GB1593058A

GB1593058A - Granulated material and process for the production of granulated materials

Info

Publication number: GB1593058A
Application number: GB46207/77A
Authority: GB
Original assignee: Bepro BV
Current assignee: Bepro BV
Priority date: 1976-11-08
Filing date: 1977-11-07
Publication date: 1981-07-15
Also published as: DE2749637C3; BE860525A; DE2749637B2; NL169143C; NL169143B; DE2749637A1; NL7612376A; LU78474A1; CH633974A5; FR2369868A1; FR2369868B1

Abstract

The granular material is porous and is used to absorb liquid and bind odours. It consists of a set mixture of cement, inorganic water-binding agents such as bentonite, sand or broken stone and, if required, colorants and/or fragrances. It is prepared by mixing the constituents with excess water, allowing the slurry to set, employing a shaping process to give a granular material, and drying this.

Description

(54) GRANULATED MATERIAL AND PROCESS FOR THE PRODUCTION OF GRANULATED MATERIALS (71) We, BEPRO B.V., a body corporate organised according to the laws of the Netherlands, of Haatlandhaven 18, Kampen, The Netherlands, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a granulated material and to a process for the production of granulated materials.

These granulated materials are suitable as materials for absorbing liquids, for example water and aqueous liquids, oil and oily liquids, and for absorbing smells. They can be used, for example, as materials for scattering on operating room floors, for example in garages, workshops and factories, to absorb spilled liquids, and also as a filling material for cat trays to absorb the liquid portion for excrement. They are also suitable as carriers for pesticides, for example, insecticides, herbicides, fungicides etc., for use in houses and operating rooms, in farming and gardening inter alia.

Hitherto granulated materials consisting of types of natural clay have been used for such purposes, for example, fuller's earth, which has a low weight by volume. These granulated materials are obtained by allowing the clay to dry in the air, breaking it up, then drying it further or calcining it, and sieving it. Both the dried and the calcined product are suitable to a greater or lesser extent for absorbing liquids. By drying or calcining, free and/or bound water is driven out and a porous material is obtained, which in the form of a granulated material ofa particle size of 0.3 to 7 mm has a weight by volume of approximately 550 g/dm3 and a water absorption of approximately 80% by weight. As a result of the fact that clay is a natural material, the properties vary from batch to batch and depending on where the clay has been obtained, and it is consequently difficult to produce a constant and uniform product.

A granulated material has been found that does not have the disadvantages of the known granulated material. The liquid and odour absorbing granulated material according to the invention is characterised in that it comprises a hardened mixture of cement, an inorganic, water-absorbing swelling agent, sand and/or ground stone and water.

The process according to the invention for producing a granulated material of this type is characterised in that cement, an inorganic water-absorbing swelling agent, sand and/or ground stone, water and if desired dyestuffs and/or perfumes and/or other additives are mixed to form a paste, the paste is allowed to harden and the hardened composition is optionally dried, and before or after hardening and/or drying made into a granulated material.

There is to be understood in this description by water-absorbing swelling agent, a substance that can absorb water and as it does so swells.

Generally these swelling agents can absorb 10 to 40 times their weight of water.

The cement, which hardens with the water, acts as a skeleton-forming substance and provides the granulated material with such a hardness that it is not easily crushed and/or pulverised when exposed to mechanical pressure during storage and/or transport.

The sand or ground stone acts as an inert blending agent to lower the cost price of the granulated material.

In order to harden, the cement requires only a few percent by weight of water based on its own weight. In the absence of other substances it can be mixed with a maximum of 35% by weight of water to form a paste. If more than 35% by weight of water to form a paste. If more than 35% by weight of water is added to the cement the excess measure of water is not retained by the composition. If only cement, to which water has been added, is processed into a granulated material having a particle size of 0.3 to 7 mm, the granulated material in the absolutely dry state has a weight by volume of approximately 800-900 g/dm and a water absorption of approximately 540% by weight.

The minimum value for the weight by volume and the maximum value for the water absorption are achieved with Portland cement class C.

These values are not, however, adequate for the intended purpose of the invention. In order to have an adequate absorbing power, a granulated material having a particle size of 0.3 to 7 mm should generally have, in the completely dry state, a maximum weight by volume of 700 g/dm3 and a water absorption of at least 45% by weight.

These values, which are advantageous for the intended purpose, are obtained in accordance with the invention by the granulated material containing, in addition to the cement as the skeleton-forming substance, a water-absorbing swelling agent. The capacity of the granulated material to absorb liquids and the weight by volume of the granulated material are connected with the volume of the pores which have a capillary action. The greater the pore volume of the hardened granulated material, the greater the amount of liquid that can be absorbed and the lower is the weight by volume.

All types of clays, for example, come into consideration as inorganic swelling agents, such as, sepiolite, montmorillonite, kaolins, and burnable types of clay. It is also possible to use diatomaceous earth. The best results are obtained with bentonite in the sodium form.

This is found naturally to a limited extent but can also be produced by a complicated activation process, which is known per se, from bentonite in the calcium form which is more readily available naturally. Where bentonite is referred to in this description, bentonite in the sodium form is meant.

The cement used may be any one of those commercially customary. The quick-setting types are preferred because of their shoft setting time. These also impart to the granulated material produced from them together with water the lowest weights by volume and the greatest water absorptions.

The blending agent used to lower the cost of the granulated material is sand of all kinds of origin, for example, dune sand, river sand and silver sand, or ground stone of natural or artificial origin. The use of silver sand is preferred because it contains fewer impurities than other types and because the distribution of the particle size is relatively constant from area to area and batch to batch.

To prepare the paste, the ratio of the weight of cement to the weight of blending agent which is generally applicable is from 55 : 45 to 65 : 35, and is preferably 60 : 40. The water content in the paste, which determines the pore volume and therefore also the liquid absorption and the pore volume after hardening and drying, also varies within relatively narrow limits, generally from 60 to 120% by weight, calculated on the total dry substance.

The content of water-absorbing swelling agent depends on the nature of the swelling agent. Generally a mixture of swelling agent and water is added to a mixture of cement and blending agent. A mixture of water-absorbing swelling agent and water that at 200C has a viscosity of 15 to 25 cP is the most suitable.

This is met, for example, by a mixture of sodium bentonite and water that contains 3-8% by weight of sodium bentonite.

By adding the water together with the waterabsorbing swelling agent the quantity of water required for the paste can be metered in accurately and absorbed into the paste.

The quantity of water worked into the paste must be such that after the mixture has hardened and dried the end product has the desired liquid-absorbing capacity, the desired weight by volume and the desired hardness. The greater the amount of cement used, the harder is the hardened product. The greater the amount of water absorbed into the mixture, the greater are the pore volume and the absorption capacity of the end product and the lower is the hardness.

The quantity of blending agent, the quantity of water-absorbing swelling agent and the plasticity of the mixture of cement, sand, swelling agent and water in the unhardened state must be such that the mixture can be spread out to form a cohesive layer and/or pressed to form particles.

Although the cement and the swelling agent as well as sand and ground stone are the essential constituents of the granulated materials, these materials may also contain other constituents. For example, the granulated materials may be made a particular colour by incorporating in the mixture to be granulated a dyestuff, for example an inorganic or organic pigment.

For example, by adding 0.3-5% by weight Fe2 03, calculated on the dry substance in the paste, to a paste of cement, bentonite, sand and water, a light cream or red-coloured granulated material can be obtained. By adding Fe2 03 the weight by volume of the granulated material is increased slightly and the water absorption reduced slightly. It is also possible to incorporate perfumes in the granulated materials.

This is advantageously carried out after drying the mixture, however, so as to prevent evaporation of the perfumes during operation. The dried material, preferably the finished granulated material, is impregnated with the perfume, which is advantageously dissolved or dispersed in a liquid.

The procedure for producing the granulated material may be as follows: The quantities of water, swelling agent, cement blending agent and optionally additives necessary for a particular batch are introduced one after the other into a mixing device. Whilst these constituents are being added the mass is continuously mixed. Once all the constituents have been combined and mixed well, the mixture is left to stand for a period, for example 1 to 3 hours, at room temperature, in order to allow the water-absorbing swelling agent and the cement to absorb water. This is particularly important in the embodiment described further below in which the mixture is made into particles before hardening. During this time the mixture stif fens, which is desirable when a granulated ma terial is to be produced. The paste becomes drier as a result of standing, and consequently during further processing does not adhere or scarcely adheres to the processing device.

The mixture thus obtained can now be further processed in a number of ways.

First of all, the mixture may be smeared or rolled into rough sheets, blocks or bars. These are allowed to harden so that they can then be broken up to form a granulated material which is optionally dried and then sieved. Another possibility is first to dry the mixture after hardening and then break it up to form a granulated material and sieve it, or alternatively first to break up the mixture into a granulated material after hardening, then sieve it and dry it.

The hardening takes place by the cement absorbing water, as a result of which it fulfils its skeleton-forming function. This hardening can be accelerated by conveying steam through or over the material from the time that the skeleton formed by the cement is no longer washed out or leached out by the condensation water formed by the steam. Steam can be used approximately 4 to 10 hours after the mixture has been produced. By heating a mixture of cement, bentonite, sand and water to approximately 800C with steam, the hardening time is shortened by approximately 30%.

The hardening process can alternatively be accelerated by the addition of calcium chloride to the mixture. The hardening time is shortened by approximately 30% by 2.5% by weight of calcium chloride, calculated on the cement.

After the material has hardened it is optionally dried, if desired having been broken up.

Drying can be effected in the air or in a cold air current, but is quicker if carried out in heated air.

For this it is possible to heat the material in still air but the material is preferably dried in a heated air current. The temperature of the air should be at least 2200C. The hardened material can be heated to approximately 350"C.

Any fine fragments or dust during the drying operation are returned to the mixing stage.

The material is then broken up, for example in ajaw crusher and/or a roll-type crusher, and the fractions of the desired particle size are isolated by sorting on sieves. Fractions that are too large are returned to the crusher whilst fractions that are too small are returned to the mixing device.

Instead of spreading the partially stiffened mixture into slabs, rough sheets or blocks, the mixture, either in the desired particle size and shape or not, can be shaped by pressing, rolling, extruding or agglomerating by means of rollers inter alia to form, for example, pellets, small rods or small blocks. The particles, thus shaped can then be hardened in the manner described hereinbefore. After the cement skeleton has become sufficiently firm, steam can be conveyed over the particles. After hardening, the particles are optionally dried and if necessary broken up and sieved. It is also possible for the particles to be broken up, dried and sieved after hardening instead of after drying. In this arrangement too, material that is too coarse is returned to the crusher and material that is too fine to the mixing device. In the case where the material is dried in the form of particles, this can be effected in a fluidised bed.

For processing the partially stiffened mixture of cement, water-absorbing swelling agent, blending agent and water the use of bentonite as swelling agent furthermore has the advantage that the so-called "green strength" of the mixture, that is the strength in the moist, unhardened state, is improved, as a result of which the mixture, owing to the better cohesion, can be handled more easily.

The granulated material according to the invention generally has, at a particle size of 0.3 to 7 mm, a weight by volume of 400 to 800 g/dm3 and a water absorption 40 to 115% by weight, calculated on completely dry granulated material. The capacity for absorbing liquids is determined by saturating with the liquid to be absorbed a weighed quantity of granulated material, of which the moisture content is known, and then weighing the granulated material again. The absorbing capacity is the percentage by weight of the absorbed liquid, calculated on the granulated material.

The granulated material obtained is excellently suited for the purposes described at the beginning of this description as well as for thermal insulation and acoustic insulation.

For use as a carrier for pesticides, the granulated material can be impregnated with a pesticide in liquid, dissolved or dispersed form.

In the following Examples, a granulated material has been produced from cement and water without a water-absorbing swelling agent.

COMPARISON EXAMPLE A 3 kg of blast furnace slag cement class A were made up into a paste with 660 ml of water. This paste was smeared to form slabs 1 cm thick which were allowed to harden at room temperature. After hardening, the slabs were broken up into a granulated material using a roll-type crusher, the fraction containing particles of a size of 0.3-7.0 mm being sieved out and dried in a drying chamber at 210 C.

This test was repeated using blast furnace slag cement class B instead of class A. The results of the tests were as follows: Class A Class B Hardening time, hours 70 70 Weight by volume, g/dm3 894 875 Water absorption, % by 12 14 weight COMPARISON EXAMPLE B Comparison Example A was repeated, except that instead of 660 ml of water, 1055 ml were used.

The results were as follows: Class A Class B Hardening time, hours 100 100 Weight by volume, g/dm3 846 839 Water absorption, % by weight 21 26 COMPARISON EXAMPLE C Comparison Example A was repeated, except that instead of blast furnace slag cement, Portland cement classes A, B and C were used, The results were as follows: Class A Class B Class C Hardening time, 70 48 24 hours Weight by vol- 877 862 853 ume g/dm3 Water absorp- 13 16 18 tion, % by wt.

COMPARISON EXAMPLE D Comparison Example B was repeated, except that Portland cement classes A, B and C were used instead of blast furnace slag cement.

The results were as follows: Class A Class B Class C Hardening time, 70 48 24 hours Weight by vol- 841 829 806 ume, g/dm3 Water absorp- 26 33 39 tion, % by wt.

The following Examples were carried out in order to show the influence of a swelling agent (bentonite) on the properties of the granulated material. In the Examples "gel" is used to mean a mixture of 15 parts by weight of bentonite and 85 parts by weight of water.

COMPARISON EXAMPLE E 3 kg of blast furnace slag cement class A were mixed thoroughly with 1.4 kg of gel. The procedure was then as in Comparison Example A.

This test was repeated with blast furnace slag cement class B instead of class A.

The results were as follows Class A Class B Hardening time, hours 76 72 Weight by volume, g/dm3 798 771 Water absorption, % by 34 41 weight COMPARISON EXAMPLE F Comparison Example E was repeated, but 2 kg instead of 1.4 kg of gel were used with 3 kg of blast furnace slag cement.

The results were as follows: Class A Class B Hardening time, hours 84 80 Weight by volume, g/dm3 631 614 Water absorption, % by 58 59 weight COMPARISON EXAMPLE G Comparison Example F was repeated, but with 2 kg of gel, 2 kg instead of 3 kg of blast furnace slag cement were used.

The results were as follows: Class A Class B Hardening time, hours 100 100 Weight by volume, g/dm3 608 611 Water absorption, % by 67 62 weight COMPARISON EXAMPLE H Comparison Example F was repeated, but 3 kg of Portland cement classes A, B and C were used instead of blast furnace slag cement with the 2 kg of gel.

The results were as follows: Class A Class B Class C Hardening time, 90 53 27 hours Weight by vol- 626 602 584 ume, g/dm3 Water absorption, 55 61 68 % by weight COMPARISON EXAMPLE J Comparison Example G was repeated, but instead of 2 kg of blast furnace slag cement, 2 kg of Portland cement classes A, B and C were used with the 2 kg of gel.

The results were as follows: Class A Class B Class C Hardening time, 96 54 27 hours Weight by vol- 612 581 536 ume, g/dm3 Water absorption, 62 69 76 % by weight COMPARISON EXAMPLE K Comparison Example J was repeated with Portland cement classes B and C, but 2.4 kg instead of 2 kg of gel were used with the 2 kg of Portland cement. As a result of the insufficient degree of hardness of the granulated material obtained with Portland cement class A, this quality of cement was not further used.

The results were as follows: Class B Class C Hardening time, hours 54 27 Weight by volume, g/dm3 570 522 Water absorption, % by 73 88 COMPARISON EXAMPLE L Comparison Example K was repeated, but 2.8 kg instead of 2.4 kg of gel were used with the 2 kg of Portland cement.

The results were as follows: Class B Class C Hardening time, hours 60 28 Weight by volume, g/dm3 549 506 Water absorption, % by 79 102 weight A number of examples illustrating the process according to the invention now follow.

"Sand" means silver sand in those examples.

EXAMPLE I 1 kg of blast furnace slag cement class B and 1 kg of sand were mixed thoroughly with 1 kg of gel. The procedure was then as in Compari- son Example A. On account of its long hardening time blast furnace slag cement class A was not examined.

The results were as follows: Hardening time, hours 92 Weight by volume, g/dln3 627 Water absorption, % by wt. 55 EXAMPLE II Example I was repeated, but 1.1 kg of blast furnace slag cement class B, 0.9 kg of sand and 2 kg of gel were used.

The results were as follows: Hardening time, hours 92 Weight by volume, g/dm3 626 Water absorption, % by wt. 57 EXAMPLE III Example II was repeated, except that 2.5 kg instead of 2 kg of gel were used with 1.1 kg of blast furnace slag cement class B and 0.9 kg of sand.

The results were as follows: Hardening time, hours 100 Weight by volume, g/dm3 609 Water absorption, % by wt. 62 EXAMPLE IV Example II was repeated, except that 1.1 kg of Portland cement classes B and C instead of blast furnace slag cement were used with 0.9 kg of sand and 2 kg of gel.

The results were as follows: Class B Class C Hardening time, hours 13 60 26 Weight by volume, g/dm3 610 543 Water absorption, % by wt. 63 75 EXAMPLE V Example III was repeated, except that 0.9 kg of Portland cement classes B and C instead of 1.1 kg of blast furnace slag cement class B and 1.1 kg instead of 0.9 kg of sand were used, with 2.5 kg of gel.

The results were approximately the same as those in Example IV except that the granulated material with class B is brittle whereas the granulated material with class C is of adequate hardness.

EXAMPLE VI Example IV was repeated, except that 3 kg instead of 2 kg of gel were used with 1.1 kg of Portland cement classes B and C and 0.9 kg of sand.

The results were as follows: Class B Class C Hardening time, hours 3 66 27 Weight by volume, g/dm3 581 514 Water absorption, % by wt. 71 97 EXAMPLE VII Example V was repeated, except that 3 kg instead of 2.5 kg of gel were used with 0.9 kg of Portland cement and 1.1 kg of sand.

The results were approximately the same as those in Example IV, but the granulated materials were rather brittle.

In the following there are a number of examples of the use of the granulated materials produced according to the invention.

USE EXAMPLE 1 On a variety of concrete floors (flagstones, Stelkon tiles, cast concrete) surface areas of 1 m2 were smeared with 300 ml of motor oil, type 10/W30. 400 g of the granulated material obtained according to Example IV with Portland cement class B were scattered onto the areas covered with oil. After 4 hours the granulated material was removed. This showed that the oil had been almost completely absorbed by the granulated material. To remove the remaining oil a further 50 g of the same granulated material was scattered onto the parts soiled by oil. After people and machines had run to and f:o over these parts of the floor for a few hours the granulated material was removed. This showed that the oil was now completely absorbed.

When the same test was carried out with household oil the oil had been completely absorbed after 45 minutes.

The same test carried out with Carter oil showed that this oil had been completely absorbed after approximately 24 hours.

USE EXAMPLE 2 A cat tray, the bottom of which was covered with a 7 cm thick layer of peat dust, sand, paper shavings or sawdust, began to smell unpleasant after only one day's use by a cat.

When instead of this filling layers of the same thickness consisting of a granulated material according to one of the Examples I to VII were used, this filling could be used for 6 to 7 days before an unpleasant smell was noticeable.

WHAT WE CLAIM IS: 1. A liquid and odour absorbing granulated material which comprises a hardened mixture of cement, an inorganic, water-absorbing swelling agent, sand and/or ground stone, and water.

2. A process for the production of a liquid and odour absorbing granulated material, wherein cement, an inorganic water-absorbing swelling agent, sand and/or ground stone, water and if desired one or more dyestuffs and/or perfumes and/or other additives are formed into a paste, the paste is caused to harden and the hardened composition is optionally dried, and before or after hardening and/or drying made into a granulated material.

3. A process according to Claim 2, wherein the weight ratio of the cement to the total of sand and/or ground stone is in the range of from 55:45 to 65:35.

4. A process according to Claim 3, wherein the said weight ratio is approximately 3:2.

5. A process according to any one of Claims 2 to 4, wherein a mixture of cement and sand and/or ground stone is formed and a mixture of the water-absorbing swelling agent and water is incorporated with the mixture so obtained.

6. A process according to any one of Claims 2 to 5, wherein the quantity of water in the paste is 60 to 120% by weight calculated on the total quantity of dry substance in the paste.

7. A process according to any one of Claims 2 to 6, wherein the inorganic, water-absorbing swelling agent comprises a clay.

8. A process according to Claim 7, wherein the clay comprises bentonite.

9. A process according to any one of Claims 2 to 8, wherein the ratio of water-absorbing swelling agent to water is such that a mixture of

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. EXAMPLE II Example I was repeated, but 1.1 kg of blast furnace slag cement class B, 0.9 kg of sand and 2 kg of gel were used. The results were as follows: Hardening time, hours 92 Weight by volume, g/dm3 626 Water absorption, % by wt. 57 EXAMPLE III Example II was repeated, except that 2.5 kg instead of 2 kg of gel were used with 1.1 kg of blast furnace slag cement class B and 0.9 kg of sand. The results were as follows: Hardening time, hours 100 Weight by volume, g/dm3 609 Water absorption, % by wt. 62 EXAMPLE IV Example II was repeated, except that 1.1 kg of Portland cement classes B and C instead of blast furnace slag cement were used with 0.9 kg of sand and 2 kg of gel. The results were as follows: Class B Class C Hardening time, hours 13 60 26 Weight by volume, g/dm3 610 543 Water absorption, % by wt. 63 75 EXAMPLE V Example III was repeated, except that 0.9 kg of Portland cement classes B and C instead of 1.1 kg of blast furnace slag cement class B and 1.1 kg instead of 0.9 kg of sand were used, with 2.5 kg of gel. The results were approximately the same as those in Example IV except that the granulated material with class B is brittle whereas the granulated material with class C is of adequate hardness. EXAMPLE VI Example IV was repeated, except that 3 kg instead of 2 kg of gel were used with 1.1 kg of Portland cement classes B and C and 0.9 kg of sand. The results were as follows: Class B Class C Hardening time, hours 3 66 27 Weight by volume, g/dm3 581 514 Water absorption, % by wt. 71 97 EXAMPLE VII Example V was repeated, except that 3 kg instead of 2.5 kg of gel were used with 0.9 kg of Portland cement and 1.1 kg of sand. The results were approximately the same as those in Example IV, but the granulated materials were rather brittle. In the following there are a number of examples of the use of the granulated materials produced according to the invention. USE EXAMPLE 1 On a variety of concrete floors (flagstones, Stelkon tiles, cast concrete) surface areas of 1 m2 were smeared with 300 ml of motor oil, type 10/W30. 400 g of the granulated material obtained according to Example IV with Portland cement class B were scattered onto the areas covered with oil. After 4 hours the granulated material was removed. This showed that the oil had been almost completely absorbed by the granulated material. To remove the remaining oil a further 50 g of the same granulated material was scattered onto the parts soiled by oil. After people and machines had run to and f:o over these parts of the floor for a few hours the granulated material was removed. This showed that the oil was now completely absorbed. When the same test was carried out with household oil the oil had been completely absorbed after 45 minutes. The same test carried out with Carter oil showed that this oil had been completely absorbed after approximately 24 hours. USE EXAMPLE 2 A cat tray, the bottom of which was covered with a 7 cm thick layer of peat dust, sand, paper shavings or sawdust, began to smell unpleasant after only one day's use by a cat. When instead of this filling layers of the same thickness consisting of a granulated material according to one of the Examples I to VII were used, this filling could be used for 6 to 7 days before an unpleasant smell was noticeable. WHAT WE CLAIM IS:

1. A liquid and odour absorbing granulated material which comprises a hardened mixture of cement, an inorganic, water-absorbing swelling agent, sand and/or ground stone, and water.

8. A process according to Claim 7, wherein the clay comprises bentonite.

those constituents has a viscosity in the range of from 15 to 25 centipoises at 20 C.

10. A process according to any one of Claims 2 to 9, wherein silver sand is used.

11. A process according to any one of Claims 2 to 10, wherein the paste mixture of water-absorbing swelling agent, cement, sand and/or ground stone and water is allowed to stand at room temperature for a period of at least 1 hour before it is processed further.

12. A process according to any one of Claims 2 to 11, wherein the paste mixture is formed into a layer, the layer is caused to harden, the hardened layer is caused to harden, the hardened layer is broken up and the broken material is either first dried and then sieved to the desired particle size, or first sieved to the desired particle size and then dried.

13. A process according to any one of Claims 2 to 11, wherein the paste mixture is formed into a layer, the layer is caused to harden, the hardened layer is dried, the dried layer is broken up and the broken material is sieved to the desired particle size.

14. A process according to Claim 12 or 13, wherein fine particles formed when the material is broken up are re-circulated to the mixing stage.

15. A process according to Claim 11, wherein the paste mixture is made into a granulated material of the desired particle shape and size, the granulated material is caused to harden and the hardened granulated material is dried.

16. A process according to any one of Claims 2 to 15, wherein, whilst the constituents are being formed into a paste, calcium chloride is added as an agent for accelerating the hardening.

17. A process according to any one of Claims 2 to 15, wherein, during hardening, steam is conveyed over or through the layer of the granulated material.

18. A process according to any one of Claims 2 to 17, wherein the hardened material is dried in a current of cold air,

19. A process according to any one of Claims 2 to 18, wherein the hardened material is dried in still or flowing hot air.

20. A process according to Claim 19, wherein the drying is carried out with air at a temperature of at least 2200C.

21. A process according to any one of Claims 2 to 20, wherein a granulated material having a particle size of 0.3 to 7 mm is produced.

22. A process according to Claim 2, conducted substantially as described in any one of Examples I to VII herein.

23. A granulated material, whenever prepared by a process as claimed in any one of Claims 2 to 22.

24. A method of absorbing a liquid, which comprises contacting the liquid with a granulated material as claimed in either Claim 1 or Claim 23.

25. A granulated material as claimed in either Claim 1 or Claim 23, impregnated with a pesticide, herbicide, insecticide or fungicide.

26. A method of providing thermal and/or acoustic insulation, which comprises establishing a layer of a granulated material as claimed in either Claim 1 or Claim 23, between regions required to be insulated.