Waste treatment of fluoroborate solutions

An integrated process for removing waste drag-out containing dissolved fluoroborates from work pieces that have been subjected to in line treatment in a fluoroborate bath and for pollution free disposal of process effluents which comprises

• maintaining a first rinse zone containing an acidic solution, a second rinse zone containing a neutralizing solution, and a third rinse zone containing water;
• continuously moving the work pieces from the fluoroborate bath into and through each of the first, second and third rinse zones, whereby fluoroborate waste drag-out is substantially removed from surfaces of the work pieces into the acidic solution of the first rinse zone, and drag-out from the first rinse zone is substantially removed from said surfaces into the neutralizing solution of the second rinse zone, and drag-out from the second rinse zone is removed from the surfaces into the water of the third rinse zone;
• continuously passing the acidic solution containing the fluoroborate waste drag-out from the first rinse zone to a first treatment zone maintained at an elevated temperature of at least 130.degree. F and at a pH of about 4 or less adding calcium ions to the first treatment zone to liberate fluoride values from the fluoroborate drag-out, wherein the total amount of calcium ions in the first treatment zone is sufficient to provide at least 0.25 times the potential molar fluoride value of the fluoroborate drag-out;
• recirculating the acidic solution containing liberated fluoride values to the first rinse zone for further removal of fluoroborate waste drag-out;
• continuously passing from the second rinse zone the neutralizing solution containing the drag-out from the first rinse zone including liberated fluoride values to a second treatment zone;
• maintaining sufficient alkaline conditions in said second treatment zone to precipitate calcium fluoride;
• recirculating the neutralization solution depleted in fluoride values to the second rinse zone for further removal of drag-out from the first rinse zone;
• recovering precipitated calcium fluoride from the second treatment zone, and withdrawing spent rinse water from the third rinse zone.