CA2049051A1

CA2049051A1 - Process for producing a soil-conditioning agent

Info

Publication number: CA2049051A1
Application number: CA002049051A
Authority: CA
Inventors: Viktor Weiss; Gunter Kofler
Original assignee: Individual
Current assignee: RHI AG
Priority date: 1989-01-13
Filing date: 1990-01-09
Publication date: 1990-07-14
Also published as: AU626984B2; EP0455677A1; YU47004B; EP0455677B1; FR2641778A1; DK0455677T3; DD297759A5; ATA5889A; LU87796A1; HRP921196A2; CS9990A2; DE3939236A1; SI9010019A; NL9020066A; WO1990008115A1; AU4965390A; HUT57685A; DE3939236C2; YU1990A; ES2049192A6

Abstract

ABSTRACT OF THE DISCLOSURE

Process for manufacturing of a granulate like product for ame-lioration of damaged and/or defective soils on the basis of a Mg-containing substance, in which finely divided Mg-carbonate is mixed with finely divided MgO under addition of water, granulated thereafter and finally the so produced granules being dried.

Description

PCT APPLICATION AS AMENDED
PROCESS FOR PRODUCING A SOIL-CONDITIONING AGENT 2 ~ 3 The invention relates to a process for manufacturing of a granu-lated product for amelioration of soils being damaged and/or defective, especially for use in agriculture and forestry.

In recent years an increasing deterioration of the growth and health of various plants has been observed. Larger parts of forest stand have got sick.

There are already larger forest areas in which the trees do not present any practical growth, leafs and needles turn yellow, fall off and die without additional external operations. Essentially the same is true in the field of agriculture.

The reasons for said deficiencies in forests have not been clari-fied totally but can be explained by the influx of harmful sub-stances from the atmosphere, causing a decrease in the pH-values within said soils and furthermore relate to malfunction of nutrient circulation in vegetation.

In this context the so-called "sour rain", i.e. the load of soils with SO2 or similar substances plays an important role.

Especially in forests the nutrient circulation plays an important role. The trees absorb essential nutrients from the soil by their roots, part of which is hold in newly formed wood, branches and needles, while an important larger part is emitted via branches, needles or leafs and then washed off by rain and transported back into the soil. Furthermore high amounts of nutrients are trans-ported back to the soil surface via leafs and needles, falling down, via fruits, dead branches and barks. While it has been thought in former times that nutrient supply for the wood could be secured by this for ever it is known today that this is not true especially for those places with pure or downgraded soils or those areas in which the nutrient circulation is disturbed by insufficient change of raw humus or spreaded use as well as in areas with high air pollution.

2~9~

In addition factors like the soil type, water addition and water removal play an important rols with respect to disturbances of nutrient circulation.

Former tests to increase the soil quality and to adjust the nutrient circulation correctly are mostly characterized by a selected mineral fertilisation, in order to add, above all, nitrogen, phosphorus and potassium, but also magnesium, calcium and trace elements to the soil.

After it had been noted that the addition of calcium to overaci-dified soils could not eliminate nutrient deficiencies charac-teristically lime, containing foreign nutrients has been used instead of limestone flour. ~ut in any case gypsum is formed and together with this an inert crust so that an influence with respect to the pH-value could be achieved but no permanent soil amelioration.

A physical mixture of a fertilizer and pellets is known from US-A-4,410,350, the latter being provided to prevent hydration of said fertilizer and thus crust forming on said fertilizer. In this respsct the pellets serve as a carrier for the fertilizer or for absorption of water respectively. They are formed by the dust from a dolomite furnace and contain large amounts of calcium oxide beneath magnesiumoxide. The described crust forming is ac-cepted consciously.

It is the object of the invention to provide a process for manu-facturing a product for amelioration of soils being damaged and/or defective to ameliorate the plant growth, especially the growth of trees effectively and not only for shorter periods but long-term whereby it is desired to achieve a continuous, time dependent successive influence of the quality of the so treated soil.

3 i~

The invention is based on the finding, neglected in former times, that supply of said soils with an sufficient amount of magnesium being important for the treatment of damaged or defective soils and the plants growing in said soils.

Magnesium as an important nutrient has to fulfill various func-tions in the plant's metabolism. It is a structural part of chlo-rophylls, ribosomes and cell wall components and is involved as a co-factor within activation of various enzymes.

It is known from tests that the magnesium content of needles from a pinetree or a spruce tree must be at least 0,03 percent by weight to secure a long time survival of the tree (so-called lethal range).

Repair of said nutrient deficiencies by said known fertilising methods mentioned above presents only a provisional solution as the effectiveness of said fertilizers is only short-term.
Furthermore magnesium is presented in known fertilizers mostly as a salt, for example as MgS04 2 H20 (kieserite) or MgS04 7 H20 (bitter salt), whereby further unwanted active substances like "S" are taken into the soil.

Furthermore the solubility rate of said magnesium compounds in said soil is constant for each product, that means that only a single temporary effect could be achieved.

Furthermore the invention has found that single use of magnesium carbonate has certain disadvantages. First the solubility of said carbonate is relatively poor. To increase it materials with high specific surfaces have to be used. Theoretically the material could be brought out in corresponding powdered form but as a 2~ ';3 powder it is difficult to handle and would blow away uncontrolled if thrown from a plane or being adsorbed by the needles and leafs if thrown off in a dry state or as a suspension and would get into the soil only little by little. It is true that preparation of said carbonates with a binder, for example magnesia cement, allows an use-specicific manufacturing, but it does not lead out of the problem that a magnesium release to said treated soils can only be achieved in long terms and within a relatively short time interval.

It is true that fertilization with magnesium oxide alone leads to a quick increase of the Mg content of said soil because of an remarkably higher solubility with respect to magnesium carbonate but at the same time problems in manufacturing and time dependent efficiency arise.

In its broadest embodiment the invention proposes a process in which fine (powdered) magnesium carbonate is mixed with fine (powdered) magnesium oxide together with a binder under addition of water, granulated thereafter and finally the so produced granules are dried thereafter to prepare a granulate like ame-lioration product.

Surprisingly the mixture of magnesium oxide and magnesium carbo-nate does not lead to a physical addition of the predescribed characteristics but a synergistic combination of both products takes place as described in more detail hereafter:

An important essential of the invention is that the basic materials are provided as finest particles. By the high surface high reaction surfaces are provided. By the addition of water during mixing of the components this water reacts with MgO under formation of magnesiumhydroxide which insofar takes over the function of an in-situ-binder and enables agglomeration and compactness of the various mixing components during granulation (pelletizing), without need of any additional binder.

~r~

During subsequent drying, which should be carried out preferably in a C02-rich atmosphere, whereby corresponding flue gases from a furnace could be used, a partial carbonization (recarbonization) of the formed reaction components can be achieved so that the following components are presented in the ready, dried product:

- MgC03 (from the original mixing component) - MgC03 (recarbonated material) - Mg(OH)2 (as a reaction product) - MgO (from the original mixing component).

As a result of increasing solubility from the carbonate via the hydroxide to the oxide there a three step reaction mechanism is offered in one product. That means that different components are presented in one product which present their effect at different times in the soil. Surprisingly it has been found that magnesium carbonate resulting from the original material and now present in the granules formed presents a lower dissolution than the recarbonated material being by the way X-ray amorph so that a fourth reaction step being formed in-situ and all this being achieved from two common Mg-containing substances in a simple process, whereby a granule like product being produced that can be distributed easily and does not blow away because of its high specific gravity and does not adhere to branches, leafs or need-les when thrown from a plane but falls immediately down onto and gets in the soil.

The different solubility coefficients of the various components of the product lead to the effect that not only a sudden effect, especially caused by the MgO component is achieved but also a long time effect up to ten years and more can be achieved (where-by then namely the carbonate from the original material will de-velop its effectiveness because of being heavy soluble).

2 ~

It seems obvious that the constituent amounts of the various re-action components depend from the original mixing ratio of said magnesium carbonate to said magnesium oxide. This should be pre-ferably in the range of 10 : 1 to 2 : 1 whereby the exact mixing ratio can be chosen as a function of the individual soil quality of the desired time dependent efficiencies respectively.

The finer the material being the higher will be the reaction sur-face and the higher will be the efficiency of the product. As well insofar the reaction of the original components with each other and with water will be influenced. Preferably the original components should be presented in a fineness of grain less than 200 ~m whereby it is preferred to present more than 50 % by weight in a fineness of grain less than 40 pm.

In this context it has to pointed out that additional ingredients can be added to the product and its original components respectively, if desired, especially to enable even a more complex soil amelioration. In this context various products are provided: It is true that small amounts of additional binders can be chosen but preferably foreign nutrients are added, dependent of the individual soil quality. Furthermore additional ingre-dients like zeolithes can be added activating the ion exchange capacity and/or the water-absorbtion capacity. Finally addition of small amounts of known fertilizers is possible although the main aspect of the invention being to present a Mg-containing product.

As already pointed out above the product can be spreaded manually or from corresponding vehicles onto the soil but it can as well be thrown from a plane flying over forests. In ea~h case the use of the described product does not lead only to a correction of the ph-value, dependent on the selected basic materials and their concentration, but does as well optimize the nutrient circulation of the plants in those soils which have been treated with the product.

Claims

WHAT IS CLAIMED:

1. Process for manufacturing of a granulate like product for ame-lioration of damaged and/or defective soils on the basis of a Mg-containing substance, in which finely divided Mg-carbonate is mixed with finely divided MgO under addition of water, granulated and the so produced granules are dried thereafter in such a way, that the final product presents MgCO3 from the basic mixing component, recarbonated MgCO3, Mg(OH)2 as a re-action product and MgO from the basic mixing component one beneath the other granulated thereafter and finally the so produced granules being dried.

2. Process according to claim 1 with the proviso that the Mg-containing basic substances are provided in a fineness of grain less than 200 µm.

3. Process according to claim 1 or 2 with a proviso that the Mg-containing substances are provided in a fineness of grain with a predominant part being 100 µm or less.

4. Process according to one of claims 1 to 3 with the proviso that the mixing components Mg-carbonate and MgO are provided in a weight ratio of 10 : 1 to 2 : 1.

5. Process according to one of claims 1 to 4 with the proviso that drying of the granules is achieved in a CO2-rich atmos-phere.

6. Process according to one of claims 1 to 5, whereby warm flue gases from a furnace are used for drying the granules.

7. Process according to one of claims 1 to 6 with the proviso that granulation is carried out so that the formed granules present an average diameter between 0,5 and 8 mm.

8. Process according to claim 7 with the proviso that granula-tion is carried out so that the formed granules present an average diameter between 1 and 4 mm.

9. Process according to one of claims 1 to 8 in which magnesia cement, sulphite liquor, molasses, carboxymethylcellulose, starch, clay, bentonite and/or fungus mycelene are added as a further binder component for granulation.

10. Process according to claim 9 in which the content of the additional binder component is limited to 20 percent by weight maximum, related to the mixing components MgO and Mg-carbonate.

11. Process according to one of claims 1 to 11 with the proviso that a substance is added to the product, activating its ion exchange capacity and/or its water absorption capacity.