Ethyl Thiocarbamate Research Articles

Selectively improves chalcopyrite hydrophobicity to achieve copper and arsenic separation: Interfacial reaction and application research

The efficient separation of chalcopyrite and arsenopyrite is significant for preventing and controlling arsenic pollution. Herein, sodium diisobutyl dithiophosphate (SDD) selectively improves chalcopyrite hydrophobicity to achieve copper and arsenic separation in low alkali. The flotation test results show that SDD is stronger than butyl xanthate and ethyl thiocarbamate regarding selective collection ability. SDD accurately separates chalcopyrite and arsenopyrite under low alkali conditions. Frontier orbit analysis shows that the feedback π and positive σ bonds between SDD and arsenopyrite surface are the weakest among the three collectors. Surface wettability, adsorption capacity, FTIR, XPS, and adsorption simulation calculations reveal more detailed collecting mechanisms. Analysis shows that SDD can selectively improve the hydrophobicity of the chalcopyrite surface. The above results were attributed to SDD breaking the CaOH+ adsorption barrier on the chalcopyrite surface. On the contrary, the interaction between SDD and arsenopyrite is weak, resulting in SDD being unable to break through the cover of CaOH+ on the surface of arsenopyrite.

Utilizing H2O2 for the selective flotation separation of chalcopyrite and galena with their surface pre-adsorbed with Isopropyl Ethyl Thiocarbamate

Chalcopyrite and galena often coexisted in ore deposits, and they are usually processed by bulk flotation and then separated to obtain valuable mixed concentrateds. In this paper, we propose a flotation reagent strategy, that uses Isopropyl Ethyl Thiocarbamate (IPETC) and hydrogen peroxide (H2O2) to achieve different floatability on chalcopyrite and galena, it is evident that chalcopyrite and galena with IPETC adsorbed on the surface can be separated by H2O2. The flotation results show that H2O2 has a great inhibition effect on galena and exhibits a weak inhibition effect on chalcopyrite. Mixture of chalcopyrite and galena with IPETC adsorbed on the surface was successfully separated by flotation with 15 mg·L-1 H2O2 at pH 7. The inhibition mechanism of H2O2 was analyzed by contact angle measurements, single-channel scanning Inductively Coupled Plasma emission spectroscopy (single-channel ICP) analysis, Fourier Transform Infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The characterization analysis indicates that the rate of H2O2 oxidation of galena is faster, resulting in more hydrophilic oxidation products such as oxides and hydroxides on the surface of galena, while the surface of chalcopyrite is less affected by H2O2. Also, compared with chalcopyrite, the adsorbed IPETC on the galena surface can be easily blanketed by oxidation products, so realizes the effective separation of chalcopyrite and galena.

Efficient flotation recovery of lead and zinc from refractory lead-zinc ores under low alkaline conditions

In this study, a new flotation approach, a low-alkaline and non-desliming process, was introduced for improving lead and zinc recoveries, lowering production cost and reducing environmental pollution. Lab-scale experiments results show that the new process contributed to the flotation of the complex mixed sulfide-oxide lead and zinc ore regarding two aspects: (1) High alkaline process (pH = 12±) was replaced by low alkaline process (pH = 9±) by using collector WS (a mixture of ethyl thiocarbamate, ammonium dibutyldithiophosphate and dithiophosphate-25) and combined depressant Na2S/ZnSO4/Na2SO3 for lead sulfide flotation; (2) Non-desliming process was successfully achieved by using collector MA (a mixture of ether amine, hydroxyethyl cellulose and polyacrylic acid) and combined depressant SHP/SS (sodium hexametaphosphate/sodium silicate) for zinc oxide flotation. And 43.37% Pb in the Pb concentrate was recovered, the corresponding Pb grade was 52.73%, total 84.42% Zn was recovered by the flotation of zinc sulfide minerals and zinc oxide minerals. Moreover, the two aspects of the new approach were systematically verified from lab-scale to industrial-scale application. The industrial-scale flotation tests show that Pb recovery in Pb concentrate increased by 1.86% compared with that of original system during industrial-scale tests period, and the Pb recovery increased by 4.09% compared with that of original system before industrial-scale tests period, while the Zn operating recovery in zinc oxide concentrate improved by 19.52%. Moreover, the total reagent cost of the whole new process significantly declined by 3.93 yuan per ton of ore.

Study of solvent effect on the stability of isothiocyanate iberin, a breakdown product of glucoiberin

Iberin (IBR) is an isothiocyanate (ITC) with chemopreventive properties on different types of cancer. The need of quantifying IBR either in natural products or in food supplements makes the availability of suitable and stable analytical standards necessary. The choice of proper solvents for ITCs storage and experiment setup is a critical point due to ITCs reactivity. As IBR reference standard is sometimes supplied in ethanol, methanol is also frequently utilised as a solvent in ITCs analysis. A study on IBR stability in the most common solvents used in liquid chromatography and at different pH is presented.A fast UHPLC-PDA-ESI/MS analysis was used to separate IBR from degradation products, to monitor IBR stability at three temperatures and at different pH. The fastest degradation was observed in methanol/water mixture. IBR degraded always faster in methanol than in ethanol. At 20 °C, the degradation in ethanol and in water was comparable. At 30 °C and 40 °C the degradation in water was faster than either in ethanol or methanol. Ethyl thiocarbamate, methyl thiocarbamate and disubstituted thiourea degradation products, in ethanol, methanol and water respectively, were tentatively assigned. IBR was stable in acetonitrile and at acidic pH but it was unstable at alkaline pH.

Thiocarbamate-Based Synthesis of 2,4,5,6-Tetrahydro-3H-1,2,4-Triazepine-3-Thiones

A five-step synthesis of 5,7-diaryl-substituted 2,4,5,6-tetrahydro-3H-1,2,4-triazepine-3-thiones starting from ethyl thiocarbamate was developed. The synthesis included a three-component condensation of ethyl thiocarbamate with aromatic aldehydes and p-toluenesulfinic acid to give O-ethyl[(aryl)(tosyl)methyl]thiocarbamates which were transformed into the corresponding O-ethyl (3-phenyl-3-oxopropyl) thiocarbamates by treatment with the sodium enolate of dibenzoylmethane followed by base-promoted retro-Claisen condensation. Reaction of the prepared thiocarbamates with hydrazine and subsequent acid-catalysed cyclisation of the derived 4-[(3-hydrazono-3-phenyl)prop-1-yl]semicarbazides gave the target triazepines.

Study on Potential-Controlled Flotation Test of a Copper-Lead-Zinc Polymetallic Sulphide Ore

The study on potential-controlled flotation test of differential flotation process was carried out in the light of the change of a certain ore properties. The test used self-developed EMZ-91, as well as conventional collectors of ethyl thio carbamate and butyl xanthate for the flotation of copper, lead and zinc ores respectively, in which the copper sulfate was used as the activator of zinc mineral. The new differential flotation process, which is using lime to regulate pulp potential, produced the copper concentrate grading 27.18% copper at 73.37% recovery, the lead concentrate grading 66.00% lead at 63.00% recovery, and the zinc concentrate grading 55.27% zinc at 87.69% recovery.

Experimental Research on Rough Flotation of Lead in Bainiuchang Lead-Zinc Mines

Containing Pb (1.09% ) and Zn (1.97%),the lead-zinc sulphide ore of Bainiuchang mine is a refractory resource in Yunnan Mengzi. The flotation performance of lead is ineffective in plant practice. This research is carried out to enhance the rough flotation performance of lead. With the dosage of lime and zinc sulfate as depressors, sodium hexametaphosphate as dispersant, and ethyl thio carbamate and MA as combined collector, the grinding fineness of 85% , a lead concentrate with lead grade of 17.68%, lead recovery rate of 75.59%, and zinc grade of 7.16% was obtained. The performance of rough flotation of lead is improved.

Flotation Desulfurization of High-Sulfur Bauxite with Ethyl Thio Carbamate as Collector

The desulfurization of high-sulfur diasporic bauxite （from China） with flotation process and ethyl thio carbamate as collector was studied, and the effects of flotation time, pulp density, pH value and particle size of ores were examined. The experimental results indicate that the sulfur in bauxite was successfully decreased through flotation. The sulfur content of bauxite was lowed to 0.66% under the condition of pH value 4, the dose of flotation agent ethyl thio carbamate 0.5kg/t, frother 20g/t, flotation time 15 minutes, pulp density 10%, the particle size of ores ≦0.09 mm, and the reclamation of Al2O3 is 90.16% as well. The flotation kinetics of flotation desulfurization was also studied.

Some Nucleophilic Reactions with Isothiocyanatoazobenzene

The reactivity of Isothiocyanatoazobenzene 2 towards some nucleophiles was investigated. Thus, reaction of isothiocyanate 2 with aromatic amines gave thioureas 3a–d . The reaction of compound 3a with arylidenemalononitriles 4a,b afforded the corresponding 1,3-pyrimidines 7a , b . Thiosemicarbazide 8 and ethyl thiocarbamate 9 were synthesized by interaction of isothiocyanate 2 with hydrazine hydrate and ethanol, respectively. Cyclocondensation of isothiocyanate 2 with 2-aminophenol and anthranilic acid produced the novel benzoxazole 11 and quinazolinone 13 derivatives , respectively. Finally, treatment of isothiocyanatoazobenzene 2 with compounds 14 and 17 afforded the novel thioureas 15 and 18 derivatives, respectively. The structures of the synthesized compounds were established from their analytical and spectral data.

Estimate of the long-range interactions between hydrophobic surfaces as applied to flotation of sulphide minerals

Using pyrite, chalcopyrite and sphalerite for exemplification, the forces of electrostatic repulsion and hydrophobic attraction between particles are estimated. Based on the experimentally obtained values of the induction time, the limit thickness of a wetting film is calculated to demonstrate the long-range behavior of the attraction forces between sulphides and an air bubble. It is established that the surface hydrophobicity of the tested sulphides increases under the action of a hydrophobic polymer and compounded collecting agents (isopropyl ethyl thiocarbamate and butyl xanthate). This fact enables enhancing the extraction of zinc and sulphide products from tailings of copper-zinc ore concentration.