GB1583751A

GB1583751A - Processing organic material

Info

Publication number: GB1583751A
Application number: GB12512/76A
Authority: GB
Original assignee: Trouw (UK) Ltd
Current assignee: Trouw (UK) Ltd
Priority date: 1977-06-28
Filing date: 1977-06-28
Publication date: 1981-02-04

Description

(54) IMPROVEMENTS IN OR RELATING TO PROCESSING ORGANIC MATERIAL (71) We, BP NUTRITION (U.K.) LIMITED, a British company of Steplield, Witham, Essex, CM8 3AB, 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 present invention relates to an apparatus and method for the treatment of organic material such as straw or bagasse, to render the material more digestible for ruminants.

It has been proposed hitherto to treat straw with an aqueous sodium hydroxide solution which acts to reduce the lignocellulose constituent of the straw to cellulose which is more easily digestible. The treatment according to the prior proposals commenced with drying straw to obtain an initial product and then adding an aqueous sodium hydroxide solution in a fixed amount and having a fixed water content. Such a treatment suffers from inflexibility, substantial fire risk in the drying stage and in particular necessitates an expensive drying operation.

According to the present invention there is provided a method for the preparation of animal fodder of improved digestibility for ruminants from organic material having a lignocellulose content and a varying moisture content which method comprises conveying the material to a treatment zone, continuously monitoring the varying moisture content and weight of the conveyed material and adding alkali or acid to the conveyed material in the treatment zone, the amount of alkali or acid added (calculated on a dry matter basis) being proportional to the dry weight of material conveyed and varying accordingly.

The alkali or acid can be added in aqueous solution with, if necessary, additional water to give the material in the treatment zone the desired water content.

Throughout the remainder of the descriptive part of this specification, the method according to the present invention will be described in connection with the treatment of the organic materials with alkali. Essentially similar considerations apply when the method is applied to the acid treatment of organic materials.

The possibility of varying the amount of alkali according to the moisture content of the organic material (i.e., straw or other lignocellulose - containing material) may allow it to be fed as received to the alkali-adding stage (i.e., the treatment zone) without predrying, with consequential cost saving.

This possibility depends on the use of aqueous alkali solutions of suitable strength so that the resultant treated material does not have an undesirably high water content.

The method in accordance with the invention is also more flexible than the prior proposals because it enables continuous processing of the organic material which may have a varying moisture content and weight. A higher rate of production can therefore be achieved with the possibility of further reducing production costs.

The organic material will normally first be chopped. Treatment with hammer mills can then be carried out before adding the alkali.

An apparatus for the treatment of organic material according to the invention comprises means for conveying the organic material to a treatment zone, means for continuously weighing and determining the moisture content of the conveyed organic material, means controllec by the last-mentioned means for delivering a measured amount of an alkali or acid depending on the dry weight of the conveyed organic material, and means for adding the measured amount to the organic material and for mixing it therewith.

Continuous monitoring of the moisture content and weight can be used to derive a signal to control an alkali feed device and also, if desired, a water feed device, either or both feed devices delivering to a mixer such as a paddle screw mixer.

After mixing the alkali and organic material to form a treated material having the desired weight ratio of anhydrous alkali to dry organic material, the treated material may be pelletised in a pelletising press and then passed to a cooler.

Further cooling and/or drying can be carried out in a silo which reduces fire hazards.

One particular method of carrying the invention into effect will now be described by way of example and with reference to the ac companying drawing, which is a diagram of an apparatus for performing the method to be described.

The apparatus comprises chopping devices 1 to which a raw material is fed. The raw material is conveniently an organic material such as straw but can be any other suitable lignocellulose-containing material such as bagasse, holly, hay, waste paper, wood or bracken.

The raw material having been chopped falls into an intake elevator 2 having a variable speed and incorporating a levelling device. The elevator passes the raw material to a twenty inch screw conveyor 3 and thence to hammer mills 4. After treatment in the hammer mills, the raw material falls into the hoppers 5 from which air is extracted through filters 6 by means of a fan 7. Partial air return is permitted back into the screw conveyor 3.

After collection of the raw material in the hoppers 5, the material falls to a twenty inch diameter screw conveyor 8 and is elevated by a an elevator 9 to a non-metallic chute 10 in which is located a moisture sensor. The moisture sensor includes a filter which is cleaned by air blown from an air compressor 29 which also cleans the filters 6.

The moisture content of the material having been determined by means of the moisture sensor in chute 10, the material passes to a continuous weight band 11 and is fed into a twenty inch diameter paddle screw mixer 12 which is diagrammatically shown vertical but which is in fact horizontal. In the mixer 12 there is provided a sodium hydroxide applicator 13 which is fed with an aqueous solution of sodium hydroxide by means of a variable delivery pump 14 feeding from a sodium hydroxide store tank 15. The amount of sodium hydroxide solution delivered by the pump 14 is based on the dry weight of the feed material. This is readily calculable from the moisture content and weight of the raw material. Water may also be fed into the mixer 12 by a variable delivery pump 30 if required.The amount of water fed by the pump 30 is determined by the moisture content of the raw material, the higher the latter, the less water being supplied, and the quantity of water fed with the alkali.

After mixing in the mixer 12 the raw material, now referred to as the treated material, is passed up an elevator 16 to a twenty inch diameter screw conveyor 1 7 which feeds pelletising presses 18. The treated material after pelletising is hot and is passed up an elevator 19 to a variable speed horizontal cooler 20. The cooler 20 is cooled by a fan 21 which extracts hot air from the cooler 20, any fines being returned via a cooler cyclone 22 to the screw conveyor 17.

Cooled pellets of the treated material are thcn passed te an elevator 23 and thence to a conveyor 24 wllich feeds a plurality of storage silos 25, preferably six pairs of silos. The silos are ventilated to enable the pellets to be dried and/or cooled as required.

After storage in the silos 25 the pellets are conveyed by a conveyor 26 and elevator 27 to a bulk loader hopper 28 with a convenient capacity of about twenty tons.

Control of the sodium hydroxide solution pump 14 is achieved by means of an electronic control 32 with digital read out and continuous indication and totalising means 34. The control for the water pump 30 if required is achieved by means of an electronic control 33 with a visual hydrometer and continuous indicating and recording means 35. Both controls 32 and 33 are responsive to control signals derived by a computer 31 from signal inputs received from the moisture sensor in chute 10 and the weight band 11.

In one example, the sodium hydroxide is added in the ratio equivalent to 5.5SO by weight dry solid to dry solid. The sodium hydroxide may conveniently be in the form of a 47% by weight solution in water. Weaker solutions can, however, be used down to 167O by weight. The computer calculates the rate of addition of sodium hydroxide appropriate to the concentration of the solution being added.

Whilst sodium hydroxide is mentioned as being a suitable alkali, other alkalis may conveniently be used. It is also possible that the apparatus disclosed may be used as an acid reducing system wherein an acid is substituted for the alkali to reduce the lignocellulose content of the raw material to a digestible cellulose.

WHAT WE CLAIM IS: 1. A method for the preparation of animal fodder of improved digestibility for ruminants from organic material having a lignocellulose content and a varying moisture content which method comprises conveying the material to a treatment zone, continuously monitoring the varying moisture content and weight of the conveyed material and adding alkali or acid to the conveyed material in the treatment zone the amount of alkali or acid added (calculated on a dry matter basis) being proportional to the dry weight of material conveyed and varying accordingly.

2. A method as claimed in claim 1, in which the alkali is added to the organic material in an aqueous solution.

3. A method as claimed in either of the preceding claims, in which the organic material is chopped into relatively small pieces before the alkali is added.

4. A method as claimed in any one of the preceding claims, in which the organic material is pelletised after mixing with the alkali.

5. A method as claimed in claim 4, in which the organic material is subjected to a cooling process after pelletisation.

6. Apparatus for carrying out the method in accordance with claim 1, comprising means for conveying the organic material to a treatment zone, means for continuously weighing and determining the moisture content of the con

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. companying drawing, which is a diagram of an apparatus for performing the method to be described. The apparatus comprises chopping devices 1 to which a raw material is fed. The raw material is conveniently an organic material such as straw but can be any other suitable lignocellulose-containing material such as bagasse, holly, hay, waste paper, wood or bracken. The raw material having been chopped falls into an intake elevator 2 having a variable speed and incorporating a levelling device. The elevator passes the raw material to a twenty inch screw conveyor 3 and thence to hammer mills 4. After treatment in the hammer mills, the raw material falls into the hoppers 5 from which air is extracted through filters 6 by means of a fan 7. Partial air return is permitted back into the screw conveyor 3. After collection of the raw material in the hoppers 5, the material falls to a twenty inch diameter screw conveyor 8 and is elevated by a an elevator 9 to a non-metallic chute 10 in which is located a moisture sensor. The moisture sensor includes a filter which is cleaned by air blown from an air compressor 29 which also cleans the filters 6. The moisture content of the material having been determined by means of the moisture sensor in chute 10, the material passes to a continuous weight band 11 and is fed into a twenty inch diameter paddle screw mixer 12 which is diagrammatically shown vertical but which is in fact horizontal. In the mixer 12 there is provided a sodium hydroxide applicator 13 which is fed with an aqueous solution of sodium hydroxide by means of a variable delivery pump 14 feeding from a sodium hydroxide store tank 15. The amount of sodium hydroxide solution delivered by the pump 14 is based on the dry weight of the feed material. This is readily calculable from the moisture content and weight of the raw material. Water may also be fed into the mixer 12 by a variable delivery pump 30 if required.The amount of water fed by the pump 30 is determined by the moisture content of the raw material, the higher the latter, the less water being supplied, and the quantity of water fed with the alkali. After mixing in the mixer 12 the raw material, now referred to as the treated material, is passed up an elevator 16 to a twenty inch diameter screw conveyor 1 7 which feeds pelletising presses 18. The treated material after pelletising is hot and is passed up an elevator 19 to a variable speed horizontal cooler 20. The cooler 20 is cooled by a fan 21 which extracts hot air from the cooler 20, any fines being returned via a cooler cyclone 22 to the screw conveyor 17. Cooled pellets of the treated material are thcn passed te an elevator 23 and thence to a conveyor 24 wllich feeds a plurality of storage silos 25, preferably six pairs of silos. The silos are ventilated to enable the pellets to be dried and/or cooled as required. After storage in the silos 25 the pellets are conveyed by a conveyor 26 and elevator 27 to a bulk loader hopper 28 with a convenient capacity of about twenty tons. Control of the sodium hydroxide solution pump 14 is achieved by means of an electronic control 32 with digital read out and continuous indication and totalising means 34. The control for the water pump 30 if required is achieved by means of an electronic control 33 with a visual hydrometer and continuous indicating and recording means 35. Both controls 32 and 33 are responsive to control signals derived by a computer 31 from signal inputs received from the moisture sensor in chute 10 and the weight band 11. In one example, the sodium hydroxide is added in the ratio equivalent to 5.5SO by weight dry solid to dry solid. The sodium hydroxide may conveniently be in the form of a 47% by weight solution in water. Weaker solutions can, however, be used down to 167O by weight. The computer calculates the rate of addition of sodium hydroxide appropriate to the concentration of the solution being added. Whilst sodium hydroxide is mentioned as being a suitable alkali, other alkalis may conveniently be used. It is also possible that the apparatus disclosed may be used as an acid reducing system wherein an acid is substituted for the alkali to reduce the lignocellulose content of the raw material to a digestible cellulose. WHAT WE CLAIM IS:

1. A method for the preparation of animal fodder of improved digestibility for ruminants from organic material having a lignocellulose content and a varying moisture content which method comprises conveying the material to a treatment zone, continuously monitoring the varying moisture content and weight of the conveyed material and adding alkali or acid to the conveyed material in the treatment zone the amount of alkali or acid added (calculated on a dry matter basis) being proportional to the dry weight of material conveyed and varying accordingly.

veyed organic material, means controlled by the last mentioned means for delivering a measured amount of an alkali or acid proportional to the dry weight of the conveyed organic material, and means for adding the measured amount to the organic material and for mixing it therewith.

7. Apparatus as claimed in claim 6, including a pelletising device for the treated organic material located downstream of the means for mixing the alkali or acid with the material.

8. Apparatus as claimed in claim 7, including a cooler for the treated organic material located downstream of the pelletiser.

9. A method for the preparation of animal fodder of improved digestibility for ruminants from organic materials having a lignocellulose content and a varying moisture content according to claim 1 and substantially as hereinbefore described.

10. Apparatus for treating organic material substantially as hereinbefore described with reference to the accompanying drawing.