RU2244685C1 - Method of cleaning oil-polluted soils, grounds, and oil-slimes - Google Patents

Abstract

FIELD: oil pollution elimination.

SUBSTANCE: method comprises washing of ground (soil, oil-slime) with washing liquid, regeneration of liquid by way of phase separation to remove organic phase and to return water phase into cleaning cycle. Prior to be washed, ground is separated into floating substance and precipitated ground and each separated component is then washed separately. Floating substance is subjected to jet treatment on vibrosieve, during which operation washed substance is separated from pollutants by washing liquid. Precipitated ground is washed in three steps: first-step washing is carried out by precipitation in washing liquid stream, material is then subjected to jet washing on inclined screw conveyer with stirring, and finally material is subjected to jet treatment on vibrosieve with simultaneous separation of material from pollutants. Washing liquid is regenerated by gravity settling.

EFFECT: improved quality of closed-cycle washing.

2 cl

Description

The invention relates to the protection of the environment, namely the reclamation of oil-contaminated lands, the disposal of soil, soil, oil sludge.

A known method of cleaning oil sludges and soils (RF patent No. 2111665, C 02 F 11/00), according to which oil sludge and oil-contaminated soil are removed from the sludge collector, treated with a demulsifier, filtered from large particles larger than 10 mm, treated and heated with water vapor to a temperature 40-50 ° C. Then the sludge is sedimented for 15-20 minutes, during which time the sludge is divided into four phases: oil product, water, water-sludge suspension, oiled mechanical impurities, while the removed mechanical impurities are washed with a hydrocarbon solvent and water vapor.

The specified method is used in the integrated processing of liquid sludge. The main purpose of this method is to obtain productive oil.

A known method of cleaning soil and oil sludge in the center for washing the soil and oil sludge company "ERSO" (Flyer "Offer company EKPO for the supply of technological systems for environmental restoration"), including sifting the soil or sludge from large debris on vibrating screens, jet washing of large particles and sand with washing liquid with simultaneous separation of fine-grained sludge on an inclined screw conveyor when moving the material, a three-stage washing of fine-grained sludge in a container with stirring combined with the separation of liquid and solid phase, the return of the washing liquid after the third stage of washing fine-grained sludge to the first stage of washing and periodic removal of the oil emulsion from the washing tank.

The known method is complex and not effective enough. The jet washing of large particles and sand on a screw conveyor does not ensure their neutralization to a sufficient degree, and the three-stage washing of fine-grained sludge, combined with the separation of liquid, requires large volumes of washing liquid and complicates the process.

The objective of the present invention is to simplify the process of cleaning oil-contaminated soils, soil and oil sludge, improving the quality of washing, ensuring the implementation of cleaning in a closed cycle while maintaining the activity of the washing solution returned to the cycle.

This is the technical result.

The technical result is achieved by the fact that in a method for cleaning oil-contaminated soils, soil or oil sludge, including washing the soil (soil, sludge) with a washing liquid, regenerating the liquid by phase separation with separation of the organic phase and returning the aqueous phase to the cleaning cycle, according to the invention, before washing the soil ( soil, sludge) is divided into a floating mass and sedimented soil (soil, sludge), and then each separated fraction is washed, while the floating mass is washed by blasting on a vibrating screen with one temporary separation of the washed mass from the contaminated washing liquid, washing the precipitated soil (soil, sludge) is carried out in three stages, at the first stage, washing is carried out by sedimentation in the flow of washing liquid with a volume ratio of deposited soil (soil, sludge) and liquid not less than 1: 1 , at the second stage, the material is jet-washed on an inclined screw conveyor when moving the material; at the third stage, the washing is carried out by vibro-jet blasting with simultaneous separation of the washed soil (soil, sludge) o t of contaminated washing liquid, the washing liquid is regenerated by gravity sludge, oil-contaminated soils, soils or oil sludge are cleaned in a closed cycle, and before the washing liquid is supplied to the cleaning cycle, it is additionally cleaned of mechanical impurities, using 0.3- 3.0% aqueous detergent solution with a temperature of 40-95 ° C, forming an unstable emulsion with hydrocarbon contaminants.

The method is as follows.

Contaminated soil, soil containing plant and other residues, as well as solid sludge and / or solid-liquid pulp-like sludge collected during the cleaning of the earth's surface during emergency oil spills are taken as an object of washing. Before starting the cleaning process, the prepared washing liquid is preferably heated to a temperature of 60 ° C. As a washing liquid, a 0.3-3.0% aqueous solution of a detergent forming an unstable emulsion with hydrocarbon contaminants is used, for example, the UBON, UBON-D technical agent and other detergents containing nonionic surfactants with additives.

Contaminated soil and / or soil or sludge (hereinafter referred to as soil) are fed to the loading grate of the hopper filled with an aqueous solution of detergent, and with the help of the operator are washed away with a solution stream from the washing unit, while lumps and clots of the soil are destroyed with the simultaneous washing and mechanical action of the washing liquid for oil pollution. Blurred soil, passing through the grid cells, enters the hopper. When soil enters the hopper, not sinking mass and oil float, and heavy soil settles to the bottom of the hopper. Soil separation is carried out in a dynamic mode.

The washing process of the deposited soil is carried out in several stages. At the first stage, the soil is washed in the hopper with a stream of hot detergent solution, where the optimal effect of the detergent on oil pollution is carried out. It was experimentally established that the volume ratio of the deposited soil and the washing solution should be at least 1: 1. At the second stage, jet washing is carried out on an inclined screw conveyor when moving soil from the hopper to the vibrating screen through an integrated washing unit. The third stage of jet washing the soil is carried out on a vibrating screen with simultaneous separation of the soil from the contaminated solution. The washed soil is discharged into containers, and the contaminated washing solution is supplied for regeneration. Three-stage washing of the deposited soil (soil, sludge) provides a high degree of neutralization and environmental safety of the soil.

Simultaneously with the washing of the deposited soil, the floating mass and oil are removed from the hopper. The floating mass is fed to a vibrating screen, where the mass is jet-cleaned from oil pollution with simultaneous separation from the contaminated washing solution. Washed and environmentally friendly plant and other residues are dumped into containers, and the contaminated solution is fed for regeneration. The blasting of the floating mass of plant and other residues on a vibrating screen provides a continuous flushing of oil from the surface.

Contaminated washing liquid is dynamically regenerated by gravity sludge with constant heating using steam registers installed in a settling tank. The use of an aqueous solution of a detergent forming an unstable emulsion as a washing liquid provides rapid phase separation with a low residual concentration of carbon compounds in the aqueous phase. The regenerated aqueous solution is returned to the cleaning cycle and fed to the jet washing plants. In this case, before the washing liquid is supplied to the cycle, the solution is additionally purified from mechanical impurities by means of a hydrocyclone. During the cleaning process, the activity of the washing solution is controlled and, if necessary, its concentration is adjusted to the required values.

Depending on the degree of soil contamination (soil, sludge), the pressure regime in jet washing plants is regulated, while the rate of erosion of contaminated soil, the ratio of the volume of deposited soil and the washing solution, and mechanical washing of oil pollution from the surface of the material on vibrating screens are ensured. In addition, when washing heavily contaminated soil, the time for blasting of the deposited soil is increased when moving on an inclined tubular screw conveyor by changing the speed mode.

At the end of the working shift, the aqueous solution is pumped out of the settling tank into the auxiliary pit, the sediment is discharged using a screw conveyor, the accumulated oil is pumped out using a vacuum pump, sent for further processing or used as fuel. In the pit, the residual concentration of detergent is deposited by the flocculant, water is used for further work. Environmentally friendly soil, plant and other residues are collected and transported to collection points or undergo further processing.

The method is illustrated by examples.

Example 1

They cleaned the soil contaminated with crude oil, cut from the surface of the wetland, containing soil, plant debris. The oil content is about 20%. An aqueous solution containing 0.3 wt.% Detergent with a temperature of 60 ° C was used as a washing liquid. Washing was carried out according to the above technology. Provided a volume ratio of contaminated precipitated soil: washing solution 1: 1. At the end of the cleaning process, the oil content in the washed soil did not exceed 0.8%.

Example 2

Purified sludge containing soil, soil, plant debris contaminated with crude oil. The oil content is about 35%. As a washing liquid used 0.6% aqueous solution of detergent, the temperature of the solution 65 ° C. Cleaning was carried out according to the above technology. Provided a volume ratio of contaminated precipitated soil: washing solution - 1: 2. At the end of the cleaning process, the oil content in the washed soil did not exceed 1.0%.

Example 3

The solid-liquid pulp-like sludge, taken from the sludge collector, containing ground plant residues, solids, and water was cleaned. The oil content is about 50%. As a washing solution, a 2% aqueous solution of detergent was used; the solution temperature was 75 ° C. Cleaning was carried out according to the above technology. Provided a volume ratio of contaminated soil: washing solution 1: 3. At the end of the cleaning process, the oil content in the washed soil did not exceed 1.1%.

Thus, the method allows to neutralize contaminated soil, soil, plant and other residues and to ensure the quality of washing while simplifying the cleaning process in comparison with the analogue.

Claims (2)

1. A method of cleaning oil-contaminated soils, soil or oil sludge, including washing the soil (soil, sludge) with a washing liquid, regenerating the liquid by phase separation with separation of the organic phase and returning the aqueous phase to the cleaning cycle, characterized in that before washing the soil (soil, sludge) ) are divided into a floating mass and deposited soil (soil, sludge), and then each separated fraction is washed, while the floating mass is washed by blasting on a vibrating screen with simultaneous separation of the washed mass from lignite washing liquid, washing the deposited soil (soil, sludge) is carried out in three stages, at the first stage washing is carried out by sedimentation in the flow of washing liquid with a volume ratio of deposited soil (soil, sludge) and liquid not less than 1: 1, at the second stage carry out ground washing on an inclined screw conveyor when moving the material; at the third stage, washing is carried out by vibration processing on a vibrating screen with simultaneous separation of the washed soil (soil, sludge) from contaminated washing liquid, my regeneration liquid is carried out by gravitational sludge, cleaning is carried out in a closed cycle, and before supplying the washing liquid to the cleaning cycle, it is additionally cleaned of mechanical impurities. 2. The method according to claim 1, characterized in that as a washing liquid using 0.3-3.0% aqueous solution of detergent with a temperature of 40-95 ° C, forming an unstable emulsion with hydrocarbon contaminants.