CHEMICAL REGENERATION OF THE WASTE OILS USING THIOCARBAMIDE

To regain the operational properties of the waste oils are applied different methods of purification and regeneration which are based on the physical, physical and chemical processes and remove the "aging" and contaminating products. However, the most spread are methods of chemical regeneration when the concentrated sulfuric acid or alkali is used. At the same time applying these methods cause another problem of hazardous waste utilization.

Nowadays, among the numerous of the waste oil regeneration methods without any hazardous waste, the attention should be paid to the methods with the complexing compounds, as urea. However, the disadvantage is a use of aqueous solution of reagents what may cause some oils operational properties renovation and the oil emulsion formation, precipitations, filters clogging of the internal combustion engines lubricating system.

The possibility of the waste oil chemical regeneration with crystalline thiocarbamide usage was studied. To identify the process control factors, the influence of the reagent quantity, process duration and nature of the waste oils on the operational properties of the regenerated oils were observed.

There were two samples of waste oils got from the maintenance services: industrial and transformer. The waste oils samples characteristics were: the high values of the acid number (AN) (1,9 to 3,1 mg КОН/g), water content (0,06 to 0,5%), unsatisfying values of the kinematic viscosity 50 and 100°С and viscosity indexes.

The process of waste oil chemical regeneration by thiocarbamide was studied using the three-chamber reactor with a mechanical stirring, a thermometer, and a doser for the reagent supply.

On the basis of the experiments results it`s been found out that with increasing of thiocarbamide in the process of waste oils chemical regeneration the value of AN decreases and the values of kinematic viscosity and waste oils index viscosity increases. It`s been elucidated that the lowest AN value can be reached using 12% wt of thiocarbamide, but kinetic viscosity value 50 and 100° С and viscosity index have insignificant changes while increasing the amount of reagent from 7 to 12 % wt. Observing the process of waste oils regeneration with thiocarbamide showed that with increasing of the duration the AN value decreases and the viscosity boosts. The optimal duration of the interaction process of the waste oils with urea was 60 minutes. Studying the influence of the waste oils nature on the chemical regeneration process has been established that the renovation of some operational properties develops differently for all used samples. It happens because of waste oils chemical composition, area and conditions of the use. The waste oils operational properties do not restore after thiocarbamide chemical regeneration according to the DSTU values. That`s why the process of waste oils chemical regeneration with thiocarbamide can be used only as an intermediary of the combined process of the waste oil regeneration.