| With the rapid development of China’s economy, increasing demand for primaryaluminum, declining domestic bauxite resources. How to precipitate dissolvedaluminum from the solution, how to use the solution to re-back production has becomean urgent need to achieve sustainable development of circular economy. However, thereis no effective way to solve so far. In this paper, the main component don’t be affectedin the chemical milling solution, then it will remove the dissolved aluminum from thechemical milling solution and chemical milling solution used in aluminum recyclingand re-back to the purpose of milling process.Various substances in Aluminum chemical milling solution is measured qualitativeand quantitative analysis, And the removal of dissolved aluminum method isexperimental proof, the removal of industrial application method was first proposed.Specific results were as follows:（1） using a variety of methods to remove dissolved aluminum from chemicalmilling solution and select the one best method.Author mainly use air aeration method, ultrasonic method, CaO crystallization,water dilution method, Al （OH）3crystallization to remove dissolved aluminum from thechemical milling solution. The results show that: dissolved aluminum can not beremoved by air aeration method and ultrasonic method; CaO crystallization can be usedto remove dissolved aluminum, The removal rate can reach40%, but this method willincrease Ca ions in solution which were not exist in the original solution; Water dilutionmethodcan destroy the dynamic balance between sodium hydroxide and dissolvedaluminum in the mixed solution, causing dissolved aluminum is crystallized;Al（OH）3crystallization be able to achieve50%removal of dissolved aluminum, and no newchemicals added to the solution so that it will not change the original ratio.at the sametime sodium hydroxide, sodium sulfide and triethanolamine loss rate less than10%.With experimental results, the author obtained new experimental method—pure water dilution crystallization.（2） pure water dilution crystallization was system analysis by single factorexperiments and orthogonal test,the optimal experimental conditions of the method andparameter will be determined.1) The single factor experiment results show that:The best dilution was diluted to1times-2times，the removal rate of dissolved aluminum can be more60%; the whitecrystalline solid substance precipitated by X-diffraction analysis shows that99%of thecomposition is aluminum hydroxide crystals.The most suitable temperature range is controlled at between35℃-55℃, atemperature range in which the removal of aluminum dissolved in30%-50%, and theresponse cycle is8-10days.Al（OH）3nuclei come from the chemical milling solution itself, and thus will notintroduce any of the other impurities.The amount of nucleus is from0.5times to1timesfor the quality of dissolved aluminum. the experimental reaction cycle is only5-6days,the removal rate of dissolved aluminum is more than50%.Speed of mixer has little effect on the decomposition. As long as the nucleus ofaluminum hydroxide suspended in the solution.2) orthogonal experimental results show that:Author use Design-Expert software7.0.0to design and analysis the orthogonalexperiment results showed that: dilution factor, temperature and nucleation is not theamount of interaction between the three, However, the three of factors are a significantimpact. the influence of three factors were as follows: dilution factor> temperature>nuclei.dilution factor is the most significant for pure water dilution crystallization.The best experimental parameters are the temperature is35℃,2times dilution,nucleation addition level of1.5times,removal of dissolved aluminum were stabilized atmore than50%.（3） According to the orthogonal experiment, Author conducted a small pilot test.The final result consistent with the experimental demonstration. As small scale test to beapplied to engineering Small scale equipment to be used in engineering practice and theactual production, by increasing the temperature shortened the reaction time to48hours,the removal of dissolved aluminum in solution at about35%. |
