JPS5938181B2 - Fertilizer granulation method using Stephen wastewater concentrate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for granulating lime cake and other calcareous fertilizers by-produced in a sugar beet mill by adjusting the pH of a Steffen wastewater concentrate.

The lime cake used in this invention is a substance obtained by adding quicklime to the sugar solution to purify it at a sugar beet sugar factory and separating it by sedimentation, and the Steffen method (recovering saccharate from molasses as calcium saccharate). It is a general term for substances that are produced as by-products when saccharate is separated from calcium saccharate by the method of

Lime cake contains about 50% water when produced, making it extremely inconvenient to handle.

For this reason, it is deposited in a storage area for 1 to 2 years, cut back, etc., and dried under natural conditions to a moisture level of 30 to 40%.

Table 1 shows an example of the analytical values of the lime cake obtained by such natural drying.

Naturally dried lime cake has been spread on fields as an acidic soil improvement material, but recently, with the development of mechanized farming, the work of spreading fertilizers and other substances on fields has also started to be done mechanically. Partly because a machine for spreading lime cake with a high moisture content has not been developed, unused lime cake has piled up year after year, and there is no place to dispose of it.

However, dried lime cake has an extremely fine bulk specific gravity of 1.9 cc/f, a small particle size of 5 to 6 microns, and is porous, so it is too light to be spread on fields and is easily blown away by wind.

Therefore, in order to mechanically spread lime cake on fields as an agricultural calcium carbonate material, it is difficult to simply reduce the moisture content, and granulation of lime cake has become the biggest issue.

Traditionally, pulp wastewater concentrate, P
Granulation agents such as VA and CMC have been used, but in this case, 4 to 8% of granulation agents are added to lime cake to first create soft disintegrating particles, and then the moisture is gradually reduced at a low temperature to remove moisture. is 8
Pelletization was carried out by a very labor-intensive method of spraying the granulating agent again to solidify the surface of the particles when the particle size was reduced to about 1.5%.

In view of the above circumstances, this invention was developed as a result of research aimed at developing a method for easily granulating lime cake and other calcareous fertilizers.The invention adopted the Steffen method in the sugar beet sugar manufacturing process to recover sucrose from molasses. wastewater, if
That is, the concentrated liquid of Steffen wastewater is caulked, and its pm is adjusted to 3.0 to 5.5, preferably pH 4.7 to 5.2, with an inorganic or organic acid such as concentrated nitric acid, and then lime cake, etc. It has been discovered that when added to calcareous fertilizer and granulated, it can be easily granulated.

This is Steffen wastewater concentrate, and an example of its composition is shown in Table 2.
It appears as shown in.

The Steffen wastewater concentrate with the above composition does not show any granulation effect on lime cake and other fertilizer components as it is, but when its pH is adjusted to 3.0 to 5.5 with concentrated nitric acid, it can be granulated very well. The effect has been recognized, and even lime cake, which is a porous fine powder, can be granulated.

Here, when the pH is adjusted to 3.0 to 5.5 with concentrated nitric acid, etc., an extremely good granulation effect is obtained because bemain in the Steffen wastewater concentrate is in the zwitterionic form of the following formula in the above pH range. It is presumed that this is because it exists.

(CH3)3N+-CH2-COO- Then, when the pH becomes less than 3.0, salts are naturally formed with the acid and the granulation effect decreases, and when the pH becomes greater than 5.5, It is assumed that the granulation effect is reduced by forming an alkali salt.

Furthermore, when granulating lime cake using this invention, by mixing calcium carbonate and slaked lime to some extent, there is an advantage that the time required for granulation is shortened and at the same time, the hardness of the product is increased. .

The acid used to adjust the pH of the Steffen wastewater concentrate is most preferably nitric acid, but other inorganic acids or organic acids may also be used.

Examples of this invention will be shown below.

Example 1 70 m of Steffen wastewater concentrate adjusted to pH 5.0 with concentrated nitric acid was added to 500 g of lime cake containing 20 parts of water.
1 was added and mixed, granulated using a manual dish-type granulator, and dried while rotating.

Next, leave it to cool indoors (temperature 23°C, humidity 70%),
After 24 hours, the hardness of the granulated product was measured and found to be 1
．． A product of 81 g/cd was obtained.

This product was subjected to a physical property test as a prototype A1.

Example 2 Calcium carbonate powder for fertilizer 5001 was added with concentrated nitric acid.
70 m of Steffen wastewater concentrate adjusted to H4.7 was added, 6 to 8 ml of insufficient moisture for forming granules was replenished, and granules were granulated by the same means as in Example 1, followed by drying.

The hardness of the granulated product was measured after 24 hours after being left indoors to cool.2. A product with OIg/:4 was obtained.

This product was subjected to a physical property test as a prototype A2.

Example 3 Lime cake with 30% moisture 3001, calcium carbonate 1
00ff, for mixed raw material 5001 of 100g of slaked lime,
50 ml of Steffen wastewater concentrate adjusted to pH 5.1 with concentrated nitric acid was added and mixed, and the mixture was granulated and dried in the same manner as in Example 1.

The hardness of the granulated product was measured after 24 hours after being left indoors to cool. As a result, a product with a hardness of 2.0 kg/crtt was obtained.

This product was used as a prototype 3 and was subjected to physical property tests.

Example 4 Example 1. 2. The manual granulation in step 3 was magnified 10 times and carried out by a mechanical method to confirm granulation properties.

Using a pan-shaped granulator with a diameter of 1.2 m and an inclination angle of 45 degrees, lime cake 3, Okg, with a moisture content of 30%,
Steffen wastewater concentrate 500711!6 adjusted to pH 4.8 with concentrated nitric acid was added to a mixed raw material of 1.0 kg of calcium carbonate and 1.0 kg of slaked lime, and the mixture was mixed with a granulator at 13 rpm and 15+ for 10 minutes. Granulate and shape,
After that, the rotation speed was increased to 2 Orpm/min and operated for 4 minutes, and then a kerosene burner direct-fired rotary drum dryer with a diameter of 0.5 m and a length of 4.0 m was operated at a rotation speed of 5 rpm/min for 2 minutes.
Drying was performed for 0 minutes to obtain 451 kg of product.

Results of measuring the hardness of the product after cooling for 24 hours 2
．． A product of ikg/la was obtained.

This shows the same results as in Example 3 using the manual method.

Example 5 A granulation test was carried out on mixed fertilizers such as Type 1 composite fertilizers, which had a particularly large amount of organic matter and were difficult to granulate.

Ammonia sulfate, lime superphosphate, sulfuric acid, fish cake, oil cake,
A mixture of 501 and 3001 pieces of bone powder was treated with concentrated nitric acid.
Steffen wastewater concentrate with H adjusted to 5.0 was added and mixed with 60% of processed barley, and the mixture was granulated and dried while rotating.

The granulated product was subjected to the same process as in Example 1, and the hardness was measured, and as a result, a product with a hardness of 1.82 kg/=4 was obtained.

Physical property test example 1. 2. Table 3 shows the physical property test results of the granulated product obtained in step 3.

Durability Test A random sample of about 9 out of 30 products obtained by the method shown in Example 4 was sieved in advance through a 297μ sieve, and those with smaller particle sizes were excluded.

Next, put the remaining 2000S' in a plastic bag and raise it to a height of 1m.
The contents were dropped onto a concrete floor and the contents were poured again at 29.
The weight ratio of the powdered product was determined by passing it through a 7μ sieve, and the durability was tested based on this weight ratio.

The results are shown in Table-4. The above physical property tests,
As is clear from the durability test results, the granulated product obtained by this invention has a high hardness and apparent specific gravity, so it does not scatter due to the wind when sprayed on the field and has excellent disintegration properties. Therefore, after being sprayed on the field, it disintegrates and can supply fertilizer components throughout the field.

Furthermore, as is clear from the durability test results shown in Table 4, it was observed that the granulated product obtained according to the present invention did not turn into powder much even when subjected to considerable impact or rough handling during storage or transportation.

Example 6 300 g of lime cake with a moisture content of 30 parts, 1 part of calcium carbonate
00 y, for 500 g of mixed raw materials of 100 g of slaked lime,
50 ml of Steffen wastewater concentrate whose pH was adjusted in the range of 2.0 to 9.5 with concentrated nitric acid was added and mixed, and the mixture was granulated and dried in the same manner as in Example 1.

The hardness of the granulated product was measured after 24 hours after being left in a room to cool, and the results shown in Table 4(a) below were obtained.

As is clear from the above results, the p of Steffen waste wire solution is
When H is adjusted to 3.0 to 5.5, granules with sufficient hardness can be obtained, but when the pH is lower than 3.0 or higher than 5.5, it is easily powdered. However, the desired granules could not be obtained.

Reference Example 1 Add 70ml of Steffen wastewater concentrate to 500g of lime cake with a moisture content of 20%, granulate it using a manual dish-type granulator, dry it while rotating, and dry it indoors (temperature 20℃).
The granules collapsed after about 60 minutes, and the lime cake and Steffen wastewater concentrate separated and flowed out.

Reference example 2 Add 70 ml of Steffen wastewater concentrate to 500 g of calcium carbonate for fertilizer, mix, replenish 6 to 8 ml of insufficient moisture for granulation, granulate, and dry while rotating. , when left under the same conditions as Reference Example 1, about 60
After a few minutes, the granules disintegrated and a small amount of Steffen wastewater concentrate oozed out.

Reference Example 3 To 300 g of the same raw material mixture as in Example 5, Steffen wastewater concentrate 607111 and water necessary for granulation were added,
Although it was granulated and dried, it was not possible to obtain a granulated product by powdering it.

Comparative test lime cake, calcium carbonate 1001, slaked lime 100
(a) using unadjusted Steffen wastewater concentrate as a granulating agent, and using nitric acid as a granulating agent.
Table 5 below shows the granulation effect in case 1b) when the Steffen wastewater concentrate with H adjusted to 5.0 was used as the granulation agent.

Claims (1)

[Claims] 1 Steffen wastewater concentrate, which is characterized by adjusting the pH of the Steffen wastewater concentrate to 3.0 to 5.5, and adding it to lime cake and other calcareous fertilizers discarded from sugar beet factories and granulating it. Liquid fertilizer granulation method.