Abstract: A method of removing silicon from a waste hydrochloric acid pickling solution is disclosed which comprises stirring the waste solution long enough to form a sludge having a particle size such that the sludge can be separated by a conventional means such as filtration through a filter of at least 0.1 .mu.m in pore diameter, centrifugation or sedimentation. The stirring period can be greatly reduced by adding to the waste pickling solution sludge recovered from an aged waste hydrochloric acid pickling solution or a carbonaceous material such as carbon black having hydrophilic groups on the surface. The sludge is also useful as a filter medium in filtration of the waste pickling solution to remove silicon. The present method can decrease the silicon content to 0.01% or less in terms of converted SiO.sub.2 /Fe.sub.2 O.sub.3 weight ratio.

Abstract: A process for producing cold-bonded or non-fired iron ore which introduced as a charge into a blast furnace. The iron ore, which contains 10 to 70% of particles having a diameter ranging from 1 to 10 mm, is molded into a block, preferably by a pressure-molding method, a shock-molding method or a packing-molding method with vibrations. The block is then cured or hardened. This hardened block is crushed to have a predetermined shape. An additive such as CaO, Al.sub.2 O.sub.3, or MgO may be added to the iron ore to adjust the basicity as a whole to 0.8 to 2.0. Moreover, the molding step is conducted so that the product may have a void volume equal to or less than 25%.