也明显减小;青色和黑色印花色块的表观颜色深度增加,摩擦色牢度略有降低,断裂强力和耐日晒色牢度无明显改变。同时从SEM图看出,经预处理后,SDS+SA预处理剂在亚麻织物表面上形成了薄膜,纤维间以锯齿状的膜结构堵塞了孔隙,促使更多的活性染料在滴落的位置与纤维发生共价结合;此外,预处理处理后织物的亲水性增加,有利于染料对亚麻纤维的上染。     

常压微波消解-原子吸收光谱法测定磷矿中铅、镉、汞

采用常压微波消解法前处理磷矿样品,使用GGX-9型原子吸收光谱仪测定磷矿中铅、镉、汞含量,铅、镉、汞检出限分别为0.009 3、0.012 0、0.011 0μg/g,加标回收率分别为100.06%～100.18%、99.73%～100.18%、99.51%～100.63%,3种元素的相对标准偏差均在1%左右。     

AZ91D镁合金表面诱导矿化磷灰石层的研究

通过金属螯合剂EDTA在基体表面自组装成膜,在基体表面大量引入活化基团,并利用活化基团诱导磷灰石矿化层的沉积。用GaCl2和溶液和K2HPO4溶液沉淀反应预钙化,在基体表面预沉积出大量的钙磷盐晶核,该钙磷盐晶核可诱导矿化出含有羟基磷灰石相的磷灰石矿化层。实验证明经过自组装、预钙化的基体可在8天内沉积出比较致密、均厚度的磷灰石矿化层。     

Comparison about the structure and properties of PAN‐based activated carbon hollow fibers pretreated with different compounds containing phosphorus

Polyacrylonitrile (PAN) hollow fibers were pretreated with five different compounds containing phosphorus, including ammonium dibasic phosphate, ammonium dihydrogen phosphate, triammonium phosphate, phosphoric acid, and metaphosphoric acid, and then further oxidized in air, carbonized in nitrogen, and activated with carbon dioxide. The effects of different compounds containing phosphorus as pretreating agents on the properties and structure of the resultant oxidized hollow fibers, carbon hollow fibers, and activated carbon hollow fibers are discussed. Comparing the Brunaner‐Emmett‐Teller (BET) surface area of PAN‐activated carbon hollow fibers (ACHF) pretreated with five different compounds, ammonium dibasic phosphate > triammonium phosphate > ammonium dihydrogen phosphate > phosphoric acid > metaphosphoric acid, and the surface area of mesopores in PAN‐ACHF pretreated with ammonium dibasic phosphate reaches maximum, 174 m² g^?1. The adsorption ratio to mesomolecule adsorbate, VB₁₂, of PAN‐ACHF pretreated with ammonium dibasic phosphate also reaches maximum, 97.7 wt %. Moreover, the dominant pore sizes of PAN‐ACHF range from 2 to 5 nm in diameter. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 294–300, 2005     

表面磁种法分选磷矿石的理论与实践

介绍了分选矿石的一种新工艺－表面磁种法。在成功地分选了磷矿石的基础上，从电化学的角度分析了矿粒表面磁罩盖过程的机理。     

Corrosion stability of polyester coatings on steel pretreated with different iron–phosphate coatings

The influence of steel surface pretreatment with different types of iron–phosphate coatings on the corrosion stability and adhesion characteristics of polyester coatings on steel was investigated. The phosphate coating was chemically deposited either from the simple novel plating bath, or with the addition of NaNO₂, as an accelerator in the plating bath. The morphology of phosphate coatings was investigated using atomic force microscopy (AFM). The corrosion stability of polyester coatings on steel pretreated by iron–phosphate coatings was investigated by electrochemical impedance spectroscopy (EIS) in 3% NaCl solution, while “dry” and “wet” adhesion were measured by a direct pull-off standardized procedure. It was shown that greater values of pore resistance, R_p, and smaller values of coating capacitance of polyester coating, C_c, on steel pretreated with iron–phosphate coating were obtained, as compared to polyester coating on steel phosphated with accelerator, and on the bare steel. The surface roughness of phosphate coating deposited on steel from the bath without accelerator is favorable in forming stronger bonds with polyester coating. Namely, the dry and wet adhesion measurements are in accordance with EIS measurements in 3% NaCl solution, i.e. lower adhesion values were obtained for polyester coating on steel phosphated with accelerator and on the bare steel, while the iron–phosphate pretreatment from the novel bath enhanced the adhesion of polyester coating on steel.     

Effects of oxidation time on the structure and properties of polyacrylonitrile‐based activated carbon hollow fiber

Polyacrylonitrile (PAN) hollow fibers were pretreated with ammonium dibasic phosphate, then further oxidized in air, carbonized in nitrogen, and activated with carbon dioxide. The effects of oxidation time of PAN hollow fiber precursor on the microstructure, specific surface, pore size distribution, and adsorption properties of PAN‐based activated carbon hollow fiber (PAN‐ACHF) were studied in this work. Both of specific surface area and adsorption ratio to VB₁₂ reach maximums when PAN hollow fibers are oxidized for 5 h in air. The adsorption ratios for creatinine are all higher than 90% over all oxidation time. After 5 h of oxidation, the number of pores on the surface obviously increases, and the pore size is uniform. After 7 h of oxidation, the number of macropores in PAN‐ACHF increases. The dominant pore sizes of mesopores in PAN‐ACHF range from 2 to 5 nm. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007