Study On Preparation Of Oxidized Kerosene And Application In Low-rank Coal Flotation

Coal washing is an important part of the clean and efficient use of coal.Coal flotation is an effective method to improve the quality of coal slime and reduce dust.Facing with the increasing in slime production and the ratio of difficult floating coal,the widely used non-polar hydrocarbon flotation reagents such as kerosene and diesel oil have been difficult to meet the production requirements.Therefore,the development of new flotation reagents or modification of existing flotation reagents has important practical significance.According to the shortcomings of currentl flotation agent,the kerosene is modified by catalytic oxidation and non-catalytic oxidation to increase the content of polar component.The properties of oxidized kerosene were determined by means of acid value,saponification value measurement and infrared spectrum characterization.The flotation performance of oxidized kerosene was tested by flotation experiments on two low-rank coals,namely Majialiang coal and Erdos cucurbitaceous coal.The oxidized kerosene was classified according to the type of functional group,and the flotation performance of different components was tested to determine the flotation active component in the oxidized kerosene.The oxidation of kerosene was catalyzed by using manganese naphthenate as a catalyst.Through investigation of different process conditions,it was found that oxidized kerosene with good flotation efficiency can be obtained in 5 hours of oxidation at such conditions:the catalyst feed ratio is 0.1%(calculated as metallic manganese),the oxidation temperature is 150?,and the air flow rate is 250 mL/min,and the flotation effect canot be improved obviously by prolonging the oxidation time.The oxidized kerosene produced by catalytic oxidation itself has foaming property,and it can be used as a collector with secondary octanol as foaming agent,and can also be used as a composite flotation agent alone;for the flotation application of Majialiang coal,under the same flotation index,the oxidized kerosene as a collector can save the dosage of both collector and foaming agent more than 75%,and as a compound flotation agent in a dosage of 1000 g/t,the clean coal yield reaches 77.58%,the clean coal ash content reaches 19.91%,the flotation effect is good.Three kinds of fatty acid products such as stearic acid,oleic acid and ricinoleic acid were selected as initiators on non-catalytic oxidation of kerosene,and it was found that three kinds of initiators all can significantly increase the oxidation efficiency of kerosene,and the promotion ability:ricinoleic acid>oleic acid>stearic acid.Different initiator structure have different selectivity for oxidation products,saturated bonds favor the formation of carboxylic acids,unsaturated bonds favor the formation of alcohols,aldehydes,ketones and other polar non-acid components,and when the ?-CH2 linked to the unsaturated bond is substituted by hydroxyl groups,the formation of polar non-acidic components is more favorable.In order to ensure the oxidation efficiency,the oxidation temperature should not be lower than 140?.The non-catalytic oxidation kerosene has superior flotation performance,and can perform effective flotation on Ordos Hulusu coal which cannot be floated by kerosene.The collection performance of esters in oxidized kerosene was the strongest,followed by acidic substances,and non-polar hydrocarbons were the weakest.When used as a collector,its dosage between 1000 and 2000 g/t.and the dosage of secondary octanol above 100 g/t,can always achieve a ideal flotation effect.When the requirement of the fine coal ash is high,the amount of oxidized kerosene should be controlled at about 1000 g/t,the amount of secondary octanol should be controlled at about 100 g/t.The optimum dosage of oxidized kerosene as a composite flotation agent should be controlled at about 1500?2000 g/t,reducing the dosage will reduce the yield of clean coal,while increasing the dosaget will increase the clean coal ash.When the demand for clean coal ash is high,the amount of oxidized kerosene should be controlled at 1500 g/t.