"PROCESS FOR PRODUCTION OF WATER INSOLUBLE STABLE CONCENTRATED SUSPENSION OF COPPER COMPOUNDS (OR MIXTURES THEREOF)"

This invention comprises a process for production of stable copper compounds suspensions (herein referred to as active principles), wherein after washing the active principles for eliminating impurities, this is submitted to a pressuring stage for draining the washing water, and then is used for production of stable suspensions. In Brazil, water insoluble copper compounds concentrated suspensions are usually used in the agrochemical sector, besides being applied to other sectors, such as: a) Copper oxide: welding paste, catalysts, metallurgical industry; b) Copper hydroxide: ceramics, metallurgical industry; c) Copper oxychloride: fireworks, paints; d) Copper tribasic sulfate: veterinary industry, etc.

The traditionally used processes (refer to schematics 1 and 2) for production of concentrated suspension begin by obtaining powdered copper compounds (active principle). Each active principle is produced in a different manner and such production methodologies are not relevant for analyzing this invention.

After obtaining the active principle, the solution must be washed with water, which will be later drained. This washing is critically important for the concentrated suspension production process since contaminating chemical elements and/or compounds such as, e.g., sodium and phosphorus could react with the tense-active elements used in compounding the suspension and compromise the formulation functionality thereof.

In the traditional processes the washing and water removal stages are performed by using rotating screens, which generates the so-called active principle cake ¹ . Draining the water in the rotating screen is not a very efficient process, therefore the active principle cake do not achieve the necessary copper content for production of concentrated suspension directly from the rotating screen. Therefore, after the washing and draining stage in the rotating screen, the obtained cake must be dried by using a conventional oven (schematic 1) or spray , dryer ² (schematic 2).

After drying, the active principle agglomerates into large pieces (forming a kind of stone), it being necessary two grinding stages, one dry cake grinding stage to disaggregate the particles (turning the active principle into powder) and another grinding stage of the concentrated suspension (for reducing and homogenizing the particle size) (common stage in the schematics 1 and 2). After the first grinding (in a hammer mill), used for disaggregating the product and turning it into powder, the active principle is re-hydrated and tense-actives products, which will confer to the formulation the characteristics wanted in a , concentrated suspension are added thereto (formulation tank 1) and the product of formulation 1 is submitted to a second grinding stage (ball grinder) for homogenizing the particle size, as for the production of a concentrated suspension the particles must have an average size of up 5 μm, and in the previous grinding process the particles were just disaggregated, their size remaining quite heterogeneous; after this second grinding, a new load of tense- active products is added to the product (formulation tank 2) and after the homogenization the final product is ready to be bottled.

¹ Cake: the product resulting from passing the active principle through the screening (rotating screen or pressure screen), when such is washed and the excess water is drained.

² Spray dryer: equipment used for drying solutions with sodium content percentages lower than liquids. The process comprises the formation of a solution mist within a chamber heated through passage of hot air in a direction opposite to that of the solution.

The traditional processes require costly maintenance equipment, such as a drying system (conventional oven or spray dryer) and a ball mill (preferably of zirconium).

Such methodologies also represent environmental risks due to the burning of fuels for drying the cake and releasing of solid particles into the atmosphere, therefore requiring implementation of a monitoring system for the atmospheric emissions, aiming at controlling the environmental contamination, which increases the process price even more.

In this invention, the drying and grinding stages (compare schematic 3 with schematics 1 and 2) are eliminated. After obtaining the active principle, this is pressured and washed by using a pressure screen, which is much more efficient than the rotating screen in the water draining process as it compresses the product allowing the obtaining of a high content active principle cake. After being pressured, the cake undergoes two formulation stages (see schematic 3) for obtaining the final product and subsequent bottling.

This invention represents considerable progress in the state of the art, the main advantages thereof being: i) Elimination of the drying and grinding stages, which in addition to being pollutants (gases and solid particles emissions) are also costly, and allowing the use of the obtained cake directly into the production of the suspension; ii) the washing of the cake is more efficient in a pressure screen since the washing water goes through the inside of its frames, causing a greater contact with the cake and providing the obtaining of a dryer, and consequently content richer active principle, allowing the direct production of the concentrated suspension, in contrast to the washing performed in a rotating screen, which occurs only on the cake surface; ill) The obtained particles are more homogeneous and therefore the obtaining of a stable concentrated suspension is easier. In the traditional process, grinding

is not a guarantee of perfect homogenization of the active principle, with only one grinding pass (hammer mill that only disaggregates the aggregated particles during the drying of the product), making difficult the process for obtaining the stable concentrated suspension, a second grinding being obligatorily required (ball mill); iv) Reduction of the concentrated suspensions production time, going from six (6) to three (3) stages (compare schematics 3 with schematics 1 and 2), which represents a significant productivity increase; v) Reduction in investments in production equipment (ovens, spray dryers and mills are not required) and in atmospheric emission monitoring systems, in addition to reduction of costs with maintenance of the industrial plant for production of concentrated suspension of the copper compounds, since the process is developed with only two mixing tanks and a pressure screen.