Abstract: A process is provided for making thermoplastic-composites from recycled thermoplastics (polyolefins) together with phosphogypsum waste by-product from the phosphate fertilizer wet process or, in an equally preferred embodiment with fluorogypsum waste by-product from fluorine production wet process to produce lumber profiles. The process involves (a) admixing phosphogypsum (calcium sulfate) and/or fluorogypsum (calcium fluoride) waste byproduct and/or Flue Gas Desulfurization (FGD) gypsum and/or crude gypsum and/or calcined gypsum with thermoplastics and a functionalized compound with or without coupling agents to produce a filled thermoplastic-composite composition, and (b) melt processing the composition to produce a filled thermoplastic-composite article.