Research On The Binder For Pellets Based On Full Oxygen Metallurgy Non-blast Furnace Ironmaking Process Conditions

Compared with the traditional pelletizing process,since the Full Oxygen Metallurgy non-blast furnace ironmaking process uses pulverized coal and pulverized ore pellet directly by "light pelletization" and then directly into the furnace,the new process eliminates the high-temperature roasting,which puts forward new requirements for the strength of carbon-containing pellets in cold state,and the binder is the key to achieve this purpose.Based on this,this paper uses bentonite,industrial molasses and organic binder HC(oxalic acid)to prepare carbon-containing pellets.Due to the TFe and high basic oxide content in converter dust,it can be used as a secondary resource to produce cold-consolidated pellets.This article is aimed at using converter dust with organic binder HC as a kind of composite binder to produce high-strength cold consolidated carbon-containing pellets.Firstly,this paper explores whether the organic binder HC can replace the traditional binder to produce pellets that meet the production requirements.In this process,the process parameters for preparing pellets are preliminary obtained through single factor investigation experiment,and the influence degree of the process parameters of pellet preparation are determined by orthogonal experiment as follows:the moisture content is selected as 6%;pelletizing pressure is 7 MPa;ore powder 200 mesh(that is,less than 0.074 mm particle size)pass rate reaches 80%;the carboncontaining pellets with C/O=1 were selected.In addition,through comparative experiments and the thermogravimetric analysis organic binder HC,combustion mass loss,porosity,specific surface area and infrared spectroscopy test analysis of the organic binder HC have fully proved the effectiveness of the organic binder HC.SEM image analysis shows that the organic binder HC could completely infiltrate near the iron ore particles and most of them are embedded in the ore particles,which significantly improves the dropping strength.On this basis,the use of converter dust with organic binder HC as a kind of composite binder of carbon-containing pellets using iron ore powder and coal powder as raw materials is explored.The mechanism is mainly divided into two points:The first point is that the Ca(OH)2 in the digested converter dust is easy to solidify with CO2 in the air,and it can be used as pellet binder.The second point is that the digestion rate of f-CaO in the dry converter dust is very slow,and the digestion reaction in the natural state is not complete.Directly pelletizing will gradually generate the expansion stress,inside the pellets,resulting in the pellets cracking.Therefore,in order to improve the strength of the carbon-containing pellets prepared by this method,it is necessary to add an organic binder HC to stabilize the f-CaO component in the undigested completely converter dust.Through chemical calculation analysis and thermogravimetric analysis,the feasibility analysis of the method of using converter dust with organic binder HC as a kind of composite binder was carried out,and its rationality was proved.And by observing the macro morphology and micro morphology of carbon-containing pellets after reduction,it is proved that the carbon-containing pellets prepared by converter dust partly replacing the iron ore concentrate powder meet the requirements for raw material processing of the national key research and development plan projects"Development and Demonstration of Efficient and Clean Production Technology Under Full Oxygen Metallurgy ",and the requirements for the carbon-containing pellets’strength of the grate-rotary kiln reduction equipment.