| China is a traditional agricultural country and the largest consumer of potash fertilizer.The efficient enrichment of potash(KCl)from potassium mineral,which is the main raw material for potash fertilizer production with a commonly employed method like froth flotation,cannot only promote the production increase of potash fertilizer,but also relieve the question of food shortage caused by population growth.In this study,two series of novel Gemini surfactants,which own double hydrophilic/hydrophobic groups,were synthesized in our lab and introduced as collectors in flotation of potassium ore firstly.The hyamine-based Gemini surfactants were compared with the monomer collector 1-octadecylamine(ODA)in froth flotation of sylvine ore,while the morpholine-based Gemini surfactants were contrasted to the monomer collector dodecylmorpholine(DMP)in reverse froth flotation of carnallite ore.Finally,the mechanism of the novel Gemini collectors with stronger collecting performance was discussed and the flotation behaviors of minerals were explained.The mixture of N,N-dimethylalkyl-1-amine with different carbon chain length and 1,4-dibromo-butan was heated and the productions of BAB-series surfactants were synthesized from it.On the other hand,the mixture of 1-bromoalkane with different carbon chain length and morpholine was heated and the production was mixed,heated and reacted with 1,4-dibromo-butan.The final productions were MBAB-series surfactants.The BAB and MBAB series surfactants were characterized by Fourier transform infrared(FTIR)spectrum,mass spectrometry and Nuclear magnetic resonance(NMR)spectrum analysis.The collecting ability of BAB collectors for KCl and MBAB collectors for Na Cl were compared with Octadecylamine(ODA)and Dodecylmorpholine(DMP)by micro-flotation tests,respectively.At the room temperature(25?),the Gemini collectors had stronger collecting ability and excellent selectivity than monomer.Even if the temperature of pulp was as low as 0?,Gemini collectors still show stronger low temperature resistance than monomer collectors.The KCl recovery with 8×10-6 mol/L BAB-18 and ODA were 99%and 28%,respectively.And the Na Cl recovery obtained from 5×10-4 mol/L MBAB-16 and DMP were 97%and 31%,respectively.Whether it was the novel Gemini collectors or the corresponding monomer collector,the collecting effect in acidic pulp environment is better than that in alkaline environment.Further,the performance of the BAB-series collectors was less affected by the content of Mg Cl2 in the flotation water,which exhibited a more stable application effect than ODA.Through bench-scale flotation tests,Gemini collectors maintain excellent flotation performance at room temperature or low temperature,while monomer collectors lose part of their collecting capacity and selectivity at low temperatures.The mechanism of the excellent flotation performance of Gemini collectors were studied by FTIR spectrum,contact angle tests,surface tension tests,turbidity tests and Krafft point comparison tests.The results of FTIR spectrum and contact angle tests showed that Gemini collectors was easily adsorbed on the surface of target minerals but there was hardly adsorption on the surface of non-target minerals,so Gemini collectors could significantly improve the hydrophobicity of the target minerals without affecting the non-target minerals.Meanwhile,the ability of Gemini collectors to improve the floatability of minerals is significantly better than that of monomer collectors.The results of surface tension,turbidity tests and Krafft point comparison tests showed that the critical micelle concentration(CMC value),critical dissolved concentration and Krafft point of Gemini collectors are all lower than those of monomer collectors.Thus,Gemini collectors have better solubility,dispersion and better collecting ability at normal or low temperature.Finally,an adsorption model was established to explain the mechanism by which Gemini collectors can promote the enrichment behavior of potassium salt minerals.Finally,an adsorption model was established to explain the flotation behavior of the Gemini collector for potassium minerals. |
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