Abstract: This invention relates generally to a method for extracting lignosulfonate for the manufacture of vanillin and other specialty chemicals. Specifically, the invention relates to a method for recovering lignosulfonates from newsprint comprising the steps of:a) converting newsprint to a crumb pulp comprising of from about 20% to about 50% crumb pulp fiber solids by weight on an oven dry basis and the remainder water;b) cooking the crumb pulp in a medium comprising crumb pulp and cooking acid solution selected from the group consisting of sodium bisulfite, magnesium bisulfite, ammonium bisulfite, calcium bisulfite or mixtures thereof wherein the weight ratio of cooking acid solution to the crumb pulp fiber is from about 3 to about 6 for sufficient time and sufficient temperature and pressure for lignosulfonate removal;c) separating the crumb pulp fiber from the spent sulfite liquor; andd) recovering the lignosulfonates from the spent sulfite liquor.

Abstract: An apparatus for controlling the rate at which a defoaming agent is supplied to a processing vessel. A first sensing element senses the quantity of liquid in the vessel. A second sensing element senses the position of the upper surface of the foam. A signal processing circuit combines the outputs of the first and second sensing elements to produce a signal that is used to optimize the rate at which defoaming agent is supplied to the vessel. In this manner, the amount of defoaming agent that is used is reduced, thereby reducing the cost of operating the process.