In addition to some advantages of ordinary needle punched filter felt, polypropylene needle punched filter felt cloth bag is generally used in the field of liquid-solid separation with flue gas temperature below 100 ℃ and high acid and alkalinity because polypropylene fiber has better acid and alkali resistance and lower softening point than polyester fiber. Polypropylene needle punched filter felt bag is mainly used in the field of liquid-solid separation in metallurgy, mining, petroleum, chemical industry, chemical fiber, medicine, food and other industries.