CS229802B1 - Treatment method of vaste acid containing molybdene - Google Patents

Description

The invention relates to a process for the treatment of waste acids containing nitric acid, sulfuric acid and molybdenum which are eliminated during leaching processes in the electrical industry.

At present, industrial fertilizers are an indispensable factor in highly intensive agricultural production. In order to maintain yield stability and crop quality, the issue of trace element fertilization is becoming increasingly important. One of these important trace elements is molybdenum, necessary especially for synbiotic nutrition mainly in clovers, as well as for the formation of cauliflower rosettes, etc. Imported ammonium or sodium molybdate in pure form is used as a source of molybdenum. In agriculture, it is applied either directly or pre-processed into solid or liquid fertilizers. The price of molybdenum rose sixfold on the world market last year.

By the process according to the invention, molybdenum for agricultural purposes, in particular for the preparation of fertilizers, can be obtained more economically by treating waste acids containing nitric acid, sulfuric acid and molybdenum from leaching processes in the electrical industry, by neutralizing with ammonia gas and / or ammonia water.

SUMMARY OF THE INVENTION The waste acids are treated with or without mixing with nitrogenous or multi-component fertilizers of nitrogenous, phosphoric or potassium-phosphoric-potassium with stirring and cooling at a temperature of from 20 ° C to 75 ° C preferably at 70 ° C with ammonia water at a concentration of 10 to 27% by weight, preferably 25% by weight / p until a pH value of 4.0 to 7.5 is reached, or optionally a gaseous ammonia is treated with a mixture of waste acids and / or fertilizers, diluted with water in a weight ratio of 0.1 to 10 to one, preferably 1: 1, until the pH of the reaction mixture is 4.0 to 7.5.

An advantage of the process according to the invention is the recovery of waste which is not yet treated, disposed of at relatively high transport costs and pollutes the waste water. In this way, molybdenum, as a trace element for agricultural purposes, is obtained at a cost two-thirds lower than when it is used in pure form; The method of processing is simple, without the need for complex apparatus. The obtained solution containing molybdenum, sulphate and ammonium nitrate can be used either for direct application by foliar fertilization, thus achieving not only faster uptake but also significantly better utilization, or the solution can be mixed with liquid nitrogen fertilizer with nitrogen content preferably above 28 ° % by weight, possibly enriched with urea, in a proportion determined by the requirements of agriculture. It is also possible to use this solution for the enrichment of solid fertilizers with nitrogen-containing trace elements or with nitrogen-phosphorus, phosphorus-potassium or nitrogen-phosphorus-potassium fertilizers with molybdenum. However, mixing with liquid nitrogen fertilizer can also be carried out prior to pH adjustment, i.e., pH adjustment. by mixing the acid waste mixture directly with the liquid nitrogen fertilizer or with the compound fertilizer before adjusting the pH of the solution with ammonia, adjusting the pH to 6.5 to 7.5 for liquid fertilizers and to 4 to 5.5 for solid fertilizers.

In order to clarify the nature of the invention, the following examples are provided to illustrate the invention without limiting it. In all exemplary embodiments, waste acids from leaching processes in the electrochemical industry are treated and the percentages are by weight.

Example 1

To 1000 kg of the waste acid mixture containing 10% nitric acid, 40% sulfuric acid and 4% molybdenum, 800 to 900 l of ammonia water of 0.91 specific gravity are added successively with stirring and cooling to a maximum temperature of 45 ° C until reaching pH 6.5 to 7.5.

Example 2

To 1000 kg of waste acid mixture containing 15% nitric acid, 36% sulfuric acid and 4.3% molybdenum, add 500 to 600 liters of water and neutralize the solution to a temperature of max. 45 ° C with ammonia gas, with stirring, obtained by gasification in a container or by ammonia waste (from waste gases) in an amount of about 200 kg of ammonia until a pH of 6.5 to 7.5 is reached. The thus prepared _n a nitrogen-molybdenum concentrate comprises about 2% of molybdenum and 10% nitrogen. The solution can be used:

(a) for direct application to plant nutrients with increased molybdenum consumption;

b) for the preparation of a liquid nitrogen fertilizer containing a trace element of molybdenum, see examples 3, 4, 5;

(c) as a molybdenum concentrate in other liquid or solid fertilizers, eg Cererit.

Example 3

To 250 g of nitrogen-molybdenum concentrate containing 2% molybdenum and 9.5% nitrogen is added 750 to 800 kg of nitrogen liquid fertilizer with a content above 28% nitrogen. After mixing, 1 to 1.050 t of finished nitrogen fertilizer is produced containing about 23% nitrogen and 0.5% molybdenum. He attaches

To 250 kg of nitrogen-molybdenum concentrate containing about 2% of molybdenum and 10% of nitrogen, urea in the amount of about 50 kg and about 700 kg of nitrogen is added according to the calculation of individual types of nitrogen (nitrate, ammonia and amide). 28%. Approximately 1 ton of nitrogen fertilizer with about 23% nitrogen and 0.5% molybdenum is produced, with a reduced nitrate nitrogen content, suitable for application at a time when its reduced dosage is required.

Example d 5

In 250 kg of nitrogen-molybdenum concentrate containing 2% molybdenum and 10 why. of nitrogen, the granular urea is dissolved in the amount as required by the customer. The liquid fertilizer obtained will contain 17% nitrogen, of which about 13 why. amide and 1.4% molybdenum.

Example 1 a d 6

1000 kg waste mixture of acids containing 14% nitric acid and 40% sulfuric acid and 4.0% molybdenum is dosed with nitrogen fertilizer solution with nitrogen content min. 28% or urea or nitrogen fertilizer solution and urea, as required for nitrate, ammoniacal and amide nitrogen contents and with cooling to 45 degrees Celsius, the whole solution is neutralized with ammonia gas or ammonia water to pH 6.5 to 7.5.

Example 7

The solution prepared according to Examples 1 to 6 can be mixed with other liquid fertilizers in the required proportion or can be used to enrich solid fertilizers, eg chlorine-free NPK fertilizers with trace elements in such a quantity that the molybdenum content meets the customer's requirements. This fertilizer should contain 0.05% molybdenum trioxide, which corresponds to a dose of 8 to 10 kg of waste acid containing about 4% molybdenum per tonne of finished, dry fertilizer.

Claims (1)

Process for the treatment of waste acids containing molybdenum, nitric and sulfuric acid from leaching processes in the electrotechnical industry, particularly suitable for the preparation of fertilizers, by neutralization with gaseous ammonia and / or ammonia water, characterized in that waste acids alone or after mixing with nitrogenous or Compound fertilizer with a nitrogen-fosforeonými, phosphoric acid-potassium or a nitrogen-phosphosilicate potassium operates while míVYNÁLEZU with stirring and cooling at a temperature of from 20 ° C to 75 ° C, preferably at 70 ^& C ammonia water having a concentration of 10 to 27 wt ° / o %, preferably 25% by weight, until a pH of 4.0 to 7.5 is reached, or optionally with gaseous ammonia, a mixture of waste acids and / or fertilizers diluted with water in a weight ratio of 0.1 to 10 to one, preferably 1: 1, until the pH of the reaction mixture is 4.0 to 7.5.