CS233847B1 - Method of sewage treatment from coal or ore mining degradated with iron or manganese - Google Patents

Abstract

The present invention provides a method for cleaning waste from the extraction of coal or ores containing coal dissolved iron, possibly manj gan, where he uses both iron and mangai coagulation agents to the present purification of water containing coagulable both inorganic and organic substances origin. The two waters are mixed 1:10 up to 3: 1 with alkaline lime and using flocculant auxiliary. The invention finds use in mining coal or ores.

Description

The invention relates to a process for the purification of coal or ore waste water containing dissolved iron and optionally manganese by coagulation in admixture with water contaminated with coagulable substances of both organic and inorganic origin.

From coal and some ores eliminated water containing _t The decisive released by iron or manganese and in many cases in an amount which does not permit the direct discharge of water into streams. It is usually cleaned with alkaline lime with intensive aeration to produce a large volume of sludge with a large consumption of alkalizing agent and a large excess of air. On the other hand, many waters contaminated with coagulable substances of both inorganic and organic origin are disposed of and must be disposed of before they are discharged into the stream or used for their intended use. This is usually done by coagulation by the addition of hydrolyzing salts of iron or aluminum. Especially in the case of more polluted waters, quite a considerable amount of these agents must be added to overcome the coagulation threshold of colloidal impurities in the water, which in turn leads to large waste sludge / coagulant production, which is moreover difficult to drain.

Substantial improvement can be achieved by the treatment of coal or ore waste effluents containing ionically dissolved iron or manganese by mixing with water containing coagulable substances of inorganic and organic origin, for example with water after the biological treatment stage, in a ratio of 1:10 to 3 : 1. The addition of calcium hydroxide increases the hydroxyl ion concentration to a minimum value of 10 " mol / l in the absence of divalent manganese in the waste water and to 3.10 " mol / l in the presence of divalent manganese. -20 minutes by dissolved oxygen from the air supplied to the mixture, followed by the addition of a flocculating aid such as polyacrylamide or potato

233 847 starch, or derivatives thereof, at a dose of 0.2 mg / l to 5 mg / l and the resulting sludge with impurities are allowed to separate from the mixture and the aqueous phase free of contaminants is separated from the sludge.

The advantage of the process is that the pollutants of the waste water from coal or ore extraction, i.e. ionically dissolved iron, which would otherwise have to be removed from these waters as a coagulating agent, are used as a coagulating agent in the purification of waters contaminated by coagulable substances. otherwise it was necessary to add the coagulant in the form of a salable product. This would create a double volume of sludge. A further advantage of the process is that by mixing both types of water, the natural alkalinity in the contaminated by coagulable substances is utilized to neutralize the waste water from coal or ore mining, replacing at least a portion of the alkalizing agent necessary to establish the necessary OH ions concentration . Furthermore sludge falling off from the mixture of the two types of water is preferably separable from the aqueous phase than in the separate treatment, as was common in the presence of ^{coagulation-1} koaguA centers of suspended solids from both waters.

Further explanation of the method is in the following example.

Example

Waste water from surface lignite mining and water leaving the brown coal combination waste water treatment plant in a ratio of 1 part mine water to two parts water from the biological treatment plant were fed to the through-flow mixing apparatus equipped with a turbine mixer. The average values of both waste waters are given in Table 1.

Table 1

Mining water pH 6.05 m mmol / l 1.5 Fe mg / l 225 Mn mg / l 10.1 Code mg / CO2 ₂ Nerozp. mg / l 15 Dec Water z biol. dry cleaning 7, * 3.0 0.5 0.7 19.0 32

233 847

An alkalizing agent in the form of a calcium hydroxide slurry was also added to the mixer and further air was supplied to the bottom in a ratio of 3.5-4 volumes to 1 volume of the water mixture.

The average residence time in the mixer was 25 minutes.

At the outlet of the mixer, swellable potato starch was added to the formed aqueous slurry as a flocculating aid in an amount of 2.3 mg / L and the slurry fed to a sedimentation apparatus based on a perfectly suspended sludge bed. Purified water was already leaving the sedimentation facility.

The amount of calcium hydroxide added to the mixer was controlled so that the concentration of OH ions in the purified water was adjusted to the required level. During operation, it was regulated gradually to establish three different concentrations of OH ions, corresponding to pH values: 8.7, 9.5, and 10.0.

The results of purified water at these different pH values are shown in Tab. 2:

Table 2

pH m inmol / 1 Fe mg / l Mn mg / l Qty mg / 1 0 ₂ Nerozp. mg / l 8.7 2.5 1.0 0.6 8.0 4,5 9.5 1.4 0.2 0.35 6.0 1 10.0 0.65 0.2 0.1 6.1 2.4

From the economic point of view, the most advantageous regime around pH 9.5 appears to be »

Claims (1)

SUBJECT OF THE INVENTION 233 847 Method for the purification of coal or ore waste water by coagulation, characterized in that coal or ore waste water containing ionically dissolved iron or manganese is mixed with water containing coagulable substances of inorganic and organic origin, e.g. water after the biological treatment step, 1:10 to 3: 1, adding calcium hydroxide increases the concentration of hydroxyl ions to a minimum value of 10 ° mol / l in the absence of 6 bivalent manganese in the waste water, and to 3.10 moles In the presence of divalent manganese and with stirring, the mixture is treated for 5 to 20 minutes with dissolved oxygen from the air supplied to the mixture, followed by the addition of a flocculating aid such as polyacrylamide or potato starch or derivatives thereof. from 0.2 mg / l to 5 mg / l and the resulting sludge with impurities is allowed to set aside and the aqueous phase free of contaminants The extracts are separated from the sludge.