Mixing-Buring Of Coal Slime And Rice Husk And High Valueutilization Of Ash

In recent years,with the country’s attention to energy conservation and emission reduction,the clean use of coal is more stringent requirements.At the same time,due to the poor quality of raw coal in our country,we can get better quality coal by washing raw coal.The by-product of raw coal after separation is coal slime,which is difficult to use because of its high moisture content,high ash content,high viscosity and low calorific value.Rice husk,as a waste in agricultural production,is also an excellent renewable energy with high volatile content and fast ignition.But pure rice husk burning has caused slagging problem in boiler.Can rice husk and slime combustion have the advantages of both? Therefore,coal slime and rice husk will be used for co-combustion in this paper.Through various experiments and testing methods,the combustion characteristics,gas products and phase changes of coal slime and rice husk and their mixtures will be studied.Meanwhile,the preparation of silica white from coal ash and cement from fly ash were studied.Coal slime and rice husk were mixed according to a certain mixing ratio.The combustion characteristics of coal slime,rice husk and mixture were understood through thermograin-weight experiment,and the comprehensive combustion index was used to evaluate the combustion performance of each sample,as well as the influence of heating rate on sample weight loss.The 40 percent of the mixture was the lowest average activation energy.The Coasts-Redfern scored an integral value of 31.18 k J/mol,and daem-Miura scored 111 k J/mol,both of which were lower than the average activation energy for the two components burned separately.According to the Analysis of the gas after combustion by Fourier infrared spectrum,after the addition of rice husk,the release amount of CO₂,CO and H₂O of the mixed sample is reduced,and the release time is also advanced.Coal slime and rice husk are mixed according to certain mixing ratio.Through the mixing experiment of horizontal tubular furnace,the combustion characteristics of sample ball under different furnace temperature and mixing ratio are understood.The change of central temperature of sample particles can be divided into three stages: the first stage is the rapid heating stage of sample particles,the second stage is the gradual rise of central temperature of coal slime particles,and the third stage is the burning-out stage.The whole combustion process of coal slime particles can be divided into two stages: the first stage is the volatile ignition stage of coal slime and the second stage is the fixed carbon combustion stage of coal slime.The whole combustion process of rice husk particles can be divided into two stages: the first stage is the volatile ignition stage of rice husk,and the second stage is the fixed carbon combustion stage of rice husk.With the increase of rice husk mixing ratio,the flame formed by volatiles combustion increased.The volatiles of rice husk in the mixed sample were separated first than those of coal slime.The main stage of mixed sample combustion in the burning stage of coke.This stage consumes several times or even ten times of the volatile combustion time.Increasing rice husk ratio and increasing furnace temperature can accelerate the combustion process.The ignition delay time and burnout time became shorter with the increase of rice husk mixing ratio.Increasing furnace temperature can also reduce ignition delay and burnout time.The addition of rice husk is beneficial to fire and burn out.For the treatment of ash,sodium hydroxide solution and coal slime ash are mixed by alkali dissolution test.The concentration of sodium hydroxide solution is 2mol/L,the reaction time is 2h,the reaction temperature is 70℃,the filtrate is filtered and the p H value is adjusted,Some products can be obtained.X-ray diffraction（XRD）proves that this product is white carbon black.This solution is simple and easy to save energy.At the same time,the test results of making cement by ash without adding rice husk（which is similar to the material composition after coal slime ash extraction of white carbon black）show that the main proportion of clinker produced is close to that of sulfoaluminate cement.Indices,the main components such as Ca₂ SiO₄ and Ca₄Al₆O₁₂SO₄ were also detected in the clinker.It can also explain that the material after the extraction of white carbon black from coal slime ash can also be used to make cement,which can realize the comprehensive utilization of ash samples.