Can industrial salts used for boiler water treatment be used for hot compresses?

Can industrial salts used for boiler water treatment be used for hot compresses? There is no problem in heating them up and then wrapping them in gauze for use as hot compresses; some industrial salts are toxic, but the toxicity is low. Industrial salt refers to crude salt, which includes lake salt, well salt, and sea salt. Among these, sea salt has a relatively higher industrial value due to the various elements dissolved in seawater, whereas its edible value is lower. Industrial salt has a wide range of uses and is one of the most fundamental raw materials in the chemical industry. Hydrochloric acid, caustic soda, soda ash, ammonium chloride, chlorine, and other major products of the basic chemical industry are primarily produced using industrial salt as raw material. "Industrial salt “usually* specifically refers to nitrites. Long-term consumption of nitrites by the human body also increases the risk of cancer; industrial salt must not be consumed.