Abstract: A novel process for treating and recovering valuable metals and other components from pickling acid residue (PAR) has been developed. The metals and other components are recovered by neutralizing the pickling acid residue using a magnesium compound or a mixture of magnesium compounds, and separating components of the resulting mixture (metals and sulfates) into products that can be reused, such as magnesium sulfate, nickel sulfate, iron and chromium phosphate, or various metal hydroxides or oxides.

Abstract: A novel process for treating and recovering valuable metals and other components from pickling acid residue (PAR) has been developed. The metals and other components are recovered by neutralizing the pickling acid residue using a magnesium compound or a mixture of magnesium compounds, and separating components of the resulting mixture (metals and sulfates) into products that can be reused, such as magnesium sulfate, nickel sulfate, iron and chromium phosphate, or various metal hydroxides or oxides.

Abstract: A retaining wall system is comprised of a plurality of courses of side-by-side parallelogram front face patterns, each parallelogram front face pattern formed by first and second rows of a plurality of quadrilateral face patterns. The first and second rows of the plurality of quadrilateral face patterns have the same width and collectively define a height of the parallelogram front face pattern, with each of the parallelogram front face patterns having the same height. The quadrilateral face patterns in the first row have a width different than that of the quadrilateral face patterns in the second row. Each parallelogram front face pattern in a first course overlies two parallelogram front face patterns in an immediately adjacent course. The combination of off-sets of the quadrilateral face patterns in each parallelogram front face pattern and overlapping of parallelogram face patterns in adjacent courses creates a retaining wall having a non-uniform appearance of a natural stone wall.