Preparation method of modified bentonite particle retention aid for papermaking

The invention relates to a preparation method of a modified bentonite particle retention aid for papermaking, comprising the following steps of: mechanically pulverizing mined natural bentonite into particles below 200 meshes, then dispersing the pulverized bentonite in water, and washing and sieving to remove impurities; adding an acid solution into bentonite suspension for reacting and then separating to remove the precipitated impurities; extruding and dehydrating the separated bentonite suspension, repeatedly washing and extruding until the pH value is 3-6.5; and finally, diluting and dispersing bentonite subjected to acidization with water, adding sodium salt for reacting and then diluting the bentonite suspension until the mass concentration is 0.01-5% to obtain the modified bentonite particle retention aid. In the invention, the adopted two-step modification method can be used for favorably removing the impurities in the bentonite so as to improve the content of the active ingredients in the bentonite, and in addition, the extrusion and dehydration treatment can be carried out before drying so as to improve drying efficiency and reduce production cost. The method benefits the improvement of the quality of the bentonite particle retention aid and use effect of the same in papermaking.