A kind of phosphogypsum is prepared the technique of building gypsum plasterTechnical field
The present invention relates to a kind of waste residue and process and utilize technical field, particularly relate to a kind of two-step approach and realize phosphogypsum and under suspended state, dry, dewater, prepare the production technique of building gypsum plaster.
Background technology
Phosphogypsum is that phosphoric acid by wet process and Phosphate Fertilizer Industry are produced the solid waste of discharging, and its main component is that CaSO4.2H2O(content is more than 90%).Produce one ton of phosphoric acid and will produce the phosphogypsum slag of five tons of left and right, China's production of phosphate fertilizer will be discharged tens million of tons of phosphogypsums every year, needs a large amount of soils to stack, and environment is caused to severe contamination simultaneously.Gypsum discharges the environmental protection pressure forming has become one of important restriction factor of Phosphate Fertilizer Industry development.
Phosphogypsum is trade waste, is also valuable resource.Phosphogypsum particle shaping, drying and dewatering can become the gypsum for building powder that meets national standard after processing.This technique has been eliminated the pollution of the industry by-product gypsums such as phosphogypsum to environment, turns waste into wealth, and also can economize on resources.Therefore, the chemical engineering industry of by-product gypsum and building materials industry can be combined the exploitation of the industry by-product gypsums such as phosphogypsum, accomplish phosphate fertilizer and phosphoric acid etc. industry without waste sludge discharge.
The production of building gypsum plaster has kinds of processes.Press type of heating, be divided into indirect heating technique and direct heating technique; Press calcined dehydration speed, be divided into calcining process and quick calcining process at a slow speed; Press discharge method, can be divided into batch production technique and continuous production processes.
Before nineteen sixties, taking tradition slowly burning type intermittence frying pan and outer burning formula rotary kiln as main.Later stage in the sixties, aforesaid device has been carried out to technological transformation, the seventies, by intermittence frying pan develop into continuous frying pan, after the eighties, developed into again taper frying pan; Rotary kiln also develops into inside burning type calcining from outer burning formula; For promoting the technical progress of building gypsum plaster industry, improve the travelling speed of gypsum building material product production line, develop again in recent years air-flowing type quick calcining process.As a whole, gypsum calcination technique is along from intermittent take-off to continuous discharge, from indirect heating to direct heating, progressively develop from being dewatered at a slow speed the trend of fast dewatering.
At present, the medium-sized and small enterprises of China to be adopted interior burning or burns rotary kiln, intermittence or continuous frying pan and fluidizing furnace etc. outward and produce, and scale is less, and auxiliary facility is unsound, and quality product is stable not, and energy consumption is higher.In recent years, 100,000 tons of above fluidizing furnaces of the independently developed annual output of China, existing several of direet-heating type rotary kiln have dropped into production (processing parameter still awaits optimizing).
Summary of the invention
The object of this invention is to provide a kind of technique of utilizing phosphogypsum to prepare building gypsum plaster, this process using trade waste is as raw material, and technological process is simple, and it is convenient to control, and product performance are superior stable, meet the requirement of standard GB/T 9776-2008 completely.
The object of the invention to solve the technical problems realizes by the following technical solutions.The phosphogypsum that utilizes proposing according to the present invention is prepared the technique of building gypsum plaster, comprises the following steps:
A. the feeding of phosphogypsum raw material: phosphogypsum raw material quantitatively feeds charging chute by special feeding machine;
B. dry and the thermal source that dewaters: adopt hotblast stove that gas thermal source is provided, gas temperature is controlled at 350 DEG C ~ 600 DEG C;
C. dry, the fine grinding of phosphogypsum, select powder: phosphogypsum raw material has been concentrated particle dispersion, levigate, dry and classification process in Vertical Mill device, the dusty gas that Vertical Mill device is discharged enters cyclonic separator, realize gas solid separation, gas flow temperature is controlled at 90 DEG C ~ 140 DEG C; The intermediate material that goes out Vertical Mill device is dihydrate gypsum, and free water content is less than 5%; Described dusty gas is discharged through induced draft fan after gathering dust by dust-precipitator;
D. the suspended state of phosphogypsum dehydration: dried intermediate material enters the dehydration of suspended state dehydration furnace, and the temperature out of dehydration furnace is controlled at 160 DEG C ~ 230 DEG C; Then through cyclonic separator gas solid separation, the principal goods of collection material is semi-hydrated gypsum powder mutually, and total water content is controlled at 3% ~ 10%; Gas enters Vertical Mill device, as the part of heat energy of drying.
E. ageing: collect the semi-hydrated gypsum powder obtaining and send in aging bunker, ageing 1 ~ 5 day, becomes building gypsum plaster.Products obtained therefrom reaches the requirement of the national standard GB/T 9776-2008 of industrial building gypsum plaster.
The object of the invention to solve the technical problems also can be applied to the following technical measures to achieve further.
Described phosphogypsum raw material can be industry byproduct gypsum or the plaster of paris such as fluorgypsum or other type gypsum.CaSO in various raw materials4.2H2the content of O is 60% ~ 100%, SiO2content is 0% ~ 30%.
In described processing step B, hotblast stove can be fire coal, combustion gas or the fuel oil type of furnace, also can be without hotblast stove, and utilize the high-temperature tail gas of other commercial runs discharges as thermal source.
In described processing step C, the material mean particle size after vertical mill grinding is controlled within the scope of 15 μ m ~ 60 μ m.
In described processing step C, dust-precipitator can be belt dust-precipitator or dust precipitator.
Described in processing step C, dehydration furnace adopts material stove outer circulation mode, and its solid circulating rate is controlled.
Process system of the present invention is negative-pressure operation, the device interior Negative Pressure Difference that power resources form in induced draft fan.
The method that phosphogypsum of the present invention is prepared building gypsum plaster at least has following advantages:
1) exploitation to industry by-product gypsums such as phosphogypsums, can combine the chemical engineering industry of by-product gypsum and building materials industry, realize phosphate fertilizer and phosphoric acid etc. industry without waste sludge discharge.
2) in technical process, core procedure C can realize the according to target control of phosphogypsum powder particle level, and granularity control is convenient.
3) in technical process, the heat and mass transfer process in core procedure C-D is all to carry out under suspended state, has greatly improved gas-solid condition of transmitting, has improved thermo-efficiency and the reaction efficiency of system.The fundamental research in early stage proves that suspended state dehydration can complete rapidly in 15s.
4) the C step that enters the relatively high waste gas of temperature that D step is discharged continues to utilize, and final spent air temperture of discharging, lower than 120 DEG C, significantly reduces with conventional dehydration technique phase specific fuel consumption.
5) the modern control device of this process using is carried out the control of temperature and flow, and level of automation is high, and product performance are stable, is easy to extensive tissue and produces.
Brief description of the drawings
Fig. 1 is process schematic representation of the present invention, and the dotted line with arrow in figure represents airflow route, represents material route map with the solid line of arrow.1. feed system; 2. hotblast stove; 3. Vertical Mill device; 4. dehydration furnace; 5. finished product bin; 6. centrifugal blower; T1 is 450 DEG C; T2 is 180 DEG C; T3 is 110 DEG C.
Embodiment
The technique means of taking for reaching predetermined goal of the invention for further setting forth the present invention, below in conjunction with accompanying drawing and preferred embodiment, the technique of being prepared by the two-step approach phosphogypsum proposing according to the present invention to building gypsum plaster is described further.
Concrete technical scheme of the present invention is as follows:
Process system of the present invention is negative-pressure operation, the device interior Negative Pressure Difference that power resources form in induced draft fan.Formed by drawing-in device, Vertical Mill device, suspended state dehydration reaction stove, aging bunker and dust arrester installation etc., comprise following processing step:
A: the feeding of phosphogypsum raw material.Phosphogypsum raw material quantitatively feeds the charging chute in C step by special feeding machine.According to industrial scale, the specification of feeding machine can be 300 ~ 6000t/d (ton/sky).
B: dry and dehydration thermal source.Adopt hotblast stove to provide gas thermal source for C and D step.One preferably temperature control embodiment be that gas temperature is controlled within the scope of 450 ± 20 DEG C.
C: dry, the fine grinding of phosphogypsum, select powder.Phosphogypsum raw material has been concentrated particle dispersion, levigate, dry and classification process in Vertical Mill device.One preferably temperature control parameter be Vertical Mill discharge dust-contained airflow temperature be controlled within the scope of 110 ± 10 DEG C, enter cyclonic separator, realize gas solid separation.The intermediate material that goes out Vertical Mill is dihydrate gypsum, and free water content is less than 3%.After gas enters dust-precipitator and gathers dust, discharge through induced draft fan.
D: the suspended state dehydration of phosphogypsum.Dried phosphogypsum powder enters the dehydration of suspended state dehydration furnace, and a temperature out that preferably embodiment is dehydration furnace is controlled at 190 ± 10 DEG C.By cyclonic separator gas solid separation, the principal goods of collection material is semi-hydrated gypsum powder mutually, and under embodiment preferably, material total water content is controlled within the scope of 4%-6%.Gas enters Vertical Mill device, as the part of heat energy of drying.
E: collect the semi-hydrated gypsum powder that obtains and enter in aging bunker, one preferably embodiment be the ageing through 2 ~ 3 days, become building gypsum plaster, reach the requirement of the national standard GB/T 9776-2008 of industrial building gypsum plaster.
In processing step C of the present invention, the grinding fineness of phosphogypsum material and select the parameters such as powder fineness adjustable according to processing requirement.One preferably embodiment be that the median size of terra alba is controlled at 15 μ m ~ 40 μ m.
In processing step D of the present invention, the dehydration temperaturre of phosphogypsum material is adjustable according to processing requirement.
In technical process of the present invention, systematic air flow, system are that device interior sectional wind velocity is adjustable, and regulative mode can be for arranging valve or induced draft fan being adopted to frequency control way on pipeline.
In processing step D of the present invention, phosphogypsum suspended state reactor adopts material stove outer circulation mode, and its solid circulating rate is controlled.One preferably embodiment be that internal circulating load is controlled at 10% left and right.
In technical process of the present invention, the air-flow that enters step C can be step D expellant gas, can be also the gas mixture of the high-temperature gas of step D and hotblast stove discharge, can carry out by the valve in respective line the configuration of gas flow.One preferably embodiment be that effective heat content that gas mixture carries meets the dry heat requirement of phosphogypsum, step C expellant gas temperature is maintained in the scope of 110 ± 10 DEG C.
The above, it is only preferred embodiment of the present invention, not the present invention is done to any pro forma restriction, although the present invention discloses as above with preferred embodiment, but not in order to limit the present invention, any those skilled in the art, do not departing within the scope of technical solution of the present invention, when can utilizing the technology contents of above-mentioned announcement to make a little change or being modified to the equivalent embodiment of equivalent variations, in every case be not depart from technical solution of the present invention content, any simple modification of above embodiment being done according to technical spirit of the present invention, equivalent variations and modification, all still belong in the scope of technical solution of the present invention.