214
T H E J O U R N A L OF I N D U S T R I A L A N D EIVGINEERING C H E M I S T R Y
of old newspapers i s sufficient, b u t if used in greater proportion, t h e effect is slightly better. T h e effect of t h e suspended material appears t o be a double one: i t removes t h e oils of t h e binder, a n d i t a t t r a c t s t h e carbon away from t h e pulp a n d holds i t . Upon subsequent washing with water t h e pulp may be retained b y a gauze or screen, a n d t h e minute particles of suspended material which hold t h e finely dispersed carbon and some oil are washed away. T h e best temperature for t h e procedure is about 5 0 ’ C. T h e less t h e concentration of t h e pulp, while t h e ratio of chemicals t o old papers remains constant, t h e greater is t h e de-inking effect. For practical reasons, a pulp is rarely less t h a n 2 per cent. T h e alkali a n d suspended material should be placed in t h e pulping machine with t h e water a n d heated t o s o o C. before t h e addition of t h e old newspapers. T h e paper must be perfectly pulped, which m a y b e accomplished by various machines within a period of less t h a n one hour. T h e pulp must be thoroughly washed, requiring about one-fourth less water t h a n f o r bookstock. T h e resulting product is free from carbon a n d oil, a n d has only a faint yellow coloration. I t is ready for immediate use for making newspaper. T h e product obtained described in t h e last paragraph may be bleached by treatment with a solution of sulfur dioxide, which gives a product as white, if not whiter, t h a n t h e original unprinted paper. I n practice t h e bleaching has been accomplished in ~j min. b y t h e use of 20 lbs. of sulfur dioxide i n cord water, per ton of old papers. The United States Civil Service Commission has announced examinations for metallurgists a t $3000 to $3600 per year and assistant metallurgists a t $2000 to $3000 per year, to fill vacancies in the Bureau of Mines a t Pittsburgh, Pa., and elsewhere. Candidates will be rated on (1) education, training and experience, and (2) writings (to be filed with the application). Applications will be received until the hour of closing business on April 5 , 1921. An examination has also been announced for laboratory assistants to fill vacanciFs in the Bureau of Standards a t $1200 to $1380 per year. Competitors will be rated in the following optional subjects : advanced general physics, electrical engineering, civil and mechanical engineering, chemical engineering, paper technology, textile technology, ceramics, physical metallurgy, physics, and chemistry, and will be rated on (1) elementary physics, chemistry, and mathematics, (2) optional subjects, and (3) general education, experience, and fitness. Applications will be received until further notice. Examinations will also be given for laboratory assistant, junior grade, a t $1000, and senior aid a t $900, to fill vacancies in the Bureau of Standards. Competitors will be rated on ( I ) physics and chemistry, (2) mathematics, (3) mechanical drawing, and (4) general education and experience. Applications will be received until further notice. Examinations have also been announced for microallalysts to fill vacancies in the Bureau of Chemistry a t $1200 to $1800 a year. Competitors will be rated on (1) education, training, and experience, and (2) thesis, reports or publications to be filed with application. Applications must be filed with the Civil Service Commission, Washington, D. C., by the hour of closing business on March 15, 1921.
VoI. 13, NQ.3
REGENERATING BOOKSTOCK’ By Charles Baskerville and C. M. Joyce COLLEGE OF THE CITY
OF
NEW YORK,N E W YORK,N. Y.
T h e enormously increasing o u t p u t of magazines a n d t r a d e journals, a n d a somewhat less large, b u t growing, production of books have created greater demands for book a n d magazine paper, which herein is collectively designated “bookstock.” With t h e exception of t h e cheaper grades of magazines, sulfite, soda, or sulfate pulp constitutes t h e larger portion of t h e cellulosic basis of t h e paper used. Some mechanical pulp is used in t h e cheap grades of magazines and light reading matter. Bookstock carries more or less filler a n d sizing, very variable in character a n d quantity. Other cellulose fibers, cott o n , linen rags, esparto, etc., enter i n t o book paper, which may become a p a r t of a n assemblage of waste paper. Inks of various compositions a n d colors have been used on t h e collected waste. T h e economies involved in “Recovery a n d R e manufacture of Waste Paper”2 are interestingly brought o u t by Strachan, although he does not deal with a n important phase of t h e subject particularly of concern in t h e United States. T h e reworking of waste paper for t h e manufacture of box-board, roofing, etc., has developed t o a considerable industry in t h e United States, a n d t h e demand for such promises increasing growth. A marked differential for boxboard, of immaterial color, a n d sheets for printing mill undoubtedly always obtain, b u t ‘whether i t will economically carry t h e burden of regeneration is a question debated, b u t as yet unsettled, for a general policy in national conservation by some of t h e largest paper producers in this country. However, a t this particular time a n d for some years t o come, t h e regeneration of bookstock means conservation a n d profit. Various processes, either mechanical or chemical i n nature, or both, have been proposed for special papers (photographic, waxed, etc.) a n d some of t h e m are in practical use t o a limited extent. M a n y of t h e processes, when tried on a commercial scale mrith t h e general run of waste paper, fail t o give t h e superior pulp desired for book paper. T h e failure is due in some instances t o t h e fact t h a t in t h e mechanical pulping of t h e stock t h e ink pigments are driven i n t o t h e fibers, necessitating drastic t r e a t m e n t for separation, which shortens a n d weakens t h e fibers, as well as incurring (uneconomical) losses in washing t h e pulp. T o secure t h e best results mechanically, t h e fibers require t o be loosened a n d t h e n drawn, not torn, from t h e matte. Devices have been constructed t o meet t h e mechanical difficulty, b u t they involve time a n d power factors with mounting costs of operation. S o r m a l l y bookstock is a cellulosic fiber which has had severe chemical treatment. On t h e principle t h a t t h e binder of printing ink was a saponifiable oil, caustic solutions have been and are used t o “lift” t h e 1 Presented before the Division of Industrial and Engineering Chernistry a t the 60th Meeting of the American Chemical Society, Chicago,. 111, September 6 t o IO, 1920. 2 James Strachan, 191 8.
Mar., 1921
T N E J O U R X A L OF I N D U S 2 ' R I . A L A N D E N G I N E E R I N G C H E M I S T R Y
pigment from t h e fiber, which, i f ground wood pulp be absent, and if t h e concentration of t h e caustic Rc regulated, and if t h e temperature be not too high, serves t o remove R large proportion of carbon ink. Too great ii concentration may bring about some mercerization. More weakly alkaline solutions, f o r example, sodium silicatc, sodium phosphate, boras, soap, etc., also lift t h e ink in part a n d d o little damage t o tile fiber. Hovixwer, t h e detergent effect calls for scouring or rubbing, which so embeds t h e carbon in t h e fiber as t o make it almost impossible t o sep:irate t h e two. Certain solvcnts. as kerosene or gasoline. tend t o loosen t h e iiik by dissolving t h e binder. This may be combined with irn alkaline solution, for example, a borax or a soap solution. During agitation t h e suds or skim, which forms on t h e surface of t h e water and entangles t h e carbon particles, may IJCwnshed :%Nay. Rosin is extensively used as a filler and binder foit h e fibers of t h e paper, which have n "surface." As mentioned, some oi t h e cheaper magazine papers contain wood pulp, which retains natural gums and resins. They servo in part as hinders for t h e ink pigments. Pinc oil is one of t h e normal solvents for rosin, gums, a n d resins. so its addition t o t h e old printed matter helps materiirlly t
