MXPA00012125A - Coal combustion enhancer and method of using in blast furnace - Google Patents

Abstract

In the manufacture of iron in which coke and coal are added to a blast furnace during iron manufacture, an improvement for enhancing the operation of the furnace is disclosed. A metallic element in the form of a compound thereof, the metallic element selected from zirconium, chromium, molybdenum, tungsten, manganese, iron, cobalt, nickel, copper, zinc, aluminum, tin and lead is added to the coal, allowing for a reduction in the amount of coke added to the furnace.

Description

IMPROVING COAL COMBUSTION AND METHOD FOR USING HIGH OVEN BACKGROUND OF THE INVENTION The blast furnace method for the preparation of technical grade iron or pig iron from iron ore is essentially based on the reduction of iron oxide with carbon. The carbon used is usually in the form of coke. Due to the cost and availability of coke, this material is often partially replaced by natural gas, coal, fuel oil, etc. It is noted that it is possible to inject pulverized ore, gases or liquid petroleum products in the furnace, to promote an indirect reduction, increase the output of the blast furnace and decrease the consumption of coke, a material that is expensive to produce and convenient to replace. Many recent developments in blast furnace technology have focused on methods to partially replace costly coke with less expensive substitutes. However, with modern technology, coke can be replaced in only a proportion determined by a liquid fuel such as crude oil, tar, residual oil, or co-butane. Introducing these materials in a blast furnace to reduce the consumption of coke requires that these materials be atomized and blown in the furnace.

Unfortunately, processing of this type often results in considerable soot formation, which is both undesirable from a contamination point of view as well as unbalances the blast furnace process. In the blast furnace process, iron-containing materials including iron ore, mass formed by sintering, scrap, or other source of iron together with a fuel, usually coke, and a flux, lime, or dolomite, are loaded into the blast furnace from the top. The blast furnace burns part of the fuel to produce heat to melt the iron ore and the rest of the fuel is used to reduce the iron and its combination with coal. The load in a typical furnace, per ton of pig iron produced, is approximately 1.7 tons of ore or other materials containing iron, 0.5 - 0.65 tons of coke or other fuel and approximately 0.25 tons of lime and / or dolomite. Additionally, 1.8-2.0 tons of air are blown into the kiln during the process. It has been used pulverized coal injection for many years to reduce the use of coke and improve the operation of blast furnaces in the manufacture of ingot iron. The ability to replace coke with pulverized coal in a blast furnace can reduce contamination (since less coke is required) and can reduce the costs associated with making iron. In practice, raw materials containing iron (sinter, iron ore, nodules, etc.), fuel (coke) and flux (lime, dolomite, etc.) are loaded in the upper part of the furnace. Heated air (jet) is blown in a blast furnace through openings, which are known as nozzles at the bottom of the furnace.

Nozzle materials are adapted with injection lancets, through which supplementary fuels are injected (gas, oil and pulverized coal). The blast furnace burns the fuel and facilitates the fusion chemistry that produces iron. Blast furnace combustion gases are purified to remove particles and other noxious gases before being burned in furnaces that are used to pre-heat the jet air or in other applications, for example coke ovens, boilers, etc. DETAILED DESCRIPTION OF THE PREFERRED MODALITIES While the use of pulverized coal is common practice in blast furnace operations, the present inventors have found that the ability to replace coke with char can be greatly improved if a catalyst / auxiliary combustion is added to the coal. , preferably before being injected into the nozzles. Among the benefits derived from the use of a catalyst / auxiliary combustion are the capacity to use mineral coals of lower rank, the ability to replace more coke with coal, the reduction of the "coal cloud" (visual effect in which pulverized mineral coal injected into the nozzle remains visible as a dark cloud in the furnace), reduced loss of ignition (LOI = Loss of Ignition), reduced slag content, reduced particle emissions and superior iron quality. The coal burning auxiliary is a metallic element in the form of a compound selected from the group consisting of zirconium, molybdenum, tungsten, manganese, iron, cobalt, nickel, copper, zinc, aluminum, tin and lead. In a preferred embodiment of the present invention, the metal element is copper. In a particularly preferred embodiment, a combination of copper sulfate and a surfactant (e.g., a non-ionic surfactant, of the Triton ™ series available from Rohm & amp;; Haas) is added to the mineral coal. The following examples demonstrate the application of the present invention.

Table I Effect of Catalyst / Auxiliary of Combustion of Mineral Coal Pulverized in Operation of Blast Furnace Without Catalyst / - Catalyst Parameter Auxiliary Units of Combustion Fuel Coke Speed Kg / thm 481 457 Coke Ash% 18.96 17.88 Mineral Coal Speed Kg / thm 130 138 Fuel - Total Kg / thm 611 595 Additive ml / ton. of coal Combustion mineral 0 300-600 Blast furnace temperature ° C 1160 1175 Production speed tpd 3466 3600 Gas powder mg / Nm3 19.34 15.51 (thm: tons of hot metal) (tpd: tons per day) As illustrated in Table I above, the injection of 130 Kg / thm of pulverized mineral coal in the nozzles is 481 Kg / thm of coke added to the melt charge with a hot jet temperature of 1160 ° C, resulted in a total fuel velocity of 611 Kg / thm, and a production speed of 3,466 tpd. It should also be noted that the particulate matter in the combustion gas was 19.34 mg / Nm3. With the addition of a catalyst / auxiliary combustion (19% by weight of copper sulphate) sprayed as an aqueous solution in the coal before being sprayed and injected into the nozzles, the coke rate is reduced from 481 to 457 Kg / thm , while the speed of mineral coal increases from 130 to 138 Kg / thm. In the presence of the combustion catalyst, the total fuel velocity is reduced from 611 to 595 Kg / thm, with the hot jet temperature increasing from 1160 to 1175 ° C, and the production increasing from 3466 to 3600 tpd . It should be noted that the dust contained in the gases released is significantly reduced from 19.34 to 15.51 mg / Nm3. This decrease in dust loading demonstrates the improvement in combustion, and is consistent with the visual observation that the "coal cloud" is not observed during the auxiliary / combustion catalyst feed period. An additional evaluation was carried out, with the results summarized in Table II. As illustrated in the Table, the addition of the auxiliary / combustion catalyst resulted in a net reduction in total fuel velocity of 23 Kg / thm. This reduction in total fuel is accompanied by significant increases in production during the base uncatalyzed test period. TABLE II Effect of Catalyst / Auxiliary of Combustion of Sprayed Mineral Coal in Operation of Blast Furnace Base Period Parameter (Without Catalyst) Catalyst Coke Speed 470 459 Coke Ash 17.71 17.91 Mineral Coal Speed 125 113 Total Fuel 595 572 Combustion Additive 0 300-600 Blast Furnace Temperature 1164 1165 Production Speed 3428 3617 (Units as defined in Table I) As noted above, the auxiliary / combustion catalyst was an aqueous solution containing copper sulfate. Transition metals such as copper, are considered the most active in the last flame zone, by occlusion of the metal in the "soot", or unburned coal. Occlusion of the metal subsequently accelerates oxidation in the flame zone. It is anticipated that other materials will also be effective for purposes of the present invention. These materials include various salts of copper, barium, cobalt, manganese, as well as nitrates and alkali and alkaline earth carbonates. Furthermore, it is expected that the metal ions previously specified in conjunction with both inorganic (for example chloride, sulfate, carbonate, oxide, etc.) and organic (for example oxalate) anions as well as organometallic compounds will also be effective. While this invention has been described with respect to particular embodiments thereof, it is apparent that numerous other forms and modifications of the invention will be apparent to those skilled in the art. The appended claims and this invention will generally be considered to cover all of these obvious forms and modifications that are within the spirit and actual scope of the present invention.

Claims (10)

1. CLAIMS 1. In the manufacture of iron where mineral coal is added as a supplementary fuel to a blast furnace during manufacturing, a method to improve the furnace operation comprises adding an effective amount to improve the furnace operation and allow a reduction in the amount of coke added to the furnace of a combustion auxiliary, the combustion auxiliary is a sulfate of a metallic element selected from the group consisting of zirconium, molybdenum, tungsten, manganese, iron, cobalt, nickel, copper, zinc, aluminum, tin and lead and the method that allows reduction in the amount of coke added to the furnace.
2. 2. The method according to claim 1, characterized in that the combustion aid is combined with the coal before addition to the blast furnace.
3. 3. The method according to claim 1, characterized in that approximately 300-600 ml of the combustion aid are added per tons of mineral coal.
4. 4. The method according to claim 1, characterized in that it also comprises adding a surfactant to the mineral coal.
5. 5. The method according to claim 1, characterized in that the metal element is copper.
6. 6. In the manufacture of iron where coal is added as a supplementary fuel to a blast furnace during manufacture, a method to improve the furnace operation includes adding to the coal an effective amount to improve the furnace operation and allow a reduction in the amount of coke added to the furnace of a combustion auxiliary, the combustion aid is a sulphate of copper, barium, cobalt, manganese and their mixtures, the method allows reduction in the amount of coke added to the furnace.
7. The method according to claim 6, characterized in that the combustion aid is combined with coal before the addition to the blast furnace.
8. The method according to claim 6, characterized in that approximately 300-600 ml of the combustion rate is added per ton of mineral coal.
9. 9. The method according to claim 6, characterized in that it also comprises adding a surfactant to the mineral coal.
10. 10. The method according to claim 6, characterized in that the combustion aid is copper sulfate.