Effect of the manganese ion on the crystallization process of ammonium sulfate
Abstract Generated abstract
This paper examines the use of manganese compounds as inexpensive additives for improving ammonium sulfate crystallization in coke-chemical saturator production. Laboratory crystallization experiments compared manganese sulfate, manganese-containing dye-production liquors, and sulfuric acid solutions of pyrolusite, evaluating changes in crystal size distribution and form under relevant liquid-to-solid ratios. The results indicate that small additions of manganese ion increase the yield of coarse ammonium sulfate crystals, with pyrolusite solution at 0.0025% manganese relative to solid product raising the +0.25 mm fraction from 63.0% to 87.8%. The study also reports that the crystals become stronger and more stable in form, and that about three-quarters of the introduced manganese remains in the crystalline product, producing manganized ammonium sulfate.
Full Text
Effect of the Manganese Ion on the Crystallization Process of Ammonium Sulfate
V. M. Vityugin, I. N. Nozhkina, L. M. Kovaleva
(Presented by the scientific seminar of the Department of General Chemical Technology)
In previously published works [1, 2] on the study of the influence of salts of a number of metals (Mg, Cr, Fe, and others) on the granulometric composition of crystallized ammonium sulfate, the particularly favorable effect of the magnesium ion on the growth and shape of the crystals was noted. Industrial tests carried out to verify this effect in the saturator cycle of coke-chemical production confirmed the results of laboratory studies [3]. However, as applied to the conditions of the Kemerovo Coke-Chemical Plant, the delivery of such additives as \(MgSO_4\) or \(MgCl_2\) is not economically justified; therefore, it became necessary to seek more readily available and cheaper additives.
In agricultural practice, microfertilizers introduced into the soil together with the main fertilizer have found wide application. In particular, manganese compounds are a very effective microfertilizer.
Since coke-chemical plants are, as a rule, associated in cooperation with aniline-dye and metallurgical combines, in whose production wastes manganese may be present, it was decided to test the effect of the manganese ion on the crystallization process of ammonium sulfate.
In addition to the above, manganese compounds, being oxidizing agents, should have a favorable effect on the purification of mother liquors in the saturator method of obtaining ammonium sulfate, which contain, in the form of difficult-to-remove impurities, finely dispersed oily admixtures. Surface oxidation of these impurities creates favorable conditions for their coagulation and subsequent removal.
The main attention in studying the effect of the manganese ion on the crystallization process of ammonium sulfate was directed to the following two factors: change in shape and increase in crystal size upon introduction of the manganese ion into the system.
The process of crystallization of ammonium sulfate was carried out by the method described in previous works [1, 2].
In the course of the studies it was noted that manganese in the form of the pure salt (\(MnSO_4\)) improves the sieve composition of crystalline ammonium sulfate already when introduced at 0.065% of it relative to the solid product (calculated as the \(Mn^{++}\) ion). With an increase in the additive, the yield of the coarse fraction (\(+0.25\) mm) decreases. The results of the studies are summarized in Table 1.
For the purpose of using one of the wastes from aniline-קשור...
Table 1
| No. | Crystallization conditions: additive—type | Crystallization conditions: additive—amount, % | L:S | Yield of class +0.25 mm | Sieve composition of the crystalline product, %: +0.5 mm | Sieve composition of the crystalline product, %: −0.5 mm ±0.25 mm | Sieve composition of the crystalline product, %: −0.25 mm |
|---|---|---|---|---|---|---|---|
| 1 | — | — | 1:4 | 66.9 | 15.5 | 41.4 | 33.1 |
| 2 | MnSO₄ salt | 0.065 | 1:4 | 84.5 | 22.4 | 62.1 | 15.5 |
| 3 | » | 0.125 | 1:4 | 85.4 | 32.3 | 53.1 | 15.6 |
| 4 | » | 0.25 | 1:4 | 85.4 | 30.7 | 55.4 | 13.9 |
| 5 | » | 0.5 | 1:4 | 82.0 | 30.8 | 52.1 | 17.1 |
| 6 | » | 1.0 | 1:4 | 77.4 | 18.0 | 59.4 | 22.6 |
| 7 | AKZ brine | 0.13 | 1:4 | 80.4 | 33.1 | 47.3 | 19.6 |
| 8 | » | 0.28 | 1:4 | 76.7 | 28.1 | 48.6 | 23.4 |
| 9 | » | 0.58 | 1:4 | 75.0 | 15.1 | 59.9 | 25.1 |
| 10 | — | — | 1:30 | 63.0 | 12.9 | 50.1 | 37.0 |
| 11 | Pyrolusite solution | 0.02 | 1:30 | 80.7 | 32.3 | 48.4 | 19.3 |
| 12 | » | 0.01 | 1:30 | 85.5 | 31.5 | 54.0 | 14.5 |
| 13 | » | 0.005 | 1:30 | 84.2 | 32.2 | 52.0 | 15.8 |
| 14 | » | 0.0025 | 1:30 | 87.8 | 29.4 | 58.4 | 12.2 |
| 15 | » | 0.00125 | 1:30 | 75.9 | 33.9 | 42.0 | 24.1 |
At the dye plant, a series of experiments was carried out using, as an additive, liquors from purpurine production containing manganese salts. The studies showed the fundamental possibility of using this type of liquor as an additive that improves the granulometric composition of ammonium sulfate. A drawback of these liquors, as applied to the saturator cycle, is their relatively low acidity, which leads to dilution of the mother liquors.
The most accessible form of manganese additive may be its natural compound—pyrolusite (MnO₂). Pyrolusite dissolves comparatively rapidly in sulfuric acid, after which it can be introduced into the saturator cycle. In studying the influence of pyrolusite on the crystallization process of ammonium sulfate, a suspension with a liquid-to-solid phase ratio of 1:30 was used, since approximately this ratio is maintained in the saturator bath in coke-chemical production of ammonium sulfate.
It was determined analytically that when a manganese additive is introduced into a suspension of crystallizing ammonium sulfate, 3/4 of the manganese remains in the solid product and, consequently, the ammonium sulfate obtained is manganized.
Conclusions
- The manganese ion improves the granulometric composition of ammonium sulfate in the process of crystallization of saturator liquors in coke-chemical production.
When a manganese additive is introduced in an amount of 0.0025% of the solid product, the yield of the coarse fraction (+0.25 mm) increases by more than 20% (87.8% versus 63% without the additive).
- In the presence of the manganese ion, ammonium sulfate crystals acquire a strong and stable form. Three-quarters of the manganese introduced remains in the crystalline product.
References
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V. M. Vityugin, I. N. Nozhkina. Flotation purification and crystallization of ammonium sulfate. In: Proceedings of the Fifth All-Union Conference on the Technology of Inorganic Substances and Mineral Fertilizers. Kiev, 1966.
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V. M. Vityugin, I. N. Nozhkina. Effect of microadditives of salts of certain metals on the crystallization of ammonium sulfate. Izv. TPI, vol. 148, 1967.
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V. M. Vityugin, I. N. Nozhkina, A. V. Kuzvanova. Results of pilot-plant studies on improving the granulometric composition of ammonium sulfate. Abstracts of reports of the conference “Chemistry of Kuzbass in 50 Years of Soviet Power and Prospects for Its Development.” Kemerovo, 1967.