RU2296779C1 - Method of processing polyether production - Google Patents

Abstract

FIELD: waste disposal.

SUBSTANCE: invention is dealing with processing of petrochemical production wastes and, more specifically, with utilization of sludges formed in production of polyethers. A method is provided residing in that sludge is treated with extractant followed by separation into liquid and solid phases. Invention is characterized by using water or aqueous solution of potassium phosphates as extractant. In the latter case, solid phase is composed of bentonite and liquid one emulsion of a polyether on aqueous potassium phosphate solution. Liquid phase is separated in separator into polyether and aqueous phase. The former is dried and filtered and the latter subjected to crystallization and subsequent drying of potassium phosphates.

EFFECT: increased recovery of polyethers and utilized previously rejected waste.

1 dwg

Description

The invention relates to the processing of industrial wastes of petrochemical industries and is intended for the disposal of sludge generated in the production of polyethers.

This refers to the waste from the production of polyethers formed during the anionic polymerization of ethylene or propylene oxides, or their joint block copolymerization. In the process of obtaining the target products, they need to be purified from an anionic catalyst - potassium hydroxide, which is neutralized by phosphoric acid, resulting in a mixture of potassium phosphates. To improve the crystallization and precipitation of these salts, bentonite is used. The latter is squeezed out on press filters and taken to a sludge dump. The composition of the sludge is approximately the following,%:

Bentonite 15-20 Potassium phosphate mixture 25-35 Polyester 45-60.

In Russia, these wastes are generated at the Polyester Plant of OAO Nizhnekamskneftekhim in the production of laprols.

A known method of processing sludge, which consists in processing sludge with an extractant methylene chloride, followed by separation into liquid and solid phases. The liquid phase is separated into a simple polyester - the target product and methylene chloride, which is returned to the stage of processing sludge with an extractant (RU 2225762 C1, 2004.03.20). The disadvantage is the use of toxic and volatile methylene chloride as an extractant. The solid phase, consisting of bentonite and potassium phosphates, is not further separated and is used as mineral fertilizer. This fertilizer is not suitable for all soils, but a high content of inert bentonite and residual polyester reduces the quality of the fertilizer and increases transportation costs.

The basis of the invention is the task of creating a method for the disposal of waste products of the production of polyethers, devoid of the above disadvantages, and which ensures the complete separation of the solid phase into commercial products: polyether, bentonite and potassium phosphate. The specified technical result is achieved by the fact that in the known method of processing solid waste or sludge in which by extraction and subsequent separation into a liquid and a solid phase, water or an aqueous solution of potassium phosphates is used as an extractant, and potassium phosphate and a simple polyester are isolated from the liquid phase product.

Thanks to the use of water or an aqueous solution of potassium phosphate as an extractant, the conversion of potassium phosphates to a solution is achieved; after separation of the liquid phase, pure bentonite is obtained - a commercial product. Bentonite can be used in the main production of polyethers, or for other purposes.

The liquid phase, which is an emulsion of a polyether in a solution of potassium phosphate, is divided into a simple polyester - the target product and an aqueous solution of potassium phosphate. After cooling the solution, potassium phosphate crystallizes, is separated from the mother liquor, dried and packaged for shipment to consumers. The mother liquor enters the stage of processing the sludge with an extractant.

Thanks to the introduction of water or an aqueous solution of potassium phosphate as an extractant into the known method, it is possible to achieve complete separation of the sludge into commercial products: polyether - the target product, potassium phosphate and bentonite.

A method of processing waste products for the production of polyethers, which consists in loading water or an aqueous solution of potassium phosphates into a extractor apparatus equipped with a mixing device for viscous media and a heating system and heating to a temperature of 80-90 ° C. The sludge is loaded into the apparatus-extractor and heated to a temperature of 93 ± 3 ° C with stirring. Maintain at this temperature for 15-20 minutes. At the end of the shutter, the centrifuge is turned on and, after reaching the operating mode, the mass is transferred from the extractor apparatus with compressed air so that all the bentonite remains in the centrifuge. As soon as the emulsion of the polyester in the phosphate solution begins to enter the centrate receiver, turn on the pump located downstream of the centrifuge receiver and transfer the emulsion to the separator. After filling the centrifuge drum with bentonite, it is stopped. Crude bentonite is discharged from the centrifuge and sent for washing.

The polyether emulsion in the salt solution (the centrate obtained in the previous step) is sent to the separators, where the emulsion is divided into two layers at a temperature of 85 ± 5 ° С. The top layer is a simple polyester containing water up to 4%, with a small amount of mechanical impurities (bentonite fibers). The bottom layer is a solution of potassium phosphates in water. As the centrate is fed from the separator through the overflow, polyether is selected and sent for drying. The phosphate solution through the bottom drain is sent to the mold.

The polyether taken from the separator is sent to the evaporator. Mixing and vacuum are turned on and mass heating begins. Upon reaching a temperature of 110 ° C give an exposure of 1 hour in a vacuum of 0.2 at. Upon reaching a moisture content of not more than 0.1%, the drying is stopped, the vacuum is released and sent to the filtration. Filter under pressure of 3-6 at. until a transparent product is obtained according to the standard and sent to the collection.

A hot solution of a mixture of potassium hydro- and dihydrogen phosphates is sent to the crystallizer and, with the stirrer working, is cooled to a temperature of 15-20 ° C. The resulting pulp with a membrane pump or compressed air is sent to a suction filter and squeezed out with vacuum through a filtrate collector. The precipitate of the phosphate mixture from the filter is sent for drying.

Wet potassium phosphate from the previous operation is evenly scattered with a layer of 3-4 cm on pallets of a shelf dryer and dried at a temperature of 95 ± 5 ° C to a moisture content of not more than 9%. When this result is achieved, the dryer is unloaded, the phosphate is allowed to cool to a temperature not exceeding 50 ° C and packaged in plastic or paper bags.

Raw bentonite is washed twice with water, heated to a temperature of 60-70 ° C, for 15-20 minutes and squeezed with compressed air onto a suction filter. After pressing, wet bentonite is dried in a shelf dryer and packaged similarly to potassium phosphate.

The advantage of the invention is that the sludge is completely divided into commercial products: polyester - the target product, potassium phosphate and bentonite. In this case, toxic substances and substances polluting the environment are not used.

Claims (1)

A method of processing wastes from the production of polyethers, which consists in treating sludge with an extractant, followed by separation into liquid and solid phases, characterized in that water or an aqueous solution of potassium phosphates are used as extractant; the resulting solid phase is bentonite; the resulting liquid phase - an emulsion of a simple polyester in an aqueous solution of potassium phosphates is separated in a separator into a simple polyester, followed by drying and filtration of the polyester, and a solution of potassium phosphates, followed by crystallization and drying of phosphates.