TWI607092B - Slag processing method - Google Patents

Description

Slag treatment method

The invention relates to a slag treatment method, in particular to a slag treatment method for integrated stabilization and metal recovery.

In the production process, the steelmaking plant will produce waste slag that can be recycled and reused. The slag itself can be used as raw material for cement or cement products, such as wave block, street brick or concrete raw materials, etc. During the treatment, a small amount of molten steel will be poured out with the slag, and in addition to reducing the pollution of the environment, the metal can be used as a raw material for the steelmaking plant, thereby reducing the production cost, and thus the process of treating the slag Metal recovery is required. However, when the slag contains residual unreacted free calcium oxide (Free CaO), the composition will expand with time and adsorb moisture, resulting in expansion and cracking of the subsequently produced cement product. Therefore, the slag recovered by metal still needs to be stabilized before it is made into a product to control the amount of expansion, and thus meet the requirements of the current regulations for stability.

At present, the traditional slag internal metal recovery method is as follows: the slag is crushed by a masher, and after passing through the sieving, the metal is magnetically selected from the slag. However, the slag crushed by the masher has a particle size of more than 15 mm, so that a large amount of slag is attached to the metal to be smelted, so that when smelting is performed, additional energy is required to melt the slag attached to the metal, and Reduce the purity of metal recovery. In addition, for the reasons mentioned above, the slag needs to be stabilized before use to control the expansion ratio. Therefore, after the metal recovery, additional stabilization such as a smoldering method, a drum method, or a hot slag modification method is required. The process, due to the inability to integrate with the metal recycling process, has resulted in more complicated processes and increased time.

Accordingly, it is an object of the present invention to provide a slag processing method that integrates a stabilization process and a metal recovery process to simplify the process.

Thus, the slag processing method of the present invention comprises a rod grinding step, a magnetic separation step, and a sieving and dehydrating step.

In the rod grinding step, the crushed slag is sent to a rod mill filled with hot water, and the temperature of the hot water is 40 ° C to 100 ° C. In the magnetic separation step, the residual metal in the rod milled slag is selected. In the sieving and dehydration step, the slag after magnetic separation is classified according to the particle size, and after dehydration and sieving, the stabilized slag is obtained.

The effect of the present invention is that the rod mill can grind the broken slag to be finer, so that the metal contained in the slag is easily recovered. In addition, by adding hot water to the rod mill, the free calcium oxide remaining in the slag can be fully reacted into calcium hydroxide, and the effect of stabilization can be achieved. The invention integrates the metal recovery and stabilization process, so that the treated slag can be directly utilized, effectively shortening the process time and reducing the operation cost.

Referring to Figures 1, 2 and 3, an embodiment of the slag processing method of the present invention comprises a rod grinding step 11, a magnetic separation step 12, and a sieving and dehydrating step 13. Before carrying out the present embodiment, the slag 20 is usually sieved by a tilting vibrating screen 21, and the slag 20 exceeding 60 mm or more is sent to a shredder 22 for crushing, thereby performing preliminary crushing of the slag 20.

In the rod grinding step 11, the crushed slag 20 is sent to a rod mill 23 for grinding, and the rod mill 23 is loaded with a plurality of steel rods 232 inside a drum 231 as shown in FIG. The steel rods 232 are driven by rotating the drum 231, and the steel rods 232 that are driven to the highest point are dropped in a falling state, thereby smashing the slag 20 entering the drum 231. The rod mill 23 is filled with hot water 3 controlled at 40 ° C ~ 100 ° C, so that residual unreacted free calcium oxide in the slag can be fully reacted into calcium hydroxide, and the pressure control in the rod mill 23 The reaction rate can be increased from 0.3 MPa to 0.5 MPa. The particle size of the slag 20 after grinding in the present invention is preferably less than 5 mm, and is sufficiently stabilized. Since the particle size of the slag 20 is too large, it is unfavorable for recycling. Therefore, the present invention limits the slag 20 particle size to 5 mm or less, which not only enhances the subsequent magnetic separation step 12 The purity of the recovered metal also accelerates the efficiency of stabilization. Specifically, the particle size of the slag 20 after the polishing in this example is 1 mm or less. Table 1 below shows the percentage of free calcium oxide after the injection of different temperatures (or no injection) of hot water 3 in the rod mill 23, as can be clearly seen from the results of Table 1, soaking hot water 3 and operating 2 After hours (whether 50 ° C or 90 ° C), it is effective to reduce the free calcium oxide component relative to the unbuffered hot water 3, thereby reducing the problem of subsequent expansion of free calcium oxide to cause swelling. Settling effect. It can be seen from Table 1 that the hot water 3 at 90 ° C can better stabilize the effect.

Table I         <TABLE border="1" borderColor="#000000" width="85%"><TBODY><tr><td> water temperature</td><td> particle size</td><td> free state calcium oxide Content (%) </td></tr><tr><td> Unbleached water</td><td> ≤1mm </td><td> 2.14 </td></tr><tr>< Td> 50°C </td><td> ≤1mm </td><td> 1.60 </td></tr><tr><td> 90°C </td><td> ≤1mm </td> <td> 0.97 </td></tr></TBODY></TABLE>

Next, the magnetic separation step 12 is performed, and the rod-milled slag 20 is passed through a magnetic separator 24 to recover the residual metal in the slag 20, and the slag 20 has a particle size of 1 mm or less, thereby facilitating recovery and reducing The phenomenon of adhering the slag 20 to the residual metal selected by suction increases the purity of the recovered metal to 95% or more. Finally, in the sieving and dehydration step 13, the magnetically slag slag 20 is classified by a spiral classifier 25 according to the particle size, and the spiral classifier 25 returns the slag 20 having a substandard particle size back to the rod mill 23. The grinding is carried out, and the slag 20 having a particle size conforming to the standard will float in the water and overflow to a vibrating dewatering screen 26, and after the screening by the vibrating dewatering screen 26, the stabilized slag 20 can be obtained. In addition, the remaining slurry in this embodiment can be treated through a concentration tank 27 and a ceramic vacuum filter 28 to obtain pure recovered water and improve the recovery rate. It should be particularly noted that the aforementioned particle size standard is 5 mm or less, and after the inspection, the slag 20 treated by the present embodiment can be directly used according to the requirements of the current regulations for the slag stabilization.

Through the rod grinding step 11, the particle size of the slag 20 can be reduced to less than 5 mm, and the purity of the recovered metal can be improved. In the present embodiment, the particle size can be reduced to more than 95%, and the purity of the recovered metal can be as high as 95% or more. The hot water 3 is added to the grinding step 11, and the free calcium oxide can be sufficiently reacted into calcium hydroxide to achieve the effect of stabilization. The time taken for the slag 20 to pass through the rod grinding step 11, the magnetic separation step 12, and the screening and dehydration step 13 is within two hours, and the expansion ratio conforms to regulatory standards, so that the stabilization process is not required. Direct use.

In summary, the present invention effectively integrates metal recovery and stabilization, reduces operating costs and shortens the processing time, and the expansion ratio of the treated slag 20 can be directly utilized in accordance with the laws and regulations, and can ensure the quality of the reused product. Therefore, the object of the present invention can be achieved.

However, the above is only the embodiment of the present invention, and the scope of the invention is not limited thereto, and all the equivalent equivalent changes and modifications according to the scope of the patent application and the patent specification of the present invention are still The scope of the invention is covered.

11‧‧‧ rod grinding step
12‧‧‧Magnetic selection steps
13‧‧‧Screening and dewatering steps
20‧‧‧ slag
21‧‧‧Tilting vibrating screen
22‧‧‧masher
23‧‧‧ rod mill
231‧‧‧Roller
232‧‧‧Steel rod
24‧‧‧ magnetic separator
25‧‧‧Spiral classifier
26‧‧‧Vibration dewatering screen
27‧‧‧Concentration pool
28‧‧‧Ceramic vacuum filter
3·‧‧‧ hot water

Other features and advantages of the present invention will be apparent from the embodiments of the present invention, wherein: FIG. 1 is a flow chart illustrating one embodiment of the slag processing method of the present invention; FIG. 2 is a flow chart, further The process flow of the embodiment is illustrated; and FIG. 3 is a schematic view showing one of the rod mills in the rod grinding step.

11‧‧‧ rod grinding step

12‧‧‧Magnetic selection steps

13‧‧‧Screening and dewatering steps

Claims (6)

A slag processing method comprising: a rod grinding step of feeding the crushed slag into a rod mill filled with hot water, the temperature of the hot water being 40 ° C ~ 100 ° C; a magnetic separation step, the rod The residual metal in the slag after the grinding is selected; and a sieving and dehydrating step, the slag after the magnetic separation is classified according to the particle size, and after dehydration and sieving, the stabilized slag is obtained. The slag processing method according to claim 1, wherein in the rod grinding step, the pressure in the rod mill is controlled to be between 0.3 MPa and 0.5 MPa. The slag processing method according to claim 1, the total time taken for the rod grinding step, the magnetic separation step, and the sieving and dehydrating step is not more than two hours. The slag processing method according to claim 1, wherein in the rod grinding step, the rod mill grinds the slag to a particle size of 5 mm or less. The slag processing method according to claim 1, wherein in the sieving and dehydrating step, the slag having a particle size that does not meet the standard is returned to the rod mill, and the slag conforming to the standard will float in the water and overflow. To the screening point. The slag processing method according to claim 5, wherein the standard is a particle size of 5 mm or less.