Impurity Removal Method of Silicate Solid Waste and Its Application

Abstract

The present application discloses the impurity removal method of silicate solid waste and its application. This method includes: (A) Heat and melt the silicate solid waste to be treated to form the melt, and stratify the melt during the reduction reaction; (B) An upper melt component obtained by the stratification is subjected to magnetic phase-induced crystallization to obtain a ferromagnetic solid; (C) The ferromagnetic solid goes through magnetic separation, and what remains is the solid waste after impurity removal. This impurity removal method can effectively reduce the main impurity content of the solid waste including iron oxide. The removed solid waste can be directly used for the preparation of high value-added materials such as insulating ceramics and micro-crystal glass.

Claims

1. An impurity removal method of silicate solid waste characterized by comprising the following steps: (A) Heat and melt a silicate solid waste to be treated to form the melt, and stratify the melt during reduction reaction; (B) An upper melt component obtained by the stratification is subjected to magnetic phase-induced crystallization to obtain a ferromagnetic phase solid; (C) The ferromagnetic phase solid is magnetically separated, and the remaining phase is the solid waste after impurity removal.

2. The impurity removal method according to claim 1, the temperature of the heating and melting ranges from 1400 to 1600° C.

3. The impurity removal method according to claim 1, a container used for the silicate solid waste to be treated is made of graphite.

4. The impurity removal method according to claim 1, an equipment for the heating and melting is an electromagnetic induction heating furnace.

5. The impurity removal method according to claim 4, the electromagnetic induction heating furnace is provided with a graphite lining for accommodating solid silicate waste to be treated.

6. The impurity removal method according to claim 1, the reduction reaction time ranged from 2 to 5 min.

7. The impurity removal method according to claim 1, the temperature of the magnetic phase-induced crystallization is 850˜950° C., and the magnetic field strength is 0.1˜10 T.

8. The impurity removal method according to claim 1, the cooling rate of the magnetic phase-induce temperature is 0.5˜1° C./min.

9. The impurity removal method according to claim 1, before step (A), the silicate solid waste shall be crushed until a particle size shall not exceed 200 μm, and the silicate solid waste crushed shall be pressed into blocks.

10. The impurity removal method according to claim 1, the solid waste after this impurity removal method can serve as a raw material for silicate products.

Description

EXAMPLE 1

[0035] (Coal Gangue as the Silicate Solid Waste)

[0036] The main components of the coal gangue to be treated are shown in Table 1 below:

TABLE-US-00001 TABLE 1 SiO.sub.2 Al.sub.2O.sub.3 CaO MgO TFe.sub.2O.sub.3 MnO Na.sub.2O P.sub.2O.sub.5 Total coal gangue 54.18 29.07 2.29 1.40 12.50 0.18 0.07 0.31 100

[0037] Step 1: The coal gangue of the above components was broken up and ball-milled for 2h with a grinding speed of 500 r/min. The powder left was pressed into wafer with a pressure of 15 Mpa and a pressure retention time of 1 min, with a diameter of 20 mm and a thickness of 10 mm.

[0038] Step2: The nubbly raw material was put into a graphite crucible with an internal diameter of 34 mm and an outer diameter of 46 mm. Afterwards, the graphite crucible was put into a fire-resistant sleeve, and both of them were put together into the electromagnetic induction coil, with a diameter of 10 mm and cooling water inside. After the cooling water was in, the electromagnetic induction heating furnace was started.

[0039] Step3: The temperature in the above furnace was controlled at 900° C., and the magnetic field strength was 5T. The upper melt was transferred to the furnace with a controlled cooling rate of 0.5° C./min until the melt was cooled down to room temperature.

[0040] Step4: After the cooled melt was crushed, the particle size should be lower than 75 and go through the magnetic separator with a magnetic field strength of 80 KA/m to complete the magnetic separation. Afterwards, the composition of the solid after impurity removal was analyzed, and the results are shown in Table 2:

TABLE-US-00002 TABLE 2 Composition after impurity removal (wt %) SiO.sub.2 Al.sub.2O.sub.3 CaO MgO TFe.sub.2O.sub.3 MnO Na.sub.2O P.sub.2O.sub.5 Total solid after 53.83 42.04 1.76 1.70 0.32 0.15 0.20 0 100 impurity removal

EXAMPLE 2

[0041] (A mixture of coal gangue, fly ash and steel slag as the silicate solid waste)

[0042] Step 1: Crush and mix the coal gangue (23.5%), fly ash (36.5%) and steel slag (40%). The mixture was ball-milled for 2h with a grinding speed of 500 r/min. The powder left was pressed into wafer with a pressure of 15 Mpa and a pressure retention time of 1 min, with a diameter of 20 mm and a thickness of 10 mm. The composition of coal gangue, fly ash, steel slag and the mixture are shown in Table 3.

TABLE-US-00003 TABLE 3 Composition of coal gangue, fly ash, steel slag and the mixture (wt %) SiO.sub.2 Al.sub.2O.sub.3 CaO MgO TFe.sub.2O.sub.3 MnO P.sub.2O.sub.5 Na.sub.2O Total fly ash 58.17 37.50 0.23 0.30 3.52 0.10 0.10 0.08 100 coal gangue 52.99 41.43 1.82 0.44 3.04 0.01 0.18 0.09 100 steel slag 15.47 2.62 43.25 6.80 26.60 3.09 2.17 / 100 mixture 39.20 24.98 18.02 2.95 12.58 1.26 0.96 0.05 100

[0043] Step2: The nubbly raw material was put into a graphite crucible with an internal diameter of 34 mm and an outer diameter of 46 mm. Afterwards, the graphite crucible was put into a fire-resistant sleeve, and both of them were put together into the electromagnetic induction coil, with a diameter of 10 mm and cooling water inside. After the cooling water was in, the electromagnetic induction heating furnace was started, and the frequency was set to 40 KHZ. The current was 30 A in 1-5 min and then changed to 35 A in 5-10 min. The reactant started to melt at 10 min, and the temperature was about 1500° C. The upper melt was removed after 15 min of the reaction.

[0044] Step3: The temperature in the above furnace was controlled at 900° C., and the magnetic field strength was 5T. The upper melt was transferred to the furnace with a controlled cooling rate of 0.5° C./min until the melt was cooled down to room temperature.

[0045] Step4: After the cooled melt was crushed, the particle size should be lower than 75 μm, and go through the magnetic separator with a magnetic field strength of 80 KA/m to complete the magnetic separation. Afterwards, the composition of the solid after impurity removal was analyzed, and the results are shown in Table 4:

TABLE-US-00004 TABLE 4 Composition after impurity removal (wt %) SiO.sub.2 Al.sub.2O.sub.3 CaO MgO TFe.sub.2O.sub.3 MnO P.sub.2O.sub.5 Na.sub.2O Total solid after 40.83 31.41 22.74 3.11 0.49 1.31 0.02 0.09 100 impurity removal

[0046] After two times of impurity removal, the iron content in the solid waste was reduced from 12.58% to 0.49%, and the recovery rate reached 96.10%. At the same time, the P.sub.2O.sub.5 content in the solid waste was reduced from 0.96% to 0.02%.

[0047] The above are only preferred exploit examples of the present invention. The scope of protection of this invention is not limited thereto. Within the technical scope as disclosed by the present invention, the changes or replacement that are easily conceivable for anyone familiar with this field should be covered by the protection scope of the invention.