The effect of molecular weight on the adsorption and efficacy of polysaccharide depressants

Long chain polysaccharide polymers, such as carboxymethyl cellulose (CMC) and guar gum, are commonly used in flotation to depress gangue minerals. These depressants are in widespread use in the flotation of platinum group minerals contained in the Merensky ore body where the dominant gangue minerals are talc, pyroxene and feldspar. The molecular weight and degree of substitution of these polysaccharides are known to be significant factors influencing the behaviour of such depressants. In the present study CMC and guar at different dosages and with different average molecular weights were used to investigate their effectiveness in depressing gangue minerals. The high molecular weight depressants ranged between 600,000 and 700,000 g/mol and the low molecular weights, 40,000-70,000 g/mol. The depressants were tested using microflotation, batch flotation and equilibrium adsorption studies. The investigation showed that, at starvation dosages (100 g/t) during batch flotation, the high molecular weight polymers did not depress naturally floating gangue (NFG), whereas the low molecular weight depressants did. At higher dosages (300 g/t), both high and low molecular weight polymers depressed all NFG, without depressing sulfide recovery in the pulp. The high molecular weight polymers were significant froth destabilisers, which suggested that they were acting as good slime cleaners. This, combined with their ineffective depression of NFG at low dosages, suggested that the high molecular weight polymers were selectively adsorbing to hydrophilic gangue (pyroxene and feldspar). Adsorption isotherm experiments gave the maximum adsorption densities attainable at equilibrium. These were compared to the adsorption densities of the polymers in the microflotation and batch flotation experiments. This information showed that very little polymer was required to destabilise bubble-particle interaction during microflotation tests. At conventional plant depressant dosages of 100-300 g/t, adsorption densities range from ∼20% to 50% of maximum.     

铜锌铁多金属矿石分选

研究了复杂难选镁质矽卡岩型铜锌铁多金属矿石的分选。所研究矿石组成和结构复杂，含铜、锌、铁等３０余种金属矿物。各种金属矿物嵌市粒度不均匀，密切共生，相互嵌镶，加上难浮墨铜矿和易氧化、具有磁性的磁黄铁矿的存在，导致分选的困难和流程结构的复杂。采用优先浮选－浮尾磁选－磁选精矿再磨后浮选脱硫－脱硫后铁精矿再磁选精选流程，以及使用合理的浮选药剂制度，能获得合格的铜、锌、铁精矿和好的分选指标。墨铜矿用硫酸法回收。     

羧甲基纤维素在铌矿物选别中抑制行为的研究

讨论了弱磁尾矿中的铌矿物浮选产物中羧甲基纤雏素对各种脉石矿物的抑制行为，建立了铌矿物选别的脉石抑制剂——羧甲基纤维素的吸附模型。     

降凝剂BEM降低原油凝点的机理探讨

研究了从大原油和冀东原油分离出的蜡（含2％相应的胶质）用降凝剂BEM处理后X射线衍射图的变化和几种原油以降凝剂BEM处理后蜡晶尺寸的变化及加剂原油经析蜡高峰区的泵剪切后蜡晶尺寸的变化,X射线衍射数据证实降凝剂通过共晶作用改变蜡晶的结构,蜡晶尺寸的变化说明,降凝剂使原油的蜡晶变大,进而降低原油的凝点,剪切破坏蜡晶的结构是剪切引起原油凝点上升的主要原因。     

Selective depression action of taurine in flotation separation of specularite and chlorite

Chlorite, as the most representative gangue mineral associated with specularite, of which the separation of these two minerals is difficult. This paper investigated the depression effect of taurine on specularite/chlorite separation via flotation experiments, adsorption tests, contact angle measurements, Zeta potential detection, FT-IR measurements, and XPS analyses. The results of single mineral flotation indicated that chlorite could be depressed selectively by taurine with the recovery of less than 30%, but the floatability of specularite remains high with recovery rate of 81.77% at pH 10. The artificial mixed mineral flotation results confirmed the effectiveness of taurine as a depressant. Surface adsorption, contact angle, and Zeta potential detection revealed taurine primarily adsorbs on the chlorite surface, which hampered the DDA’s subsequent adsorption and results in the chlorite’s poor floatability. The FT-IR spectra and XPS analyses provided further proof that taurine adsorbed on chlorite surface as an electron donor, and part of the electrons transferred from the sulfonic acid group of taurine to metal ions during the adsorption process. In addition, the hydrogen bond between amino-group of taurine and O ions in chlorite surface was also formed in the adsorption process. Finally, optimized adsorption configurations of taurine on chlorite surfaces were proposed.     

A STUDY ON ESTERIFIED COPOLYMER OF MALEIC ANHYDRIDE AND VINYL ACETATE AS POUR-POINT DEPRESSANT FOR DIESELS

The synthesis and using conditions of esterified copolymer of maleic anhydride and vinyl acetate (ESMVA) as pour-point depressant for diesel fuels were investigated. ESMVA was produced by using Maleic a hydride, vinyl acetate and 1-tetradecyl alcohol as raw materials, benzene and toluene as solvents, azobisisobutyronitrile (AIBN) as initiator, p-toluene sulfuric-acid as catalyst, at 138°C, for 6h. It was used in 10 diesel samples. PP(Pour-Point) of 0^# diesel from Jinzhou Refinery was lowered by 14∼23°Cand CFPP(Cold Filter Plugging Point) 2∼4°C, PP of 0^# diesel from Yanshan Refinery 16∼30°C and CFPP 2°C. Depression mechanism of ESMVA was discussed.     

论复合抑制剂在优先浮选菱锰矿碳酸盐矿石中的作用

采用复合抑制剂取代传统药剂水玻璃，可以改善菱锰矿浮选效果。在用油酸钠优先浮选菱锰矿碳酸盐矿石的选矿中，复合抑制剂的作用主要表现为：ａ．调整捕收剂溶液的泡沫结构；ｂ．改善捕收剂附着矿粒的选择性；ｃ．防止了细粒存在时所得到的过稳定泡沫“跑槽”。     

铜抑制剂巯基乙酸的合成工艺

巯基乙酸是硫化铜矿物的抑制剂,广泛用于铜钼浮选分离。本文对巯基乙酸的合成工艺进行了比较研究,认为硫氢化钠法和硫代硫酸钠法生产成本低,适宜于选矿用巯基乙酸的生产,而硫脲法可得到较高浓度的巯基乙酸。     

丙烯酸酯-苯乙烯二元共聚物的合成及其降凝性能

为改善柴油的低温流动性能,以丙烯酸、高碳醇、苯乙烯等为主要原料,采用了酯化和溶液聚合法在实验室里合成丙烯酸酯-苯乙烯二元共聚物作为降凝剂。考察了在聚合过程中单体配比、引发剂用量以及共聚物单独使用时和复配使用对抚顺石油二厂0 # 柴油的降凝效果。实验结果表明丙烯酸十六醇酯-苯乙烯二元共聚物与丙烯酸十八醇酯-苯乙烯二元共聚物以2∶1(质量比)进行复配,降凝剂质量分数为0 .5 %时,能将0 # 柴油凝点降低2 3℃。     

The depression behavior and mechanism of tragacanth gum on chalcopyrite during Cu-Mo flotation separation

In this work, tragacanth gum (TG), a nontoxic and environmental friendly organic polymer, was used to replace the traditional inorganic depressants of chalcopyrite during the flotation separation of copper-molybdenum sulfides. The single mineral flotation and artificial mixed minerals flotation experiments were conducted to investigate the effect of TG on flotation separation behaviour of molybdenite and chalcopyrite. The TG’s adsorption mechanism on molybdenite and chalcopyrite was investigated by X-ray photoelectron spectroscopy (XPS) and Time-of-flight secondary ion mass spectrometry (ToF-SIMS). The flotation experiment results showed that at pH 3–8, TG had a significant selective depressive effect on chalcopyrite flotation and it was enhanced with increasing TG concentration, but hardly affected the molybdenite flotation. XPS analysis showed that TG was chemically adsorbed on both molybdenite and chalcopyrite surfaces and ToF-SIMS results demonstrated that the interaction of TG and chalcopyrite was stronger than that of TG and molybdenite. Further, XPS narrow scanning analysis suggested that TG might chemisorb onto chalcopyrite via chemical bond between the carboxyl groups and Fe sites on bulk chalcopyrite surface as well as the hydrogen bond between the hydroxyl groups and surface Fe oxides/hydroxides. The strong TG adsorption on chalcopyrite hindered the subsequent adsorption of PBX on chalcopyrite surface, thus chalcopyrite was significantly depressed and Cu-Mo flotation separation was achieved.