DE19707339A1 - Treating red sludge from mining operations, by mixing with chalk and water - Google Patents

Abstract

In a process to treat red sludge discharged with water from mining operations and render it fit for disposal at an associated coal-fired power station, the novelty is that:(a) the red sludge is mixed with other substances promoting the desulphurisation of smoke gases and a suspension of chalk; (b) the resulting mixture is employed in a smoke gas washer at a coal-fired power station; (c) the red sludge and ground chalk are placed in a holding basin or tank containing an absorption agent where they are mixed; (d) the red sludge is mixed with the chalk in a wet mill together with additional chalk and water as required, before discharge to the absorption agent basin.

Description

The invention relates to a method for recycling red sludge from a mine water treatment plant.

For the disposal of the mine water treatment Falling red mud is a significant expense for Ab settling basin, transport and landfill as well as landfill areas conducive.

It is to avoid such expenses and disadvantages known, the red mud in connection with binders and To use aggregates as building material (DE 195 03 142; DD-PS 244 545), whereby also considerable expenses for the transport as well as for the provision of binding and Sealants required to avoid leaching are.

The invention is based, the red mud on the task Power plant location without additional expenses and at Elimination of previous disposal costs recycle.

Surprisingly, it was found that with others Desulphurizing substances added red mud Production of a limestone suspension for desulphurization development of flue gases from a coal-fired power plant in one gas scrubber is used.

For flue gas desulfurization in a gas scrubber high costs for extraction and transportation of the limestone and a limestone sus for its preparation pension manufactured. There has therefore been no attempt at it missing, these expenses for the production of an absorber reducing agent suspension.

So it is known to decarbonize the steam Power station water sludge and the wet Ash removal from the sludge directly as an absorbent to be used (DE 35 04 775, DD 213 358). Likewise, be knows that when pre-cleaning water with iron salt  Wastes created as an absorption medium tel for flue gas desulfurization (DE 43 19 461 DD 289 932). However, these procedures are only on reversible when such water treatment in a power plant technologies are carried out.

Furthermore, for the manufacture of the absorbent pension a significant amount of water as well as expenses needed for its preparation.

The invention is explained in more detail using an exemplary embodiment tert. The drawing shows the system diagram for the recycling company treatment of the red mud to desulfurize the flue gases Coal-fired power plant in the scrubber.

The pit water supply 1 is integrated into the water treatment plant 2 of the coal-fired power plant. The water treatment plant 2 is connected on the one hand to the sedimentation basin 3 and on the other hand to the limestone wet mill 4 . The discharge of the limestone wet mill 4 is included in the absorption medium container 5 of the scrubber 6 .

The mode of action is as follows:
The pit water 7 passes from the pit water feeder 1 for iron removal into the water treatment plant 2 . By adding lime milk 8 and, if necessary, flocculation aids, the red mud 10 is formed for recycling by the chemical mechanism of action and raw water 9 is generated for the power plant process or released into a body of water. The red mud 10 contains due to the mine water content substances and the milk of lime ingredients desulfurization active substances, such as ferric hydroxide, and water. The red mud 10 is abandoned in the limestone wet mill 4 .

At the same time limestone gravel and what water the limestone wet mill 4 is abandoned.

If, for certain reasons, the red mud 10 is not required to the extent necessary for the flue gas desulfurization, this is conveyed into the settling basin 3 and disposed of as landfill material 11 or stored for further use. By the wet grinding process, the limestone-red mud Sus pension 14 is generated and promoted in the absorbent container 5 . The suspension 15 passes into the nozzle plane of the scrubber 6 .

Due to the chemical mechanism of action, especially in the internal cycle of the gas scrubber 6 , colorless iron sulfate is formed from the red mud, which is removed with the FGD water for moistening the ash. Thus, the used red mud has no negative influence on the suspension for gypsum extraction to be removed from the circuit of the gas scrubber, so that a gypsum quality with a high degree of whiteness is produced.

It is also possible to give the red mud 10 , but then with limestone powder and optionally water, directly into the sorbent container 5 .

The following significant advantages arise from the invention:

• 1. The effort for the disposal of the red mud, eg. B. due to the power plant.
• 2. The effort for the provision of landfill areas and their operation is eliminated.
• 3. The effort to avoid leaching from the Landfill bodies or buildings are no longer required.
• 4. The effort required to provide the limestone significantly reduced
• 5. The expenses for the water to be provided significantly reduced or eliminated.
• 6. The amount of wastewater is reduced.

Reference list

1

Mine water supply

2nd

Wastewater treatment plant

3rd

Sedimentation tanks

4th

Limestone wet mill

5

Absorbent container

6

Gas scrubber

7

Mine water

8th

Water treatment agent

9

Raw water

10th

Red mud

11

Landfill

12th

Limestone gravel

13

water

14

Limestone-red mud suspension

15

suspension

Claims (3)

1. A process for the recovery of red mud from a mine water treatment system, characterized in that the red mud with other desulfurizing substances is used to produce a limestone suspension for the desulfurization of flue gases from a coal-fired power plant in a gas scrubber. 2. The method according to claim 1, characterized in that the red mud with limestone flour and, if necessary, water placed in an absorbent container and mixed becomes. 3. The method according to claim 1, characterized in that the red mud of a limestone wet mill with an addition grinding limestone gravel and, if necessary, water given and conveyed into an absorbent container becomes.