NHD developed the large agitator for 300,000t/a, pioneering the localization of the equipment in China. Meanwhile, NHD set a new record of application of high power, heavy load, extra long agitator in the industry.

NHD invested great on research of new material for agitator. Besides standard material, such as 304、304L、316L、317L 、904L etc, NHD also developed dozens of new material for various conditions of temperatures, concentration of acid or alkali, which could give best protection for high corrosion-and-wear resistance.

For example: HD-5# alloy is a type of high chrome-nickel stainless with some other element, therefore this alloy is characterized with not only high corrosion resistance but also high strength and abrasive resistance. FS-1 alloy has high abrasive resistance in either diluted or concentrated sulfuric acid, but in condition of hydrochloric acid>5%, HD-5# has a better corrosion resistance. If we feed steam into 98% sulfuric acid or in condition 93% sulfuric acid, the corrosion system will turn to diluted acid system and the amount of hydrochloric acid increased. We recommend use HD-5# alloy in above-mentioned medium. If steam were not input to 98% sulfuric acid and hydrochloric acid is less than<5%, FS-1 also can be used.

New developed HD-5# alloy has high strength, machining property, and good corrosion resistance for sulfuric acid, hydrochloric acid, nitric acid+ hydrochloric acid, concentrated sulfuric acid+ hydrochloric acid, therefore HD-5# is suitable as the material of the agitator for 98%H2SO4 S-based NPK and it would be valuable for practice application and promotion.