There are several acids that are commonly used in gold recovery, including:

1. Hydrochloric acid (HCl): This acid is commonly used to clean gold jewelry and remove any tarnish or dirt that may be present on the surface of the gold. It can also be used in some gold recovery processes to dissolve base metals and other impurities that may be present in the gold-bearing material.

2. Aqua regia: This is a mixture of nitric acid (HNO3) and hydrochloric acid (HCl) in a 1:3 ratio. It is a very strong and corrosive acid that can dissolve gold and other noble metals, such as platinum and palladium. Aqua regia is often used in gold refining and recovery processes to dissolve gold and separate it from other metals or impurities.

3. Sulfuric acid (H2SO4): This acid is commonly used in the production of fertilizers, detergents, and other industrial chemicals. In gold recovery processes, sulfuric acid can be used to dissolve base metals and other impurities that may be present in the gold-bearing material.

4. Nitric acid (HNO3): This is a strong and corrosive acid that can dissolve gold and other noble metals. It is often used in gold refining and recovery processes to dissolve gold and separate it from other metals or impurities.

It's worth noting that working with acids can be dangerous, and proper safety precautions should always be taken when handling them. This includes wearing appropriate personal protective equipment, working in a well-ventilated area, and following proper handling and disposal procedures.