JPH0316959A - Production of water-permeable paving material made from red mud as raw material - Google Patents

Abstract

PURPOSE:To improve water permeability by dehydrating red mud discharged from aluminum refining factories, then forming the dehydrated red mud into a granular shape, press forming the resultant grains and calcining the obtained blocks. CONSTITUTION:Red mud discharged from aluminum refining factories is dehydrated and dried utilizing waste heat and remaining heat of aluminum refining plants to provide caky red mud with 7-15% moisture content. The resultant caky red mud is then treated in a granulator and formed into granular red mud having 2.0-3.0mm grain diameter. The formed grains are subsequently dried utilizing waste heat of the refining plants to afford granular red mud with 5-8% moisture content. A calcining agent (e.g. feldspar powder) in an amount of 15-25wt.% is then added to the aforementioned granular red mud and the obtained mixture is press formed into the shape of blocks and calcined at 1000-1200 deg.C.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a method for manufacturing a water-permeable paving material using red mud discharged in large quantities at an aluminum smelting factory as a raw material. .

[Prior art and problems]

As is well known, in aluminum smelting plants, raw ore (bauxite) is concentrated after being leached with alkali. A large amount of red mud is discharged from the filtration separation process.

This red mud is a slurry that contains a large amount of water and is reddish-brown in color, making it extremely difficult to handle. Therefore, in the past, there was no recycling or reuse, etc.
It has been disposed of as industrial waste.

However, even when it is disposed of, it is in the form of a slurry as described above, and furthermore, because it is a colored waste, there are restrictions on where it can be dumped, and the disposal cost is high, which has become a social problem.

By the way, the chemical composition of this red mud is, as shown in Table 1 below, silicic acid (Sing), aluminum oxide (A
The main precepts are ferric oxide (Pe20s), titanium dioxide (Tint), etc. Calcium oxide (CaO), sodium oxide (Na20)
etc. In other words, its main precept is a substance that is the same as the raw material for ceramic building materials such as bricks and tiles, and is also plastic.

Table 1: Chemical composition of red mud The present inventor focused on this point and developed a paving material made from this red mud as a main raw material, especially a pavement with a permeable function that can replace conventional non-permeable paving materials. It was developed with the aim of providing blocks. This invention is the result of this research and development.

[Means to solve the problem]

Therefore, the method of manufacturing water-permeable pavement material using red mud as a raw material according to the present invention is as follows: (a) red mud discharged from an aluminium smelting factory,
First, it was dehydrated to a moisture content of 7 to 15%. In other words, the slurry-like red mud was transformed into a cake-like form.

(0) Next, the red mud that has been dehydrated in the form of a cake is passed through a granulator to obtain a particle size of 2. 0-5. It was molded into 0 mm granular red mud.

(c) This granular red mud was then pressure-formed into paving blocks based on the molding method used for bricks and tiles.

(2) Next, this pressure-formed block is burned at a temperature of 1
It is characterized by being baked and hardened at ,000 to L200°C and used as a so-called burning block for pavement.

〔Example〕

Further, the present invention will be specifically explained based on Examples.

The red mud used in this example was the red mud from Factory A shown in Table 1 above.

First, the red mud discharged from the aluminum smelting process was run through a dehydrator to transform it from a slurry to a cake.

Dehydrators include mechanical dehydration treatment methods such as play coat dehydration, centrifugal dehydration, and pressure press dehydration, but in this example, the secondary dehydration is first performed in a centrifugal dehydrator, and then the dehydration is carried out using waste heat from an aluminum smelting plant. The slurry was dried and dehydrated using residual heat to obtain a cake-like red mud with a water content of approximately 7 to 15%.

Next, this cake-like red mud is passed through a granulator to obtain particles with a particle size of 2.0~
It was shaped into granular red mud of 3r O mn+.

In the examples, a pressure granulation type briquette type granulator was used as the granulation means. In addition, when using a bun type granulator, the desired particle size is 2.0 to 5. It is difficult to granulate in the range of 0 mm, that is, 5'. It is easy to mold particles with a particle size of 2.0 to 5.0 mm. It is difficult to granulate so-called small particles within the range of 0 mm. Therefore, when granulating with a pan-type granulator, the cake-like red mud was once stirred and kneaded, then finely crushed, and then granulated in the pan-type granulator.

Next, the particle size is 2.0 to 5. Granular red mud shaped to 0 mm was dried using waste heat from a smelting plant. Then, it was made into granular red mud with a moisture content of 5 to 8%. As a result, red mud, which had been extremely difficult to handle,
It became easy to handle, and it was possible to suppress the increase in costs associated with reusing red mud.

Next, using this granular red mud as a raw material, a press was used to press and form paving blocks. At that time, in the example, 15 to 25% by weight of feldspar powder was added to the granular red mud as a sintering agent, and the mixture was stirred and mixed with a mixer.
It was made into a block of x 100 x 200mm.

When pressurizing or shaping with a press, a vibrating press or shaping machine is used, in other words, a mixture of the granular red mud as a raw material and feldspar powder as a sintering agent is fed into the mold using vibration force, and then It was then pressurized and shaped.

Note that instead of the feldspar powder as the sintering agent, bentonite I.(A1iz03.4SiO2.6H20) or glass powder may be used. In that case, the optimum amount of addition was 5 to 8% by weight relative to the granular red mud.

Finally, this pressurized and shaped block was dried and then put into a kiln to obtain a paving block that was baked and hardened at 1,000°C. Table 1 (3) below shows the physical properties of the paving blocks obtained by the above baking process.

As mentioned above, the red mud is first formed into granules, which are then shaped into blocks using a vibration pressurization method and then sintered. It has become a highly functional paving block.

In particular, when feldspar powder, bentonite, or glass powder is added and sintered as shown in the examples, they function as a binder to bind the red mud particles, and as shown in Table 2, they become porous. Pavement blocks with physical properties of high compressive strength were obtained.

〔Effect of the invention〕

This invention provides a water-permeable paving material using red mud, which has been an industrial waste and has been difficult to dispose of, as a raw material.The first point is that it greatly contributes to the effective use of resources.

Next, as a manufacturing method, the slurry-like material at the time of discharge was first dehydrated and transformed into a cake-like substance, which was then dried into a clay-shaped red mud, which was then made into a form that was easy to handle as a raw material for paving blocks. , the block manufacturing process is easier, and combined with the effective use of resources, compared to conventional water-permeable pavement made of open-grained asphalt,
An extremely economical permeable pavement can be provided.

In particular, the manufacturing process after forming into granular red mud is easy to perform on a production line, so paving blocks can be obtained at low cost.

Next, the paving blocks obtained through the burning process are extremely lightweight, have water permeability as mentioned above, and are reddish-brown in color, so they have functionality not found in conventional paving blocks. Can be used as colorful paving blocks.

In particular, the particle size of the granular red mud was set to 2.0 to 5.0 m, pressure molded, and sufficient water permeability was ensured after firing, making it the perfect paving material for shopping streets, parks, etc. blocks can be provided.

[Brief explanation of drawings]

The figure shows a manufacturing process diagram of a paving material using red mud as a raw material according to the present invention. Manufacturing process diagram

Claims (1)

[Scope of Claims] (a) A process of dehydrating red mud discharged from an aluminum smelting factory to a water content of 7 to 15%, (b) A process of dehydrating the dehydrated red mud to a particle size of 2.0 to 5.0 mm. (c) Pressure-forming the granular red mud into blocks; (d) Pressure-formed blocks into blocks of 1,000 to 1,200
A method for manufacturing a water-permeable paving material using red mud as a raw material, which comprises the steps described above, including the step of firing at ℃.