CA2120658A1

CA2120658A1 - Process for producing of sorption agents based on cellulose fibers, fragmented wooden material and clay minerals

Info

Publication number: CA2120658A1
Application number: CA002120658A
Authority: CA
Inventors: Reinhard Hahn; Otto Haubensak
Original assignee: Sued Chemie AG
Current assignee: Sued Chemie AG
Priority date: 1993-04-07
Filing date: 1994-04-06
Publication date: 1994-10-08
Also published as: ATE180417T1; EP0619140A3; DE59408297D1; JPH07817A; EP0619140B1; DE4311488A1; EP0619140A2

Abstract

ABSTRACT
A process for production of sorbents based on cellulose fibers, fragmented wooden material, and clay minerals, for uptake of liquids, is described. The sorbent is characterized in that:
(a) a finely divided, cellulose-containing material with an average fiber length of 0.4 to 3 mm and a residual moisture content of 5-15 wt. % and/or (b) a fragmented wooden material with an average fiber length of 0.05 to 2.0 mm, and a residual moisture content of 10 to 20 wt. %, and (c) a smectitic clay mineral in finely divided form with an average particle size of 0.1 to 1.0 mm, a residual moisture content of 5 to 15 wt. %, and a smectite content of at least 50 wt. %
is homogeneously mixed (d) the mixture is compacted, and (e) the compacted mixture is fragmented.
Moreover, the invention concerns a sorbent that can be obtained by this process.

Description

21206~8 T~ANSLATION FROM GERMAN

PATENT AITORNEYS ~ :
R. SPLANEMANN, B. REl'IZNER. K. BARONEI~Y

S~d-Chemie AG 9 March 1994 Lenbachplatz 6 :
80333 MumchOur File: 4465-X-16.409 PATENT APPLICATION ~ ~ ~
Process for Producdon of Sorp~ion Agents Based on Cellulose Fibers, ~ ~;
Pragmented Wooden Marerial and Clay Minerals '; .
DESCR~PllON

Thc iDven~on concerns a p~cess for p~duc~on of sorption agcnts based on cellulose fibe~s, ~agmented wood~ ma~iaL and clay mincrals for uptake of liquids. These so~ption agcnts arc suitablc for uptalcc of any givcn liquids; howevcr, ~cy are par~cularly suitable as littcr ~ ---for pets, on which account the following remarks shall pcrtain tO this area of application.

Thc ~ing of pets in a largely u~cd environment increasingly depends on d~e use of Iitter. T~s has the fmlcoon of taking up the liquids e~crcted by the animals and inhibiting or preventing the dcvelopment of an odor as much as possible. Morcover, it should r xnow moisn~re f~m the scmisolid, moist animal excsesnent and exc~dons and thcreby prcvent the :~
dwelo~nent of odor. Furthcrmore, good littcr has the property of taking up the excreted or 21206~8 removed liq uds by forming a compact clump, which can be removed in simple and economical fashion. Thus, an optimal litter has high absorbency.

The products to be found on the market are organic substances, such as straw, sawdust, wood shavings, ba~ porous plastic beads, shredded paper, cellulose fibers, ag~icultural wastes, polyacrylates, etc.; these are all used or in mixtures with inorganic materials [as pnnted]. The disadvantage of the organie litters is the often inadequate clumping, or their consisteney, as wcll as thcir tcndeney to baeterial dceomposition, espeeially in eonjunetion with moisture.

Sorption agents based on elays and elay minerals with a content of one mineral from the group of the smeetites are kno vn frorn DE-A-37 28 812 and DE-C-38 25 905, which are burned to aehieve a high porous volume at temperatures of more than 650C. Organ~c substances sueh as sawdust. co~, rice husks, or the like, can be added as pore-forming agcnts. Howev, these porc fmng agents when heated arc burned out and no longer remain in the prod~ The material resulting after the bu~ning no longer has the capaeity of swelling.

A so~pdon agcnt, pardeularly a litter for pcts, based on smeetitie elay minerals capable of swclling, whieh ean additionally contain sand or cellulose-contaLning materials like wood se~aps or ehips and f~ncntcd papcr, is known from US-A-5 000 115. No info~mation is givcn as to thc par~elc ~izc or moisturc eontcnt of thcsc addidvcs. Furthcnnorc, the eomponcnts arc mixed together dry, without eompaetion.

A mcthod for produetion of pct litter is known f~om US-A-4 341 180, aeeording to wkieh wa~-eontaimng wastc paper is brought up to a watcr eontent of around 32~10%, extruded, forrncd into pcL~, and dned. Thc wastc papcr ean eontain around 1~50% of the usual papcr fillcrs, sueh as kaolin. However~ thesc fillers are not capable of swelling. -~

A litter a~d a process for its p~duction are known *om DE-A~ 101 243, according to which cellulose, cellulose denvates, and/or cellulose-containing mate~ials of agric~lltural or industrial origin, such as ~'wowie," sic!~ wastc wood, such as ["wo wic," sic!] sawdust, with a paTdcle -sizc of up to 1 mm, arc mixed with wdghdng agcnts and thickcning agcnts, like bentonite, in 212~6~8 , the presence of water, the available water is separated, and ~e remaining residue is fragmented to a particle size above 1 mm. The weighting agent is added in such an amount that the buIk density of the litter after drying is approximately above ~00 kg/m3. A dry cornpacting of the staning mixture is not described.
, Furthermore, a litter based on cellulose-containing material as the wet substance and a capillary-behaving fine-grained material, such as bentonite, is known f.~m DE-A-3 816 225, which offers. certain advantages over the organic litters, such as higher bulk density.
Prcferably, recovered paper stock as the wet substance, with a moisture content of 50 60%, and pumicc with a moisture content of dO%, are mixed and then dried.

Thc usc of the cellulose-containing matenal as the wet substance necessitates a cosdy drying ;
of the litter.

Furthermore, a litter based on cellulose in wadding form, and ground-up clay, is known from -~
DE-A 4 028 933.1~ thc manufacture of this litter, waste paper is processed into a wadding ~<
type stn~e and mi~ced with ground clay ~6ao~inite and quartz) on high pressure-producing ~-pmscs. According to "Ullmann's Encyclopcdia of Technica'l Chemis~y," 4th Edition, Volumc 23, pagc 312ff, kaolinite is a twin-layercd mmeral, while quartz or pumice is not Ncn a laycscd mincraL Thcrefore, these matesials cannot be used to produce a litte; that is capable of fom~i~g clumps when wcttcd.
'' As opposcd to thc abovc-presented state of the are, it has now been found that the properties ~-of sarbcnts, paT~cularly littcrs, can be substantially improved if the components are used in -~
par~ally dried fo~m and, in paTticular, if smectitic triple-layer minerals are used as the mine~
ions, along with finely diivided cellulose-containing materials. ~ ~
~'.

Thus, the invention concerns a process for production of sorbents based on cellulose fibers, ~ed wooden material, and clay minesals for uptake o~ liquids, being ch~actenzed in that ~'~'. ' ' ' "

212~ 8 (a) a finely divided. cellulose-containing material with an average fiber length of 0.~3.0 mm and a residual moisture content of ~1~ wt.%, andlor (b) a finely divided wooder~ material with an average fiber length of 0.0~2.0 mm and a residual moisture content of ~20 wn%, and (c) a smectitic clay mineral in finely divided form with an average particle size of 0.1-1.0 mm, a residual moisture content of 5-15 wt.%, and a smectite content of at least 50%
arc homogcneously mLl~ed (d) thc mLxturc is compactcd. and (c) tbe thus-compactcd mixturc is fragmcnted.

The smcctitic clay mincrals used are capable of forming clumps, thanks to their ability to swcll with aqucous liquids. On account of this clumping, the fraction of the litter that is wcttcd with liquid can bc scpara~ely rcmovcd, thus economizing on the litter. The special stracture of t'ne smectitic clay minc~ls is also rcsponsible for the ability to adsorb annoying ~`
smclls prcduced by thc animal excrctions and exc~emcnt. Furthcrmorc, the smectic clay minerals can bc easily disposed of, without harming thc cnvironment. ~ ~

The flncly divided, cellulose-containing matedal used is prcferably finely ground cellulose ~ ~ ;
and/or a soco~y-fibcr-containing ccllulosc matcrial, and thc fragrnentcd woodcn matcrial is prcfesably fincly ground wood flour and/or f~agmcnted wood sha~ings. Prefeably, the mixn~rc is compactct, briquct~ or prcss-granulatcd tunng stage (d).

Prcferab~, a prcssing force of 20 200 kN/cm is used, espccially 40 100 ~N/cm, and the staning rm~c is prcfcrab}y canduc~d bctwecn prcssing rolls (briqucfflng rolls or prcss-granulatingrolls).

P~ferably, the i~am;ng lmm~e in prcviously dricd fo~m w th a water content of ~19 w~% is c~ed, brique~ or press-granulated In dlis way, one can entirely avoid a drying of ~e finished product, i.e., a major economic advantage is asso~ated with the production proccss x~ ,,,i ;,, ,,.,,,, .. "" ," ",, , ~ , ,~ ~,~, ,, ,~; ,,, ,, ,""

212Q6.~8 of the inven~ion. The costly explosion protection measures requi~d when drying cellulose-containing material can also be dispensed with.

Thanks to the use of smectitic clay materials capable of swelling, it is su~pnsingly possible for mixtures of primarily finely divided cellulose-containing materials and/or fragmented wooden materials (which do not in themselves f~m clumps with liquid) with small fractdons of swelling smecddc clay minerals to also form clumps when wetted with liquid.

Prcfcrably, thc wdght rcladonships between finely divided cellulose-conta~s~ing matenal and/or fragmcnted wooden matenal, on the one hand, and smecdtic clay mineral, on the other, lic between 0.5:9.5 and 6.5:3.5, especially between 1:9 and 5:5. An excellent clumping is achieved when these weight reladonships are used.

Prcferably, one starts with a Ca aod/or Na-smecdte with a water absorptivity (adjusted to the dried smectite with xsidual moisture content of 6 wt.%) of at least 100%, preferably 120-350%, esp~ially 120-300%, and a smectite content of 60-80 wn%. Besides the smectite, thc sméctitic clay mincral can contain othcr clay mincrals, such as kaolinite and mica, feld~par and quar~
.
According to anothcr prefcrrcd cmbodiment, thc star~ng mixnlrc with a water content of S-20% i~ compac~d, briquctted, or press-granulated in a prcss~ng assembly ~e.g., a roll compactor of the Bepex company or the Koppern company).

A furthcr a~mization of the litter's propcrties can bc achieved in that the mixture is adjusted to a ~ain sizc of around 0.1-10 mm, preferably 1-5 mm, especially with a component of 20-35 w~% of fracdon 1-2 mm and a component of 80~5 w~% of the fracdon 2~5 mm, and thc fincs produccd by the fragrncnt~non are sifted off and rcturned tO the mixing a~rangement. ~ ; -Preferably, one begins w~th a fine-fibcr and/or a secondary fiber-containing cellulose raw materiaL espe~ally a material conta~niing ccllulose fibers with an average fiber length of 0.~3 mm, preferably 0.8-1.5 mm, and a water content of ~15 wt.%. However, one can also .; - ,,.",. .. .. -,;. . . -: ., , ; ,, ,.. ,, ~ .. ,- - ... . ,,. .. -.. -............ .

2120~8 , start with a finely ground wood flour andJor a fragmented raw material containing wood fibers, especially a fiber-containing material with an average par~icle leng~ of 0.~2 mm, preferably 0.1-1.0 mm, and a water contem of ~20%.

Other mixtures of finely divided cellulose-containing material and fragmented wooden material can be used.

Moreover, the invention concerns a sorbent that can be obtained by the above-descnbed method and that is characterized by a residual moisture content of around ~19, preferably 1~15 wt.%, and a water uptake capacity of mo~e than 100 wt.%, preferably more than 120 wt % (referred to the mixture dried to a residual moisture content of 6 wt.%).

The invented sorbent forms clumps when wetted with aqueous liquids.

The invented sorbent usually has a bulk density of 300 900 g/l, preferably 400 70~ g/l.

Moreover, the invented sorbent can be cut with familiar sorbents. ID addition, the sorbent can contain whioe pigments, disinfectants, and/or animal acceptance agents.

Moreover, the inveDtion concesns the use of tho above-indica~cd sorbent as packing material, ab~orbent of liquids, such as body fluids, oil, liquid chemicals, and as pet litter, especially for cats The p~pcr~cs of the invented sorbent are gene~ally dc~mined ag follows:

1. Wa~er Absorp~ivir"

Using a modification of method 17-A of the WEST~IGHOUSE company, ~0 g of the granular sorbent are placed in a weigbed conical wire screen witb a diameter of 7 cm and a beight of 7.6 cm.

,, ,.~.. ,~",.", ",,: , " . ", ~ "r,i .. " , " ~ ,~ ", -", , , ,: , ~

2120~8 The filled screen is then suspended in a water-filled beaker so that the material is completely covered with water. After an uptake time of 20 minutes, the screen is hung for an additional 20 minutes in an empty beaker and allowed to drip. At the end of the drip time, the screen and its contents are again weighed. The water absorptivity (%) corresponds to the equation 100 x EJD, where E is the quantity of water taken up and D is the measured amount of granular material added.

2. Water Content A granular spccimen is dried down to constant weight in a dry~ng cabinet; the content of adsorbed water is determined from the wedght difference before and after drying. Specifically, ~ ;
1~20 g of granulate is placcd on a flat dish, wcighed to within Q01 g, and dried down to constant weight in the drying cabinet at 100C (at least two hours). After this, the specimen is cooled to room temperature in a desiccator and then weighed. The water content is computed as follows:

Weigh in - Wdgh out Water content (%) = ~ ---- x 100 Weigh in In similar maMcr, the watcr contcnt of the finely di~/ided ccllulosc~containing material or the f~agmentcd wood~ materhl can be dctcrmined.

3. WaterBreakthrough Test Water is suppL;ed from a 50 ml burette to the granular sorbent loosely placed on a glass dish (diameter 140 mm, height 75 mm, fill height 50 mm), evencd out without compaction, and the depch of penetration is obse~ed. The outlet of the burette is placed at a heigh~ of 3~ cm in che middle of the pile of mau~ial, after which 60 ml of t~ water is allowed to drain out wi~in 55 60 seconds. After waiting for 3 minutes, the bottom of the dish is checked for water. The presence of water is detected by a discoloradon of the granular material at the bottom of he dish. The evaluation is donc as follows:

212~6~

- No discoloraion at the bottom of the dish: test passed;
- Discoloration evident at the bottom of the dish: test faile~ `

4. BullcDensi.y A 500 ml graduated cylinder is first weighed empty. After this, a powder funnel with an opetung of around 15 cm and an outlet opening of around 3 cm is placed on it and filled with thc granulated sorbcnt within around 5 seconds. After this, the powder funnel is removed from the graduated cylinder in such a way thu the granulate located inside forms a projecting conc. This is smoothed off with a broad spatula along the cut edge of the graduated cylinder.
Thc filled cylinder is frced of clinging grains or dust on the outside and again weighed. The bullc density is cotnputed as follows:

Bullc density (g~l) = 2 x na wdght W500 ml}
~ . ~
Thc invention is explained by thc following examples:

Exomp~e I (Companson) Ground~up scrap paper with an avcragc fiber length of 0.8-1.2 mm (around 10 wt.% water) is compac~d and b~lccn up in a compactor of the Hutt company a, 200 - 50 P) at a presshg pre~surc of around 40 l~N/cm and thc grcun fraction of 1-5 mm is siftcd off.

l~c brcalcthrough tcst is failed; thc moistcned material docs not form clumps.

E~ran~le 2 (Companson) 2 kg of a mixmrc consisting of 25 wt.~o ground-up scrap paper with an average fibcr length of 0.~1.2 mm (c~und 10 w~% wate~) and 75 wt% of ground-up, quartz-containing, namral crudc kaolin with a watcr contcnt of around 1~15 wt.%, arc compacted, brokcn up, and siftcd as dcscribcd in Example 1. Thc littcr roughly corrcsponds to thc litter of DE-A-4 028 933.

212~6.~8 ::: :
The break~rough test is failed; the moistened material does not form clumps.

Exom~le 3 As a modification of the procedure described under Example 2, instead of crude kaolin one uses 75 wt.% of groland-up natural Ca-bentonite (montmorillonite content approximately 60%) with a water content of around 10-15 wt.%.

The breakthrough test is passed; the moistened material forms clumps that can be completely rcmoved in compact form.

Water absorptivi~: 510 wt%
Watercontent 10.6 wt.%
Bul~c density: 650 gJl l~xample 4 (Con~ on) ~ :

Appro7umately 2 kg of grou~d-up wood flour (hardwood) with an average particle size of 0.1-0.5 mm (approximately 10 wt.% water) arc compactcd in a compactor of the Hutt company ¢. 200 - 50 P) with a prcssing forcc of around 40 IcN/cm.

The breakhrough test is failed; the moistened material does not form clumps.
"

E~Dnple 5 (Con~arison) ;

As a modification of thc procedmc described in Esample 4, a fragmented ground-up wooden m~t~al (hardwood) with an average pamcle length of 0.5-2.0 mm (around lO w~% water) is used and b~ken up after being compacted and sifted off to the grain fra~ion of 1-5 mm ~he brealahrough test is failed; thc moistened material does not folm clumps.

....

212D6.~8 Ex~le 6 (Cornpanson) Around 2 kg of a mixmre consisting of 30 wt.% ground-up wood flour with an average particle length of 0.1-0.5 mm (around 10 WL% water) and 70 wt.% ground-up nanlral quartz-containing crude kaolin with a water content of around 10-15 wt.% are compacted, broken up, and sifted as descnbed in Example 1.

The breakthrough test is failed; the moistened material does not form clumps.

Ex~mple 7 As a modification of the procedure described under Example 6, instead of crude kaolin one uses ground-up natural Ca-bentonite (montmorillonite content approximately 60%) with a water content of ar~und 1~15 w~%. The mix relations and wooden materials used are su~Tized in Table 1.

l'he breakthrough test ~s passed; the moistened matcrial forms clumps that can be fully removed in compact form.

Tabb 1.--Mi~ of wood~ mat~ial with smeaitc and d ploper~es thereof h~x~ , WIY= Bull~ Wa~r 8~eahhrough Bcochwood (96) Bcnto~c (~o) Contcnt Den~iq ~dnq Test 20 ) 80 13.7 630 142 30 ) 70 135 550 173 Pa~scd 40 )1 60 13.4 500 210 Passed 50 ) 50 14.0 420 245 Passed S~uce wood (~o) Bemoni~e (%) ~
20 1) 80 14.1 737 154 Passed 20 2) 80 14.8 796 151 Passed l) Pa~bclc s~zc 0~1.0 mm 2) Par~clc i~zc 01-0.5 mm Mi~mres ~f glain ~actions 30~O 1-2 mm and ~0% 2-5 mm 212~6;~8 Example 8 As a modification of the procedure described in Example 7, a mixture consisting of 15 w~%
ground-up wood flour (around 10 w~% water), 15 wt.% ground-up scrap paper (around 10 w~% water), and 70 wt.% ground-up natural Ca-bentonite (montmoriIlonite content a~und 60%) with a water content of around 1~15 wt.% is compacted. The material is compacted, broken up, and sifted as describcd in Example 1.

The brealctl~ugh test is passed; the moistened material forms clumps that can be removed in compact fo~

Water absorptivity: 440 wt.%
:
Water content: 12.3 wt.%
Bulk density: 670 g/l Il

Claims

1. Process for production of sorbents based on cellulose fibers, fragmented wooden material, and clay minerals, for uptake of liquids, characterized in that (a) a finely divided, cellulose-containing material with an average fiber length of 0.4-3.0 mm and a residual moisture content of 5-15 wt.%, and/or (b) a finely divided wooden material with an average fiber length of 0.05-2.0 mm and a residual moisture content of 10-20 wt.%, and (c) a smectitic clay mineral in finely divided form with an average particle size of 0.1-1.0 mm, a residual moisture content of 5-15 wt.%, and a smectite content of at least 50% are homogeneously mixed (d) the mixture is compacted, and (e) the thus compacted mixture is fragmented.

2. Method per Claim 1, characterized in that the finely divided cellulose-containing material used is a finely ground cellulose and/or a secondary fiber-containing cellulose material, and the fragmented wooden material is a finely ground wood flour and/or fragmented wood shavings.

3. Method per Claim 1 or 2, characterized h that the mixture is compacted, briquetted, or press-granulated in step (d).

4. A Method per Claim 3, characterized in that a pressing force of 20-200 kN/cm preferably 40-100 kN/cm, is used.

5. Method per one of Claims 1-4, characterized in that the starting mixture is conducted between pressing rolls, such as briquetting rolls or press-granulating rolls.

6. Process per one of Claims 1-5, characterized in that the starting mixture with a water content of 10-19 wt.% is compacted, briquetted, or press-granulated.

7. Process according to one of Claims 1-6, characterized in that one starts with a Ca and/or Na-smectite with a water absorptivity (referred to the dried smectite with a residual moisture content of 6 wt.%) of at least 100 or so, preferably 120-350%,especially 120-300%, and a smectite content of 60-80 wt.%.

8. Process according to one of Claims 1-7, characterized in that a cellulose fiber-containing material with an average fiber length of 0.4-3 mm and a water content of 5-15 wt.% and/or a finely ground wood flour and/or a fragmented wood pulp-containing material with an average particle size of 0.1-2.0 mm and a water content of 10-15 wt.% is used.

9. Process according to one of Claims 1-8, characterized in that the weight relations between finely divided cellulose-containing material and/or fragmented wooden material, on the one hand, and smectitic clay mineral, on the other, are adjusted to 0.5:9.5 to 6.5:3.5, particularly 1:9 to 5:5.

10. Process according to one of Claims 1-9, characterized in that the mixture is adjusted to a grain size of approximately 0.1-10 mm, preferably 1-5 mm, especially with a component of 20-35 wt.% of the fraction 1-2 mm and a component of 80-65 wt.% of the fraction 2-5 mm and the fines produced by the fragmentation are sifted off and returned to the mixing arrangement.

11. Sorbent that can be obtained by the method of Claims 1-10 and that is characterized by a residual moisture content of around 6-19, preferably around 10-15 wt.%, and a water absorptivity of more than 100%, preferably more than 120% (referred to the mixture dried to a residual moisture content of 6 wt.%)

12. Sorbent per Claim 11, characterized in that it forms clumps when wetted with aqueous liquids.

13 13. Sorbent per Claim 11 or 12, characterized by a bulk density of 300-900 g/l, preferably 400-700 g/l.

14. Sorbent per one of Claims 11-13, characterized in that it is cut with familiar sorbents and also contains white pigments, disinfectants, and/or animal acceptance agents.

15. Use of the sorbent per one of Claims 11-14 as packing material, absorbent for liquids, such as body fluids, oil, liquid chemicals, as well as litter for pets, particularly cats.