The Research Of Defoaming Combined Mechanical Stirring With Depressure

Foam is widespread in daily life and industrial production,generally appearing in the industrial production process.There would be some useful or useless foam in industrial process,but if the bubble is not treated timely and effectively.It will make negative effects.After the coal preparation in flotation process,the strong stability of a three-phase bubble did not burst in pulp,causing a decline in pulp transport capacity,affecting the filtering effect of coal recovery and filter,increasing the concentration of circulating water,causing environmental pollution hazards.Currently,anti-foaming methods in Coal Preparation are not good,and some of the anti-foaming methods are based on the actual situation of each coal preparation plant.It can not be widely promoted and applied.Therefore,without effects to the subsequent step of the process,designing a efficient and broad applicability anti-foaming way is important for the development of technology and the hazards of coal flotation in pulp.This essay aims at combining defoaming device with simulation inflatable flotation device,based on research group on the basis of different industries defoaming technology research and summary,trigging the negative anti-foaming technology into anti-foaming process,with defoaming mechanism of negative pressure and combined effects of mechanical force,designed a new vacuum defoam mechane.We designed the laboratory test system of defoaming,the preliminary exploratory defoaming test and changed the structure of the anti-foaming equipment,researched the defoamer antifoaming mechanism.The exploratory tests showed that:Compared with normal pressure,the higher the growth rate of the foam layer in the vacuum.At a relatively low degree of vacuum(degree of vacuum?1.5kpa)experiment,with the increasing degree of vacuum defoaming increases,the defoaming efficiency has been improved.In the micro-pressure(vacuum degree>-0.2kpa)compared with atmospheric pressure defoaming,it has lower defoaming,lower energy consumption and anti-foaming effect is ideal.Subsequent to adjust the defoamer central structure,the test results showed that:Vacuum defoaming saving nearly 6min than the same volume of foam under atmospheric pressure,anti-foaming effect is more remarkable in the circumstance of double effect of the impeller,and with the increasing degree of vacuum and defoaming,the advantages are more obvious.In the study of anti-foaming mechanism,analysised the balance between the flow defoamer in pulp and gas defoaming,we deduced the efficiency formula under pressure pumping conditions.Researched the action of negative pressure and the influence of mechanical force affected the bubbles,analysised the foam decay mechanism of the bubble expands in the negative pressure,the surface area of the foam increased,and the film of bubble began to decrease the mechanical strength,the surface tension of the bubble is increased but the change in the amplitude start decreasing,causing the elastic modulus E decreases.At the same time,it will accelerate the process of draining the surface water,increased mutual merger between the bubbles,the bubbles become bigger and eventually lead to rupture,under the mechanical force,foam system skeleton quickly disappeared.