US942207A - Process of treating the spent liquor of paper-mills. - Google Patents

Description

I. KITSEE. PROCESS OF TREATING THE SPENT LIQUOR OF PAPER MILLS. A'n'moumx rnmn FEB. 20,1902. nnsswsn APR. 8, 1900.

942,207. Pat ented Dec. 7, i909.

WITNESSES r v INVENTOR amawz Z ISIDOB KITSEE, OF PHILADELPHIA, PENNSYLVANIA.-

PROCESS OF TREATING THE SPENT LIQUOR OF PAPER-MILLS.

Specification of Letters Patent.

Patented Dec. 7, 1909.

Application filed l'ebrueryzo, 1908, Serial No. 144,347. Renewed April 8, 1909. Serial No. 488,788.

To all whom it may concern:

Be it known that I IsmoR Krrsnn, of the city and county of Ihiladelphia, State of Pennsylvania, have invented a certain new and useful Im rovement in the Process of Treatin the pent Liquor of Paper or Pulp ills, of which the following is a specific'atio My invention relates to an improvement in the process of treating the spent li uor of paper or pulp mills, so as to be ena led to extract from said spent liquor the caustic or alkali, and also to extract from said liquor the resinous and allied substances, and

it is the further, aim ofmy invention to prepare the reclaimed caustic or alkall in a manner so as toimpart to the same the causticity necessary for its reemployment.

In the rocess of producing aper from wooden r, the wood is eit er cut or ground into pieces of convenient size and then boiled in a caustic or alkaline solution. Through this process, all the intercellulose substance, such as'resinous material, etc., is extracted from the wood and dissolved in the caustic or alkaline solution. To reclaim the caustic ,or alkali, the solution is boiled down to a syrupy consistency and then fired, whereby the resinous matter becomes entirely carbonized. The residue is again dis-- solved in water, and then filtered. In this process, the resinous material is not only lost, but it requires a great amount of fuel to'carbonize or burn up the same, so as to be* enabled to reclaim the alkaline or caustic matter. In this process, a great amount of.

hydrated alkali has always to be added to kee up the causticity, as it is technically cal ed. It is one of the aims of my invention, to

' vent its use.

other by a porous septum. Each of these compartments is provided with an electrode, the electrode of the negative compartment may consist of copper, iron or lead or other suitable conductor, but the electrode of the positive compartment should consist if possible of a material not injuriously affected by the electrolyzing action of the current, such for instance as platinum, but as the price of this metal may be a bar to employ-' mg the same, lead, graphite, or carbon may be'used instead. I am well aware that the lead will slowly oxidize and may even impart to the liquid in the positive compartment a reddish tint, but as the liquid contents of this compartment will not be used for any other purpose than for separating the resinous maternal, this action of the current will not be detrimental enou h to pre- The' connection 0% the two electrodes as to the charging current is as .usual. The negative electrode or the elec-.

trode contained in the negative compartment is connected to the negative pole of the char ing circuit, and the electrode contained in t e positive compartment is connected to the ositive pole of the charging circuit. In a s ort time, the test will show that the contents of the negative compartment has acquired a stronger alkaline re-action than the contents of the positive compartment. In my experiments, I have generally added a slight amount of sulfuric acid in the positive com artment, so as to hasten the separation of t 1e resinous matter from its liquid contents. After the current has passed through the electrolytic aparatus for a suflicient length of time, it was ound that all the alkali hadaccumulated in the negative compartment and all the acid in the positive compartment, but the liquid in the ne ative compartment remained surcharget? with various matters and it needed a second process to clarify this liquid. In my later experiments, .I therefore used the following arrangement :I placed the spent liquoronly in the positive compartment of the. electrolytic apparatus containing two compartments, using in the second or negative compartment ,plain water, and as this water has to be made more conductlng and as it was necessary to add to the resulting caustic liquid of the former e rperiments more caustic, I added to the plam water a 'chlorid of sodium, known in commerce, as

positive compartment becomes aciduous and the resinous material thereby coagulates and separates out of the liquid. Third,t he liquor in the negative compartment remains clear and unadulterated. Fourth,the necessary degree of causticity is imparted to the liquid. But, it is obvious, that to regain for the negative compartment the degree of causticity required will take agreater length of time than if part of the spent liquor would have been therein. Andlt is a matter-to be decided by the person in charge of the plant, if the first method should be employed or if the second method is preferred 1n his particular case. In both cases, if

the negative compartment consists at the beginning of pure! water with an addition of salt, or consists'gin the be inning of spent liquor with anaddition 0 salt, the result- 'ant product is:, in the negative compartment, an alkali, and in the positive comthat it will, in its gaseous state, leave the tents of the ed, I would suggest that t partment, the resinous material mostl floating on top, because of its fine subdiv1-. sion, and the chlorin or chlorinated liquid. In such cases, where the spent liquor has only traces of resinous material, and where the causticity should be of a greater degree, the chlorin enerated in the positive compartment wfil be in such superabundance compartment and it is therefore advisable, for the purpose of protecting the atmosphere, as well as for the purpose of saving the chlorin as, to close the positive compartment an to provide the same with an outlet pipe, preferably passin into a tank of water. This water, as we as the conositive compartment, after being cleared rom the resmous and allied matter, may then be used for the purpose of bleaching as is well known by persons versed in the art. a For such mills where my process is adapte usual high temperature should not be employed in the treatment of the. wood fiber with the caustic liquor, as the lower the temperature adopted, the more perfect will be the state of the reclaimed resinous and other matter, and the better quality of the product more than repays for the greater length of time required.

In the accompanying drawing, in which Figure 1 illustrates in a partial section and partial diagram one arrangement in which an electrolytic a paratus is used to recover simultaneously e caustic and resinous substances, and in which Fig. 2 is a plan view of the material designed tor-strain the 1iquid,A is the tank containing the spent liquor B, this tank is provided with the pi e G connected 'with the interposition of t e valve D to the pipe E, havmg the branch- %ipes E and It, provided with the valves 1 and D respectively.

The electrolytic ap aratus consists of the containing vessel G, liere divided into two compartments B and B each filled with the necessa liquid. These compartments are divided y the porous (partition C the compartment B is provi ed with the electrode H, and the compartment B is provided with the electrode I. These two compartments are also provided with the removable rece tacles g and g respectively. These remova ble receptacles preferably consist of a material, such as a very closely woven wire gauze or textile, so as to be able to collect the mechanical impurities contained in the liquid to be electrolyzed, and also so as to be able to collect the resinous material and to have the drained-out liquids as pure and clarified as possible; for this reason I have also provided the guards J, J,

woven wire gauze or textile. The compart-' ment B is provided with the outlet pipe F containing the valve D and the compartment B is provided with the outlet pipe F containing the valve D. It is obvious that the arrangement of this electrolytic ap aratus may differ and I have illustrat a form which I have found well adaptedfor the urpose.

aving now described my invention, what I claim asnew'and desire to secure by Letters Patent is 1. The process of treatin s ent liquor from pa er or pulp mills w ic comprises placing t e spent liquor in the positive compartment of an electrolytic apparatus, in placing a solution of salt in the negative compartment of said apparatus, in sending currents of electricity through said compartments whereby the solution in the ne ative compartment becomes alkaline and t e intercellulose and resinous material is retained in the positive compartment.

2. The process of treatin s ent liquor from paper or pulp mills w icli comprises subjecting said spent liquor to the action of an electric current in the positive compartment of an electrolytic ap aratus, the negative compartment of said tainin a second conducting fluld.

3. e process of recovering the caustic apparatus con- 942,207 H n a and resinous matter Of the spenfi liquor from ne'sses, this seventeenth day of February,

paper 01" pulp 1mills, 'vLhich cldmpnses m1ak- A. D. 1903. V

m said spent iquort e ano yte in an'e ec- I tri c apparatus and sending currents of elec- ISIDOR KITSEE' 5 tricity through said apparatus.- Witnesses:

. In testimony whereof, I hereby sign my I EDITH R. STILLEY,

name in the presence of two subscribing wit- 1 CHAs. KRESSENBUCH.

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