Preparation Of Fe-Cu-C Ternary Micro-electrolytic Material From Copper Slag And Its Degradation Of Benzohydroxamic Acid

As copper smelting waste slag,except a small part of it is used as raw material for cement production,most of it is deposited,causing land resource encroachment,water environment pollution and air environment and other problems.In this paper,the Fe-Cu-C ternary micro-electrolytic material was prepared from copper slag by carbothermal reduction method,and it was used to degrade benzohydroxamic acid（BHA）in mineral processing wastewater.The effects of preparation and degradation conditions on the BHA degradation efficiency of Fe-Cu-C were studied,and the preparation mechanism of Fe-Cu-C was explored by roasting temperature,roasting time and anthracite dosage.In addition,the properties of Fe-Cu-C and the reaction mechanism of BHA degradation were studied.The main research contents and conclusions are as follows:In the process of carbothermal reduction of copper slag,the reduction process of magnetite was as follows:Fe₃O₄→Fe O→Fe;Fe₂Si O₄ was more stable than Fe₃O₄ and required a higher roasting temperature to achieve reduction.The preparation conditions have a great influence on the performance of Fe-Cu-C degradation of BHA.The performance of Fe-Cu-C could be improved by increasing the roasting temperature,extending the roasting time and increasing the dosage of anthracite.Under the conditions of roasting temperature 1100℃,roasting time40 min and anthracite dosage 35%,Fe-Cu-C has the best degradation performance for BHA.Fe-Cu-C was characterized under the optimum preparation conditions.It was found that the iron minerals and copper minerals in the copper slag were reduced to iron and copper,and a supported ternary micro-electrolytic material with Fe-Cu-C alloy,Cu-Fe-Fe-C alloy,free carbon as the main active components and quartz as the carrier was formed.The dosage of Fe-Cu-C,initial p H of solution and initial concentration of solution all have significant effects on the degradation of BHA,while the temperature of solution has little effect on the reaction.When the dosage of Fe-Cu-C was 2.50g/L,the initial p H range was 4.0-9.0,the concentration of BHA was 50 mg/L and the temperature of solution was 28℃,the degradation efficiency of Fe-Cu-C can reach more than 86%.The addition of Na OH,Pb（NO₃）₂ and Na₂CO₃had no significant effect on the degradation efficiency of BHA,while Na₂Si O₃ inhibited the reaction.Under the conditions of Fe-Cu-C dosage of 2.50g/L,initial p H of solution 4.0,concentration of BHA of 50 mg/L and solution temperature of 28℃,after 60 min reaction,the degradation efficiency of BHA in co-existing reagent test was 91.07%,86.87%,88.52%and70.20%,respectively.In the actual simulation of the degradation of mineral processing wastewater,the degradation efficiency of BHA was still 73.50%.The results of TOC and COD of the reaction solution showed that Fe-Cu-C could degrade BHA,but could not completely mineralize it.GC-MS detection results showed that intermediates such as phenol,mesulfonamide,phthalic acid,acetic acid and fumaric acid were found.Combined with other test results and literature,two possible degradation pathways of Fe-Cu-C for BHA were deduced:1)The molecular complexes derived from Ph CO and Ph NHOH are formed successively by the fracture of C–N bond,and phenol products are formed under the action of micro-electrolysis,which are finally mineralized into CO₂and H₂O;2)Ph CONH is formed by N–O bond fission,and the intermediate products are mainly o-hydroxyphenylisocyanate and other o-benzoimide derivatives.The C–N bond is split to form HNO,and finally decomposed into N₂O and H₂O.