DK171051B1

DK171051B1 - Method of producing an adsorbent made of an expanded mineral and calcium sulphate hemihydrate, and use thereof

Info

Publication number: DK171051B1
Application number: DK200188A
Authority: DK
Inventors: Heiner Hamm; Peter Hartmann; Karl-Heinz Kampner; Hans-Friedrich Kurandt
Original assignee: Knauf Westdeutsche Gips; Embsen Gipswerk
Priority date: 1987-04-24
Filing date: 1988-04-12
Publication date: 1996-05-06
Also published as: ATE76782T1; CA1312063C; DK200188D0; DK200188A

Description

i DK 171051 B1in DK 171051 B1

Opfindelsen vedrører en fremgangsmåde til fremstilling af et adsorptionsmiddel, især til dyriske afsondringer, af et opblæret mineral og kalciumsulfat-halvhydrat, ved hvilket 5 et kornet opblæret mineral (et mineral der i naturtilstand indeholder vand og ved en varmebehandling er ekspanderet til en porøs form med luftblærer) og kalciumsulfat-halvhydrat blandes til et granulat, ved hvilken kalciumsulfat-halvhydratet ved tilsætning af vand i overskud helt ændres 10 til kalciumsulfat-dihydrat, og ved hvilken frit vand fjernes ved tørring.BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a process for the preparation of an adsorbent, especially to animal secretions, of an inflated mineral and calcium sulphate semi-hydrate, in which a granular blasted mineral (a mineral containing in water in nature is expanded to a porous form with air vesicles) and calcium sulfate semi-hydrate are mixed into a granulate, in which the calcium sulfate semi-hydrate, upon addition of excess water, is completely changed to calcium sulphate dihydrate and at which free water is removed by drying.

Ved en kendt fremgangsmåde (DE-PS 30 21 377) af denne slags anbefales til adsorptionsmidlet et vægtforhold kalciumsul-15 fat:perlit på maksimalt 5:1, og blandingen sker i en rote rende granuleringstromle, hvorved der i det væsentlige fremstilles runde granulater med et perlitkorn og kalcium-sulfat-dihydratovertræk, hvorved granulatet har et vandindhold på ca. 18 vægtprocent. Den tilfredsstillende ad-20 sorptionsvirkning ved dette adsorptionsmiddel opnås ved anvendelse af forholdsvis meget perlit, som er dyrt. Ligeledes opnås tilstrækkelig hårdhed og afslidningsstyrke for det ved den kendte fremgangsmåde fremstillede adsorptionsmiddel ved tilsætning af en polyalkohol.In a known process (DE-PS 30 21 377) of this kind, a weight ratio of calcium sulphate: perlite of a maximum of 5: 1 is recommended for the adsorbent, and the mixture takes place in a rotating granulation drum, thereby producing essentially round granules with a pearl grain and calcium sulfate dihydrate coating, wherein the granulate has a water content of approx. 18% by weight. The satisfactory adsorption effect of this adsorbent is obtained by using relatively high perlite, which is expensive. Also, sufficient hardness and abrasion resistance of the adsorbent produced by the known process are obtained by the addition of a polyalcohol.

2525

Det er derfor opfindelsen opgave at skabe en fremgangsmåde af den i indledningen nævnte slags, ved hvilken der kan fremstilles et adsorptionsmiddel, hvis andel af opblæret mineral er formindsket, hvis adsorptionsvirkning på det 30 nærmeste er bibeholdt, og hvis hårdhed er forhøjet uden tilsætninger. Fremgangsmåden ifølge opfindelsen, til løsning af denne opgave, er kendetegnet ved, at kalciumsulfat-halvhydrat og opblæret mineral blandes i sådanne mængder, at der i adsorptionsmidlet foreligger et vægtforhold kal-35 ciumsulfat:opblæret mineral større en 5:1 og indtil 10:1, at blandingen sker ved, at kalciumsulfat-halvhydrat og op- DK 171051 B1 2 blæret mineral hældes sammen i en beholder, og der ved hjælp af et røreværktøj sammenrøres til en granulatblanding, at granulatblandingen efter tilsætning af vand og før tørring henligger mindst 4 minutter, og at det tørre 5 kalciumsulfat-dihydrat ved kalcinering ved 120° til 200°C i et sådant omfang ændres til kalciumsulfat-halvhydrat, at adsorptionsmidlet udviser et samlet vandindhold på 1 vægtprocent til 16 vægtprocent.It is therefore the object of the invention to provide a process of the kind mentioned in the preamble, by which an adsorbent may be prepared whose proportion of bloated mineral is diminished, the adsorption effect of which is almost retained, and whose hardness is increased without additions. The process according to the invention, for the purpose of this task, is characterized in that calcium sulfate semi-hydrate and bloated mineral are mixed in such quantities that in the adsorbent there is a weight ratio of calcium sulphate: bloated mineral greater than 5: 1 and up to 10: 1. that the mixture is effected by mixing calcium sulphate semi-hydrate and blistered mineral in a container and stirring with a stirring tool to a granulate mixture that the granulate mixture, after addition of water and before drying, is left to stand for at least 4 minutes. and that the dry 5 calcium sulfate dihydrate upon calcination at 120 ° to 200 ° C is changed to such an extent as calcium sulfate semi-hydrate that the adsorbent exhibits a total water content of 1% to 16% by weight.

10 Fremgangsmåden ifølge opfindelsen arbejder med en mindre mængde opblæret mineral og fremstiller et adsorptionsmiddel, som på den ene side udviser smådele, som er en kerne af opblæret mineral med kalciumsulfat-overtræk, og på den anden side udviser smådele, som kun er dannet af kalcium-15 sulfat. Adsorptionsmidlets smådele er i det væsentlige u-runde og udviser en overflade med åbne porer. Trods formindskelsen af mængden af opblæret mineral bevares adsorptionsmidlets samlede adsorptionsvirkning ved hjælp af den kalcinerede kalciumsulfats yderligere adsorptionsvirkning.The process of the invention works with a smaller amount of bloated mineral and produces an adsorbent which, on the one hand, exhibits small parts which are a core of bloated mineral with calcium sulfate coating, and on the other hand exhibits small parts which are formed of calcium only. Sulfate. The small parts of the adsorbent are substantially un-round and exhibit a surface with open pores. In spite of the reduction in the amount of bloated mineral, the total adsorption effect of the adsorbent is retained by the additional adsorption effect of the calcined calcium sulfate.

20 En formindskelse af det samlede vandindhold med 1 vægtprocent forøger adsorptionsvirkningen med ca. 3%. Selvom produktets hårdhed normalt går stærkt tilbage ved kalcinering af kalciumsulfat-dihydratstykker, er dette ikke tilfældet ved fremgangsmåden ifølge opfindelsen.A reduction of the total water content by 1% by weight increases the adsorption effect by approx. 3%. Although the hardness of the product is usually greatly reduced by calcining calcium sulphate dihydrate pieces, this is not the case with the method of the invention.

2525

Det fremstillede adsorptionsmiddels hårdhed er ikke mindre end granulatets hårdhed før kalcineringen og større end hårdheden for adsorptionsmidlet, der er fremstillet ved den kendte fremgangsmåde.The hardness of the adsorbed produced is not less than the hardness of the granulate prior to calcination and greater than the hardness of the adsorbent prepared by the known process.

30 Særligt formålstjenligt og fordelagtigt er det, hvis kalciumsulfat-halvhydrat og opblæret mineral sammenrøres i sådanne mængder, at der i adsorptionsmidlet foreligger et blandingsforhold kalciumsulfat:opblæret mineral på 6:1 til 35 8:1. Ved dette vægtforhold er der givet en gunstig mineral besparelse og adsorptionsmidlets vægtfylde er endnu ikke DK 171051 B1 3 særlig højt. Det kornede, opblærede mineral indeholdes ikke blot i adsorptionsmidlet på grund af sin adsorberende virkning, men også for at nedsætte adsorptionsmidlets vægtfylde indenfor visse grænser. I mange tilfælde, for eksempel ved 5 fremstilling af kattegrus, foretrækkes et forhold på 5,1:1 - 6,5:1, for eksempel 6:1.Particularly advantageous and advantageous is if calcium sulfate semi-hydrate and bloated mineral are stirred in such quantities that there is in the adsorbent a calcium sulfate: bloated mineral ratio of 6: 1 to 8: 1. At this weight ratio, a favorable mineral saving has been given and the density of the adsorbent is not yet very high. The grainy bloated mineral is not only contained in the adsorbent due to its adsorbent effect, but also to decrease the density of the adsorbent within certain limits. In many cases, for example, in the production of cat litter, a ratio of 5.1: 1 to 6.5: 1 is preferred, for example 6: 1.

En skånsom kalcinering er vigtig for egenskaberne ved adsorptionsmidlet, der fremstilles ved fremgangsmåden ifølge 10 opfindelsen. Særligt formålstjenligt og fordelagtigt er det derfor, at kalcineringen sker ved 135-145°C. Ved disse kal-cineringstemperaturer opnås forbedret adsorptionsvirkning og hårdhed.Gentle calcination is important for the properties of the adsorbent produced by the process of the invention. Therefore, it is particularly advantageous and advantageous that the calcination occurs at 135-145 ° C. At these calcination temperatures, improved adsorption effect and hardness are obtained.

15 En kalcineringstemperatur på indtil 150° slår til i mange tilfælde. En forhøjelse af kalcineringstemperaturen til for eksempel 190°C afkorter det til kalcineringen nødvendige tidsrum. Som særlig formålstjenlig og fordelagtig har kal-cineringstemperaturer på 120-190°C fortrinsvis 160-180°C 20 vist sig.15 A calcination temperature of up to 150 ° will strike in many cases. An increase in the calcination temperature to, for example, 190 ° C shortens the time required for the calcination. As particularly useful and advantageous, calcination temperatures of 120-190 ° C have preferably been 160-180 ° C.

Særlig formålstjenligt og fordelagtigt er det også, hvis der overgås til kalciumsulfat-halvhydrat i et sådant omfang, at adsorptionsmidlet udviser et samlet vandindhold på 25 6-12 vægtprocent. På grund af en sådan kalcinering viser adsorptionsmidlet, som ud over halvhydrat også omfatter di-hydrat og anhydrit III, en fortrinlig adsorptionsvirkning.It is also particularly advantageous and advantageous if the calcium sulfate semi-hydrate is switched to such an extent that the adsorbent exhibits a total water content of 6 to 12% by weight. Due to such calcination, the adsorbent which, in addition to semi-hydrate, also comprises dihydrate and anhydrite III, exhibits an excellent adsorption effect.

Henligningen af den under vandtilsætning fremstillede gra-30 nulatblanding efter blandingen og før tørringen viser sig at være vigtig for hårdheden og afslidningsstyrken. Særlig formålstjenligt og fordelagtigt er det, hvis granulatblandingen før tørringen henligger indtil 8 minutter. I dette tidsrum kan vandets reaktion med kalciumsulfat-halvhydrat 35 forløbe fuldstændigt uforstyrret. I praksis er en henliggetid på ca. 4 minutter som regel tilstrækkelig til at få DK 171051 B1 4 et tilstrækkelig hårdt granulat, hvorved en henliggetid på indtil 5 minutter også er anvendelig.The comparison of the granulate mixture prepared under water addition after mixing and before drying proves to be important for hardness and abrasion resistance. It is particularly useful and advantageous if the granulate mixture is left to dry for up to 8 minutes before drying. During this time, the reaction of the water with calcium sulfate semi-hydrate 35 can proceed completely undisturbed. In practice, a standby time of approx. 4 minutes is usually sufficient to obtain sufficient hard granules, whereby a shelf life of up to 5 minutes is also applicable.

Adsorptionsmidlet fremstillet ved fremgangsmåden ifølge op-5 findelsen kan anvendes til væsker af uorganisk eller organisk oprindelse, for eksempel som bindemiddel for syre, lud eller olie, som også kan være blandet med vand. Adsorptionsmidlet bliver fortrinsvis anvendt som opfangningsmid-del for dyreafsondringer, for eksempel kattegrus.The adsorbent prepared by the process of the invention can be used for liquids of inorganic or organic origin, for example as an acid, liquor or oil binder which may also be mixed with water. The adsorbent is preferably used as a scavenger for animal secretions, for example, cat grit.

1010

Den dyre andel af opblæret mineral i færdigproduktet lader sig formindske med mere end 50%, hvad der udgør en tydelig omkostningsbesparelse. Adsorptionsmiddel-granulatet er å-benporet og ikke rundt, hvad der er vigtigt ved anvendelse 15 som kattegrus, fordi granulatet ikke ruller. Særlig formålstjenligt og fordelagtigt er det, hvis adsorptionsmidlet fremstilles med en løs vægt på 0,35-0,6 kg/1 fortrinsvis 0,4-0,5 kg/1, da lettere produkter skrabes ud af dyre- toilettet af kattene. Adsorptionsmidlet fremstillet ved 20 fremgangsmåden ifølge opfindelsen er hårdere og meler ikke, så at kattene ikke efterlader spor efter benyttelse af dy-retoilettet.The expensive proportion of bloated mineral in the finished product can be reduced by more than 50%, which represents a clear cost savings. The adsorbent granule is the o-bone groove and not around what is important in using cat litter because the granulate does not roll. Especially useful and advantageous is that if the adsorbent is produced with a loose weight of 0.35-0.6 kg / l, preferably 0.4-0.5 kg / l, since lighter products are scraped out of the animal toilet by the cats. The adsorbent produced by the process of the invention is harder and does not flourish so that the cats leave no trace of use of the animal toilet.

Det ved fremgangsmåden ifølge opfindelsen anvendte opblære-25 de mineral er for eksempel vermiculit, som i rå tilstand, således som det opblærede mineral, der kan komme i betragtning, er et vandholdigt mineral. Særlig formålstjenligt og fordelagtigt er det, når perlit anvendes som opblæret mineral. Perlit er ikke for eksempel gult eller brunt, men 30 hvidt og medfører på udpræget måde de egenskaber, der ønskes af det ifølge opfindelsen fremstillede middel.The inflated mineral used in the process according to the invention is, for example, vermiculite, which in the crude state, such as the considered inflated mineral, is an aqueous mineral. It is particularly useful and advantageous when pearlite is used as a bleached mineral. Perlite is not, for example, yellow or brown, but white and imparts in a distinctive manner the properties desired by the agent of the invention.

Det ifølge opfindelsen fremstillede adsorptionsmiddel lader sig ikke kun anvende til adsorptionsformål, men også under 35 andre omstændigheder, for eksempel i byggeindustrien som tilslagsmateriale i mørtelblandinger, der tager imod gips.The adsorbent prepared according to the invention can be used not only for adsorption purposes, but also under 35 other circumstances, for example in the construction industry as aggregate material in mortar mixtures which receive gypsum.

DK 171051 B1 5 Særlig formålstjenligt og fordelagtigt er det, når det ifølge opfindelsen fremstillede adsorptionsmiddel anvendes som byggematerialegranulat til udfyldning under gulve. Midlet udviser nemlig med hensyn til løsvægt, afslidning, sam-5 mentrykkelighed og styrke positive egenskaber, som gør det egnet til udfyldninger.Particularly advantageous and advantageous is when the adsorbent made according to the invention is used as building material granulate for filling under floors. Namely, the agent exhibits in terms of loose weight, abrasion, compressibility and strength positive properties which make it suitable for fillings.

Det samlede vandindhold lader sig ved kalcinering trykke ned på ca. 1 vægtprocent, hvorved en formindskelse af det 10 samlede vandindhold forøger adsorptionsvirkningen. Særlig formålstjenligt og fordelagtigt er det, hvis der ved kal-cineringen indstilles et samlet vandindhold på ca. 2 vægtprocent, ikke over 8 vægtprocent eller en værdi mellem disse to grænseværdier. Styrke, løsvægt og adsorptionsevne 15 står så i et foretrukket forhold til hinanden.The total water content can be reduced by approx. 1% by weight, thereby reducing the total water content increases the adsorption effect. It is particularly useful and advantageous if a total water content of approx. 2% by weight, not more than 8% by weight or a value between these two limit values. Strength, solubility and adsorption capacity 15 are then in a preferred relationship to each other.

Kornstørrelsen i det anvendte kornede, opblærede mineral andrager 0-6 mm, og mindst 85% af kornene i det færdige adsorptionsmiddel har en kornstørrelse større end 1,25 mm.The grain size of the grained, inflated mineral used is 0-6 mm, and at least 85% of the grains in the finished adsorbent have a grain size greater than 1.25 mm.

20 Der opstår et granulat, der er mindst 95% større end 0,8 til 6 mm. Adsorptionsmidlet omfatter i reglen større smådele, som er kalciumsulfatomhyldede opblærede mineraldele, og mindre smådele, som kun består af kalciumsulfat.20 A granulate is formed which is at least 95% larger than 0.8 to 6 mm. The adsorbent usually comprises larger small portions, which are calcium sulfate-encrusted bleached mineral parts, and smaller small portions consisting only of calcium sulfate.

25 Ved det anvendte opblærede mineral skal mindst 90% have en kornstørrelse på 1-6 mm, da mindre støvandele er uønskede. Ved det anvendte kalciumsulfat-halvhydrat skal mindst 80% fortrinsvis mindst 90% være mindre end 63 pm.25 For the bleached mineral used, at least 90% must have a grain size of 1-6 mm, since smaller dust parts are undesirable. For the calcium sulfate semi-hydrate used, at least 80%, preferably at least 90%, should be less than 63 µm.

30 Der blandes for eksempel 143 kg stukgips med 20 kg opblæret perlit, kornstørrelse 50% 0-3 mm og 50% 3-6 mm under tilsætning af 80 1 vand i en Eiriehblander i 60 sekunder. Der tilsættes ekstra vand. Vand tilsættes henholdsvis hældes i i fuld stråle. Røreværktøjets omkredshastighed andrager 6,5 35 m/sek. Der opstår et åbenporet granulat. Det fugtige granulat henligger på et langsomt løbende transportbånd før tør- DK 171051 B1 6 ring og kalcinering.For example, 143 kg of stucco is mixed with 20 kg of inflated perlite, grain size 50% 0-3 mm and 50% 3-6 mm while adding 80 l of water in an Eirieh mixer for 60 seconds. Extra water is added. Water is added or poured into full jet, respectively. The stirrer speed of the stirrer is 6.5 35 m / sec. An open-pore granule is formed. The moist granule rests on a slow-running conveyor belt before drying and calcining.

Tørrings- og kalcineringsanordningen er således indrettet, at granulatet gør så lidt gnidende bevægelse som muligt.The drying and calcining device is arranged so that the granulate makes as little rubbing motion as possible.

5 Det er vigtigt for at forhindre afslidning af det endnu fugtige materiale og for, at den åbenporede overflade bliver bibeholdt. Derfor er en tromletørrer ikke egnet, hvorimod en hvirvellags-tørrings- og kalcineringsindretning, eller en som en korntørrer arbejdende tørrings- og kalci-10 neringsindretning er egnet. Båndtørrere har vist sig som særlig brugbare, hvilke har et si-agtigt gennembrudt bånd, og ved hvilke den med gods belagt øverste del af båndet kan gennemblæses med en varm gas nedefra.5 It is important to prevent abrasion of the still moist material and to maintain the open pore surface. Therefore, a drum dryer is not suitable, whereas a vortex drying and calcining device, or a drying and calcining device working as a grain dryer. Tape dryers have proven to be particularly useful, which have a silky breakthrough band, and through which the top coated portion of the belt can be blown with a hot gas from below.

15 Tørrings- og kalcineringsanordningen er to-trins. I tørringstrinnet fjernes den frie fugtighed ved 80-100°C for eksempel 90°C. I kalcineringstrinnet behandles granulatet med ca. 130°C varm luft for at reducere det i dihydratet indeholdte krystalvand fra ca. 20% til ca. 8%. Dette trin for-20 bedrer det færdige adsorptionsprodukts adsorptionsvirkning med indtil 30%, uden slutproduktets hårdhed og dermed af-slidningen forringes mærkbart.The drying and calcining device is two-stage. In the drying step, the free moisture is removed at 80-100 ° C, for example 90 ° C. In the calcination step, the granulate is treated with approx. 130 ° C hot air to reduce the crystal water contained in the dihydrate from ca. 20% to approx. 8%. This step improves the adsorption effect of the finished adsorption product by up to 30%, without the hardness of the final product and thus the wear is significantly deteriorated.

I og for sig lader en hvilken som helst med blandeværktøj 25 forsynet blandeindretning sig anvende. Særlig formålstjenligt og fordelagtigt er det, hvis blandingen gennemføres i en beholder, der roterer, og med modsat roterende excentrisk anbragt røreværktøj, og hvis røreværktøjet i det væsentlige er udformet af flere trådagtige stænger, som i det 30 væsentlige forløber i drejeaksens retning, og er anbragt fordelt rundt omkring drejeaksen i afstand fra denne. Ved denne udformning opnås i forkortet tid en forbedret blanding, uden at alt for mange materialesmådele slås i stykker.By itself, any mixing device 25 provided with mixing tools can be used. Particularly advantageous and advantageous is if the mixture is carried in a rotating container and with the opposite rotating eccentrically arranged stirring tool, and if the stirring tool is essentially formed of several thread-like rods which extend substantially in the direction of the pivot axis, and are disposed around the pivot axis away from it. In this design, an improved mixture is obtained in a shortened time, without breaking too many material parts.

DK 171051 B1 7DK 171051 B1 7

Ved hjælp af følgende tabel skal kalcineringens og perlit-indholdets indflydelse på adsorptionen vises.The following table shows the influence of calcination and perlite content on adsorption.

5 Perlit- Samlet H20 Adsorp- Vægt- Brud- Af- indhold i færdig- tion fylde styrke slid- i færdig- produktet ved løs ifølge ning produktet form Heber- lein 10 % % % H20 g/1 N % 15 17,8 * 80 410 20 - 35 16 15 15 10,5 100 380 20 - 32 17 15 8 110 370 20 - 32 18 12 17,9* 75 440 25 - 48 7,5 12 10,1 95 430 25 - 46 8,5 12 8,6 105 410 25 - 45 10,5 20 eksemplet er ikke ifølge opfindelsen.5 Perlite- Total H20 Adsorp- Weight- Fracture- Contents in completion fill strength wear- in finished product by loose according to product form Heberlein 10%%% H20 g / 1 N% 15 17.8 * 80 410 20 - 35 16 15 15 10.5 100 380 20 - 32 17 15 8 110 370 20 - 32 18 12 17.9 * 75 440 25 - 48 7.5 12 10.1 95 430 25 - 46 8.5 12 8.6 105 410 25 - 45 10.5 The example is not according to the invention.

Til sammenligning granulat ifølge DE-PS 30 21 377 25 32 13 109 250 5-10 54For comparison, granules according to DE-PS 30 21 377 25 32 13 109 250 5-10 54

Til bestemmelse af adsorptionen (vandoptagelsesevnen) fyld-30 tes 110 g af substansen, der skulle prøves, i en cylinder. Denne cylinder er i bunden lukket med en si. Substansen, der skal testes, overhældes med 250 ml vand fra oven. Den udløbende vandmængde måles i ml. Angivelsen adsorption for eksempel 100% betyder, at et kg af granulatet kan adsorbere 35 et kg vand.To determine the adsorption (water uptake), 110 g of the substance to be tested was loaded into a cylinder. This cylinder is closed at the bottom with a sieve. The substance to be tested is poured over 250 ml of water from above. The running water volume is measured in ml. The term adsorption, for example, 100%, means that one kg of the granulate can adsorb 35 kg of water.

DK 171051 B1 8DK 171051 B1 8

Brudstyrkeprøve med tabletprøveapparat type Heberlein, 10 granulatkorn af materiale, der skal testes, med tværmål 1,5-3,5 mm afprøves med hensyn til brudstyrke. Af de ti fundne værdier dannes middelværdien og angives som brud-5 styrke i kp eller N.Fracture strength test with tablet test apparatus type Heberlein, 10 granules of material to be tested, with cross dimensions 1.5-3.5 mm tested for strength. Of the ten values found, the mean is formed and is expressed as fracture strength in kp or N.

Afslidningstest 1. 100 g granulat afsigtes på sigtemaskinen (type Sieb-10 technik Muhlheim-Ruhr) 20 cm rundsigte i 5 minutter. 3,5 mm og 250 pm sigtning og pandemateriale større end 3,5 mm og mindre end 250 pm forkastes.Abrasion test 1. 100 g granulate is sieved on the sieving machine (type Sieb-10 technik Muhlheim-Ruhr) 20 cm round sieve for 5 minutes. 3.5 mm and 250 µm sieve and pan material greater than 3.5 mm and less than 250 µm are discarded.

2. Af det sigtede materiale 250 pm - 3,5 mm fyldes 50 g 15 plus 300 g stålkugler diameter 6 mm i sigtepanden og rystes 20 minutter i sigtemaskinen.2. Of the screened material 250 µm - 3.5 mm, 50 g of 15 plus 300 g of steel balls 6 mm in diameter are filled into the sieve pan and shaken for 20 minutes in the sieving machine.

3. Til slut hældes pandens indhold på en 3,5 mm sigte, hvorved stålkuglerne fjernes. Det afsigtede materiale hæl- 20 des på ny på en 250 pm sigte og sigtes i 5 minutter. Gennemgangen gennem 250 pm sigten defineres som afslidning.3. Finally, pour the contents of the pan onto a 3.5 mm sieve, removing the steel balls. The intended material is re-poured onto a 250 µm sieve and sieved for 5 minutes. The passage through the 250 pm screen is defined as wear.

Gennemgang (g) x 100 25 Afslidning = - = x % 50 gReview (g) x 100 25 Wear = - = x% 50 g

Claims

A process for preparing an adsorbent, in particular for animal excretions, of bloated mineral and calcium sulfate semi-hydrate, in which the grain, blended mineral and calcium sulphate semi-hydrate are mixed into a granule, in which the calcium sulphate semi-hydrate is added by adding water in excess. as a whole is changed to calcium sulphate dihydrate and by which free water is removed by drying, characterized in that calcium sulphate semi-hydrate and bloated mineral are mixed in such quantities that there is a weight ratio of calcium sulphate: bloated mineral greater than 5: 1 and up to 10: 1 that the mixture is effected by the calcium sulphate semi-hydrate and the bloated mineral 15 being combined in a container and stirred with a stirring tool into a granular mixture, after the addition of water and before drying, the granulate mixture stand for at least four minutes and that the dry calcium sulphate dihydrate on calcination at 120-200 ° C to such an extent 20 is changed to calcium sulfate half hydrate, the adsorbent exhibits a total water content of 1% to 16% by weight.

Process according to claim 1, characterized in that calcium sulphate semi-hydrate and bloated mineral are stirred in such a ratio that there is in the adsorbent a weight ratio of calcium sulphate: bloated mineral of 6: 1 to 8: 1.

Process according to claim 1 or 2, characterized in that the calcination takes place at 135-145 ° C. A process according to claim 1, 2 or 3, characterized in that it is transferred to calcium sulfate half-hydrate to such an extent that the adsorbent exhibits a total water content of 6% to 12% by weight. DK 171051 B1 10

Process according to one of the preceding claims, characterized in that the granulate mixture is left standing for up to 8 minutes before drying. 5

Process according to one of the preceding claims, characterized in that the adsorbent is prepared with a bulk density of 0.35-0.6 kg / l, preferably 0.4-0.5 kg / l. 10

Process according to one of the preceding claims, characterized in that pearlite is used as a bleached mineral.

Process according to one of claims 1-3 or 5-7, characterized in that a total water content of approx. 2% by weight does not exceed 8% by weight or a value between these two limit values. 20

Process according to one of claims 1,2 or 4-8, characterized in that a calcination temperature of 120-190 ° C is used, preferably 160-180 ° C.

Method according to one of the preceding claims, characterized in that the mixture is carried out in a rotating container and with an eccentrically arranged stirring tool in the opposite direction and the stirring tool is essentially formed by a plurality of thread-like rods which extend substantially in the direction of the pivot axis and are spaced about the pivot axis away from it.

Use of the adsorbent prepared according to the process according to one of the preceding claims as a building material granulate for underfloor filling layers.