During selective precipitation of light rare earth elements from concentrated sulphuric acid monazite sulphate solutions, substantial amount of thorium was co-precipitated. This study deals with leaching most of this co-precipitated thorium under various conditions of pH, solution/solid ratio, agitation time, and leaching temperature. Also, preparation of high-grade thorium concentrate suitable for further purification steps was involved from the produced leach liquors. This conducted through some thorium selective precipitation methods such as precipitation at controlled pH and hydrolysis. The optimized conditions reveal that leach water of pH 1.0, the ratio to light rare earth double sulphate solid precipitate of 20.0 and agitation for 6.0 h at 80oC dissolve more than 79% of Th with only minimum of light rare earth elements as 2.8%. However, the initial prepared thorium concentrate containing about 45% Th, while the final concentrate containing more than 70% thorium which seems to be suitable to conduct further purification steps.