WO2010022489A1

WO2010022489A1 - Production process of ammonium nitrate liquor

Info

Publication number: WO2010022489A1
Application number: PCT/BR2009/000276
Authority: WO
Inventors: Sérgio Gabriel COMPRIDO
Original assignee: Comprido Sergio Gabriel
Priority date: 2008-09-01
Filing date: 2009-08-27
Publication date: 2010-03-04
Also published as: BRPI0804267A2

Abstract

This invention describes a production process of Ammonium Nitrate liquor derived from Ammonium Nitrate prills with cationic coating. The new process of the product preparation presented consists of three different steps described in this invention. In the first step, this nitrate with cationic coating is put in a container which is then heated with talc and water in order to act as ancillary binding agent in anti-caking. In the next step, this solution is mixed with a polymer solution in which the two solutions react giving rise to three different phases, that is, the liquor itself, the part with polymer and impurities that are drawn off and, thus, separated, and the part with polymer that forms an emulsion that separates by flotation. In the last step of the process here described, the drawn off part is removed by a discharge and the flotation elements are extracted by multiple titrations.

Description

"PRODUCTION PROCESS OF AMMONIUM NITRATE LIQUOR"

The present invention describes a production process of Ammonium Nitrate liquor from Ammonium Nitrate prills with cationic coating.

This new preparation process of the product consists of three different steps which will be described in this invention. First, the mentioned nitrate with cationic coating is put in a container which is heated with talc and water in order to act as an ancillary binding agent in anti-caking.

In the next step, this solution is mixed with a polymer solution. In this second step of the process, these two solutions react originating three different phases, that is, the liquor itself, the part with polymer and impurities that separate by decantation, and the part with polymer that forms an emulsion that separates by flotation.

In the last step of the process here described, the drawn off part is eliminated by a discharge and the flotation elements are extracted by multiple titrations. After this cleansing, the nitrate is bleached with a solution of 200 V Hydrogen Peroxide which oxidizes the residuary organic materials deriving an Ammonium Nitrate liquor at 48% to 86% of concentration. This solution may be diluted to form solutions with varied concentrations, or concentrated to obtain a solution of up to 99% Ammonium Nitrate. Ammonium Nitrate is used as an important ingredient of explosives since

1870 when it began to partially replace nitroglycerin in dynamites. Due to its low cost, high safety and excellent performance, the Ammonium Nitrate mixture with fuel oils, the so-called ANFO (Ammonium Nitrate Fuel Oil) has quickly developed, and is currently the most applied material in the mining industry all over the world. ANFO is an explosive derived from the mixture of liquid hydrocarbons (generally diesel oil, sometimes kerosene) with Ammonium Nitrate. The destructive capacity of this compound was discovered when, in the 1920s, at a port on the Gulf of Mexico, a ship carrying fertilizers exploded after a diesel oil leakage. Besides the ANFO, other explosive materials were originated from

Ammonium Nitrate, as, for instance, the emulsion-based explosives. According to the Mining Engineer Enrique Munaretti, Master in Rock Blasting with the use of Explosives, "... these are substances able to chemically turn into gases, with extraordinary speed, producing high pressures and shock wave. During the detonation reaction of the explosive, the shock wave travels through the material with a minimum speed of 2,000 meters per second. A chemical reaction takes place within which oxygen is the oxidizing agent and carbon is the fuel (reducing agent)" (Conselho em Revista, I, no. 38, page 3/ CREA).

Explosives may be used to blast, dig and move rocks during mining operations, as well as to open road cuts, tunnels, channels, ditches or implode buildings, bridges and towers in civil construction. In the aerospace industry, they are broadly used as rocket propellers; in the automobile industry, for air- bag manufacturing, besides being used in the production of fireworks and sculptures, as, for example, Mount Rushmore in the United States. Given its high rate of effectiveness, explosives are also used in war, the nuclear ones being the most destructive.

The most primitive technique of rock blasting consisted in the heating by fire and rapid cooling of rock with cold water causing tiny cracks in it, besides the use of breaking devices such as hammers and spalling hammers. Later on, explosives like black powder, a mixture of charcoal, sulfur and sodium or potassium nitrate, substantially facilitated the rock blasting work. It is assumed that black powder derives from the "Greek Fire" (petroleum, lime and sulfur) used in 668 B.C. by a fleet of Byzantine warships. It has been recorded that, since about 1200 A. D., the Chinese, Arabs and other peoples used black powder. In early seventeenth century, black powder was introduced in mining works as the main rock breaking method in Europe, replacing the heating and cooling ones.

The most important discoveries in the field of industrial explosives nowadays employed occurred in the nineteenth century. Ascanio Sobrero, in 1846, synthesized nitroglycerin (NG), which, for its high destructive power and difficult control, was advised against for industrial use. NG was then used only as a cardiac "tonic" for its vasodilating properties.

For many years, NG aroused little interest as an explosive for its use almost always ended in tragedy. Finally, in 1862, Swedish autodidact Alfred Nobel (1833-1886) commercialized liquid nitroglycerin for mining purposes. NG was then gently poured into holes drilled in rock and detonated by means of a fuse. Considering its high sensitivity to mechanic shocks, NG was handled and transported very dangerously, which cost many lives. Thus, Nobel tried to find a way to dominate NG, figuring out a method that would allow its cushioning against mechanic shocks through the absorption of nitroglycerin mixed with some kind of material. Diatomite was the answer after several essays, and "dynamite" was the brand name given to this mixture in 1866, which was quickly marketed. Nobel also invented the fuse (1864) so that dynamite was detonated more precisely and safely. In 1895, Nobel had already built an industrial empire of at least 90 plants in 26 countries. But along his last years of life, he sadly watched his discoveries being used by the war industry. At this point he disposed of his fortune by will for the creation of annual prizes to those who best contributed to the progress of physics, chemistry, biology, medicine, and to bestow the honor of laureate upon writers and pacifists.

The "Nobel Prize" was established in 1901 by the Swedish Royal Academy of Sciences. Nowadays, explosives without nitroglycerin have been developed mainly to escape from the disadvantages in terms of safety and the high cost NG offers. The basis of these explosives is Ammonium Nitrate (AN); its addition to fuel oil was patented in 1879 by Alfred Nobel in order to be used as a partial substitute for nitroglycerin in the composition of dynamite. This salt was first synthesized in 1659 by J. R. Glauber, and applied as a fertilizer in early twentieth century.

The Second World War propelled the manufacturing of great amounts of Ammonium Nitrate not only for the composition of fertilizers but also for the ammunition industry. In the 1950s, the use of diesel oil mixed with Ammonium Nitrate in the iron ore mines of Minnesota, USA, had its onset, thus the acronym ANFO (Ammonium Nitrate Fuel Oil). In the following decades, ANFO popularized; as a result, extraction costs reduced, safety increased, and deposits that otherwise would not be economically valuable - had this technology not been accessible - turned viable. Currently, 2.5 million tons of explosives are consumed every year only in the United States, of which 97% are ANFO.

One of the weaknesses of this material is that ANFO is not water- resistant: once it comes into contact with water it does not go off. Then, along the 1960s, many explosives based on AN such as water-gel and a more resistant emulsion were created. Emulsion is the explosive that presently manages to gather all ANFO ^'s advantages in terms of safety; besides, it can be used in contact with water and still incur lower cost than dynamite.

The further applications of this product such as soil fertilization, sewage and effluents cleansing and treatment, juice production and slaughter houses disinfection are widespread.

In soil fertilization, the forms of nitric nitrogen and ammonia nitrogen may be absorbed and metabolized by plants provided they are in the NH₄ ⁺ form; the proportion of this substance in agriculture is of great importance in terms of assimilation of nitrogen by plants. Nitrogen is mainly absorbed through plant roots. According to Marschner (1995, cited in the thesis presented to the Superior School of Agriculture "Luiz de Queiroz", University of Sao Paulo, in the city of Piracicaba, State of Sao Paulo, in July, 2003), the absorption of NH/ is favored by high pH levels (alkaline medium). This absorption may result in a greater amount of absorption of anionic forms. On the other hand, it promotes a competition with basic cations enabling absorption increase of potassium, magnesium, calcium, phosphorus and sulfur. Therefore, its application should be balanced so that the reduction of Ammonium Nitrate by the vegetable organic chains is systematically taken up without harmful effects on farming. In sewage treatment, experiences performed not only by the Basic

Sanitation Company of the State of Sao Paulo (SABESP) but also by some municipalities of the State of Sao Paulo such as Santos, Sao Vicente, Monte Aprazivel and Pereira Barreto have presented good solutions to the reduction of H₂S formation in the sanitary drainage system. In the cities of Santos and Sao Vicente, the solution of Ammonium Nitrate was applied under given conditions, with concentrations varying between 10 and 50%. The application was made in lift and ejection stations in amounts equivalent to a minimum concentration of 45mg/L of Ammonium Nitrate in domestic sewage containing concentrations of hydrogen sulfide varying between 0.5 and 2.0 mg/L. To inhibit the formation of hydrogen sulfide, it has been observed that a 90 to 120-minute period of contact after the nitrate application was necessary. These applied concentrations allow the nitrate to be sufficient in proportion to take part in the cell constitution of microorganisms involved in the process (ROCHA et al., 1991 ; MORAES et al., 1993 and AZEVEDO et al., 1999).

In the status of technique, according to patent base search and specialized magazines research, several patents describing the production of Ammonium Nitrate through reactions between Ammonium Sulfate [(NH₄)₂SO₄] and Calcium Nitrate [Ca(NO₃)₂] were found, consistent with the reaction: (NH-O₂SO₄ + Ca(NO₃)₂}→ 2 NH₄NO₃+ CaSO₄. Patent US4699773 describes the reaction of Nitric Acid with Ammonium in two steps. One of them is found to have a temperature variation, and the other one presents a pressure variation. Patent US4927617 describes the reaction of Nitric Acid with ammonium in a reactor.

The processes described in the two aforementioned patents employ efficient methods but, as a matter of fact, they let relevant issues on the status of technique unresolved. These are mainly stressed because of their high production cost demand and use of raw material, the adequate amounts of which are rarely found for high-scale production once they must be imported from other supplying markets, and are not available in all countries.

In Patent PI9505880-0, the process of obtaining porous Ammonium Nitrate of low density is described. This substance is taken up from fertilizer grade prills, from solutions converted into solid particles by any kind of process, or from solid Ammonium Nitrate of some other form, a process by which, by watery means, chemical products are introduced in AN granules or any other form of Ammonium Nitrate, the reaction among which originates a gaseous product within the Ammonium Nitrate particle that causes the expansion of originally existent little cracks or bubbles creating porous Ammonium Nitrate with density varying from 0.55 to 0.85 g/crrr\ In other words, this process employs an extraction method in which commercial prills of nitrate are broken through expansion by chemical attack causing the Ammonium Nitrate liberation.

Patent PI9600121-6 describes the improvement of Patent PI9505880-0 identified above which extracts nitrate by means of the introduction of a light aqueous liquid or not adsorbed by Ammonium Nitrate, insolubilizer, or partially solubilizer and inert in Ammonium Nitrate, containing chemical reagents soluble in it, weak solubilizers or insolubilizers and inert in Ammonium Nitrate, which, reacting among themselves create gases, inert to Ammonium Nitrate, which expand internal cracks or bubbles of the Ammonium Nitrate particles, giving rise to porous Ammonium Nitrate that, when mixed with liquid fuels (in the case of ANFO), or with explosive emulsions (in the case of Emulsions Mixed with Ammonium Nitrate), or with solid fuels (in the case of Nitrocarbonitrates), one obtains explosives of low specific weight (density), of high speed and high sensitivity.

In both patents, the extracted Ammonium Nitrate still holds its coating element which characterizes an impure product liable to crystallization of the produced emulsion.

In order to solve the problems presented by the status of technique such as production high cost levels, the use of raw material difficult to obtain and the impurity of liquor, this invention describes an ongoing or intermittent production process of Ammonium Nitrate liquor. This process aims at favoring its use with greater production efficiency.

The process here described employs Ammonium Nitrate with cationic coating, which is solubilized through heating with binding agents, purified and bleached. The final result is an Ammonium Nitrate liquor with high purity levels forming a stabilized emulsion.

Initially, for the creation and development of the technology here described, one observed that the basic component for the ammonium liquor production, the object of this invention, presented a cationic coating which, if not removed, would provide a final product with a great amount of impurities, leading to the crystallization of the emulsion produced. It had also been found that this coating, if in contact with polymers of high molecular weight, reacted in a way that would make the polymer act as a molecular separator in the liquor. This evidence enabled the development of an industrial process for large-scale production of this Ammonium Nitrate liquor, solving the problems detected in the status of technique.

The production process of Ammonium Nitrate liquor described in this invention may be incorporated in the Ammonium Nitrate production industry using Ammonium Nitrate prills. Thus, the preparation process of the liquor will be described, step by step: its dilution, from purification to bleaching under controlled temperature to avoid the emulsion crystallization which causes its destabilization. a) Physical mixture of talc, water and nitrate

This preparation is made by mixing talc and water which will be homogenized and heated between 60⁰C and 140 ⁰C . Shortly after the heating,

Ammonium Nitrate prills with nonpolar or cationic coating are added, which may be in the form of prills, scales or any other form of Ammonium Nitrate for industrial use. It is noteworthy that talc, a binding agent, may present several distinct compositions such as Calcium Carbonate, Magnesium Oxide, Calcium Oxide, Alumina, among others.

Once the nitrate is diluted, the solution is ready to be purified, which occurs in the second step. b) Purification of the Ammonium Nitrate liquor

For the separation of impurities, the solution obtained in the dilution described in the step above receives an additive made up by an anionic polymer solution of high molecular weight which produces a physical separation of the material. Initially, the solution is homogenized and then left to settle for the phase separation. In this step, part of the material is drawn off and the other one floats over the Ammonium Nitrate liquor. The drawn off part is composed of talc and preexistent impurities in the Ammonium Nitrate prills. The material arising from flotation is basically composed of the mixture formed among the polymer, oils and Ammonium Nitrate. Thus, the addition of high-molecular weight anionic polymers in a relative concentration higher than 0.3% to the basic components of the Ammonium Nitrate liquor is able to purify the latter. In this step, the separation of the product is made by the rejection of the drawn off material, which can be made as often as necessary, that is, until the whole drawn off material is out of the container which can be performed by means of a discharge. This step occurs before the filtration of the suspended material. Filtration is made through filters varying between 1 to 200 micrometers according to the purity grade desired; this procedure should always begin with higher porosity to successively lower porosity levels of filters. After this purification step, liquor should undergo another step of purification which, in this procedure, is called bleaching, c) Bleaching of Ammonium Nitrate liquor

The bleaching of the Ammonium Nitrate liquor is the final step of purification when all organic matter is eliminated by oxidation. For this procedure, a 200V Hydrogen Peroxide solution is added to the purified Ammonium Nitrate. This solution must have a minimum relative proportion of 0.01 % in relation to the liquor total volume that will be submitted to bleaching, enabling the elimination of organic impurities such as carbon-based oil residues. This procedure gives rise to an Ammonium Nitrate liquor with density varying from 1.20 to 1.40 g/cm³ which can be diluted or concentrated by the addition and/or evaporation of water, or else by the addition of a given amount of dense Ammonium Nitrate, respectively.

Therefore, this invention innovates for introducing purification steps to the process of Ammonium Nitrate liquor development giving rise to a liquor that offers the advantages of higher purity of the product, removing the crystallization of the nitrate-based emulsion and consequently providing its stabilization.

Claims

CLAIMS 1. "PRODUCTION PROCESS OF AMMONIUM NITRATE LIQUOR",

CHARACTERIZED BY using Ammonium Nitrate in form of prills (granules), scales or other forms of Ammonium Nitrate, talc, water and polymer.

2. "PRODUCTION PROCESS OF AMMONIUM NITRATE LIQUOR", according to Claim 1 , CHARACTERIZED BY using heating to solubilize Ammonium Nitrate, at temperatures between 6O⁰C and 14O⁰C.

3. "PRODUCTION PROCESS OF AMMONIUM NITRATE LIQUOR", according to Claims 1 and 2, CHARACTERIZED BY the use of components such as talc, water and Ammonium Nitrate which, as they are homogenously heated and mixed, give rise to a solution of Ammonium Nitrate, not purified.

4. "PRODUCTION PROCESS OF AMMONIUM NITRATE LIQUOR", according to Claims 1,2 and 3, CHARACTERIZED BY THE FACT that talc acts as an ancillary biding agent, which can present distinct compositions such as Calcium Carbonate, Magnesium Oxide, Calcium Oxide, Alumina, among others.

5. "PRODUCTION PROCESS OF AMMONIUM NITRATE LIQUOR", according to Claims 1 to 4, CHARACTERIZED BY THE FACT that polymers act like decanting agents in relative concentration higher than 0.3%.

6. "PRODUCTION PROCESS OF AMMONIUM NITRATE LIQUOR", according to Claims 1 to 5, CHARACTERIZED BY the addition of polymer to the unpurified Ammonium Nitrate solution with the solution under stirring and afterwards set to rest until the separation of phases arising from the mixture.

7. "PRODUCTION PROCESS OF AMMONIUM NITRATE LIQUOR", according to Claims 1 to 6, CHARACTERIZED BY the use of anionic polymers of medium or high molecular weight, among which are those based on Acrylamide, not restricted.

8. "PRODUCTION PROCESS OF AMMONIUM NITRATE LIQUOR", according to Claims 1 to 7, CHARACTERIZED BY the production of a mixture with Ammonium Nitrate with three phases, to wit: one decanted with solid particles, one suspension rich in Ammonium Nitrate in the liquid phase and one suspension, sponge-like and less dense, formed mainly by polymer and oils.

9. "PRODUCTION PROCESS OF AMMONIUM NITRATE LIQUOR", according to Claim 8, CHARACTERIZED BY separating the phases originated from the mixture, with reference to Claims 1 , 2, 3 and 5, through the rejection of decanted material and filtration.

10. "PRODUCTION PROCESS OF AMMONIUM NITRATE LIQUOR", according to Claims 1 to 9, CHARACTERIZED BY the filtering of the suspended material in filters with porosities varying from 1 to 200 micrometers, according to the purity desired.

11. "PRODUCTION PROCESS OF AMMONIUM NITRATE LIQUOR", according to Claims 1 to 10, CHARACTERIZED BY the bleaching of the

Ammonium Nitrate solution proceeding from filtration.

12. "PRODUCTION PROCESS OF AMMONIUM NITRATE LIQUOR", according to Claims 1 to 11, CHARACTERIZED BY the bleaching of Ammonium Nitrate solution by adding to it a 200V Hydrogen Peroxide solution in a minimum relative proportion of 0.01 % in relation to the total volume of the liquor undergoing bleaching.

13. "PRODUCTION PROCESS OF AMMONIUM NITRATE LIQUOR", according to Claims 1 to 12, CHARACTERIZED BY producing Ammonium Nitrate in solution with density ranging from 1.20 to 1.40 g/cm3 corresponding to the concentration of 48-86% of Ammonium Nitrate.

14. "PRODUCTION PROCESS OF AMMONIUM NITRATE LIQUOR", according to Claim 13, with density ranging from 1.20 to 1.40 g/cm3, CHARACTERIZED BY resulting Ammonium Nitrate which can be diluted by the addition of water and have its concentration raised by evaporation of solvent or else by the addition of a given amount of dense Ammonium Nitrate.