Method for producing hydrotalcite-like compound, hydrotalcite-like compound, complex oxide, anion adsorbent, and solid base catalyst

A hydrotalcite-like compound and a silicon compound are synthesized at low cost by effectively utilizing iron and steel slag that is a waste resource. Specifically disclosed is a method for producing a hydrotalcite-like compound, which comprises: a step wherein an acid such as hydrochloric acid is added to iron and steel slag so as to melt the iron and steel slag, thereby obtaining a solution; a step wherein a gel that contains silica is produced in the thus-obtained solution; a step wherein the solution containing the gel is separated into the gel and a liquid; and a step wherein an alkali is added into the thus-obtained liquid, thereby producing a hydrotalcite-like compound.