Study On The Synthesis Of Hydroxypropyl Carboxymethyl Potato Starch And Its Application In The Iron Powder Pellet Binder

This study used potato starch as raw materials to take chemical modified composite research, hydroxypropylization first, then carboxymethylization, and optimized the reaction conditions, got a hydroxypropyl carboxymethyl compound modified potato starch, the product viscosity aqueous solution (1%) of 5791 mpa·s, hydroxypropyl molecular substitution degree of 0.423. At the same time, used this type of composite modified starch in the iron powder pellets production and developed a new type of inorganic and organic composite binder, greatly reducing the traditional pellet binder in the dosage of bentonite. The pellets made by less harmful impurities, high compressive strength and good metallurgical performance, gave birth to the ball without drying, dry curing which was energy conservation and environmental protection technology and had good economic efficiency and social benefits.(1) The potato starch with hydroxypropyl, got the potato hydroxypropyl starch, used hydroxypropyl molecular substitution degree as the index to study the starch milk concentration, dosage of anhydrous sodium sulfate, sodium hydroxide dosage, the dosage of epoxy propane, reaction time and reaction temperature on the effects of substitution degree, through the orthogonal experiment, after verification, got the best technological conditions as follows:reaction temperature 50℃, reaction time 12 hours, starch milk concentration 30%, mass fraction 6% sodium sulfate, sodium hydroxide mass fraction 1.2%, epoxy propane mass fraction 12%, the potato in the substitution degree of hydroxypropyl starch molecules to 0.423.(2) The hydroxypropyl potato starch to carboxymethylate compound degeneration, preparation of the potato hydroxypropyl carboxymethyl compound modified starch, used the viscosity (1% aqueous solution) of compound modified starch as the indicator to study the sodium hydroxide dosage, dosage of chloroacetic acid, etherification reaction time, and etherification temperature influences of on the viscosity of product, through the single factor experiment, after verification, got the best technological conditions as follows:potato hydroxypropyl starch (raw material):alkali dosage:chloroacetic acid=1:0.8:1.2, alkaline time 60 min, etherification time 120 min, etherification temperature 70℃, the hydroxypropyl carboxymethyl potato starch viscosity of 5791 mpa·s.(3) Using the hydroxypropyl carboxymethyl potato starch F, the distribution of technical development of new organic-inorganic compound iron powder pellet binder, by iron powder pellets cold-press molding experiments, to have the ball down and finished product ball strength and compressive strength for temperature as indicators, developed a consists of bentonite, F starch, polyacrylamide, calcium carbonate and magnesium oxide to constitute a new type of binder, a typical formula is:iron powder 100 g, bentonite1.0 g, F starch 0.8 g, polyacrylamide 0.2 g, magnesium oxide0.3 g, calcium carbonate 0.3 g, water 6%. The finished ball Strength of 1012 N/one, compressive temperature greater than 800℃, the pellet drying curing time 4 days (in Lanzhou).