Composite Agglomeration

Pillihuaman, A. Takano, C. Nogueira, A. Mouiao, M. Iguchi, Y Chromites reduction reaction mechanism in Carbon-Chromites composite agglomerates at 1773 K. ISIJ,... 

PREDICTION METHOD OF PRE-IGNITION BED PRESSURE DROP IN COMPOSITE AGGLOMERATION PROCESS... 

Keywords Pre-ignition bed pressure drop. Bed permeability. Composite agglomeration. Prediction method... 

Composite agglomeration process (CAP) is an iimovative method for preparing blast furnace burden[2-5]. Its principle can be summed up as 1) firstly, fine grained resources obtained from varied process are pelletized, 2) pellets are mixed into traditional sintering mixture, 3) and then the mixture is fired in sintering machine. 

CAP is characterized by several advantages such as permission of diverse iron-bearing materials in production, low fuel consumption and remarkably high productivity. Furthermore, the use of the composite agglomerates prepared by CAP is capable of obviating the negative effects caused by the differences in qualify of sinter and pellets on the operation of blast furnaces [6,7],... 

T. Jiang et al,"Composite Agglomeration Process of Iron Fines"(Patent200510032095.6 in China)... 

T. Jiang et al.,"Composite Agglomeration Process of Iron Fines", (Paper presented at 3rd International Symposium on High-Temperature Metallurgical processing, Orlando Florida. Mar,2012),7-15. 

T. Jiang et al,"Composite agglomeration process (CAP) for preparing blast furnace burden". Ironmaking Steelmaking, 37(1X2010),1-7. 

G.H. Li., et al., "Study and Application of Composite Agglomeration Process of Fluoric Iron Concentrate". Journal of Iron and Steel Research International, 16(2009),149-153. 

The Beckstead-Derr-Price model (Fig. 1) considers both the gas-phase and condensed-phase reactions. It assumes heat release from the condensed phase, an oxidizer flame, a primary diffusion flame between the fuel and oxidizer decomposition products, and a final diffusion flame between the fuel decomposition products and the products of the oxidizer flame. Examination of the physical phenomena reveals an irregular surface on top of the unheated bulk of the propellant that consists of the binder undergoing pyrolysis, decomposing oxidizer particles, and an agglomeration of metallic particles. The oxidizer and fuel decomposition products mix and react exothermically in the three-dimensional zone above the surface for a distance that depends on the propellant composition, its microstmcture, and the ambient pressure and gas velocity. If aluminum is present, additional heat is subsequently produced at a comparatively large distance from the surface. Only small aluminum particles ignite and bum close enough to the surface to influence the propellant bum rate. The temperature of the surface is ca 500 to 1000°C compared to ca 300°C for double-base propellants. 

The value of pigments results from their physical—optical properties. These ate primarily deterrniaed by the pigments physical characteristics (crystal stmcture, particle size and distribution, particle shape, agglomeration, etc) and chemical properties (chemical composition, purity, stabiUty, etc). The two most important physical—optical assets of pigments are the abiUty to color the environment in which they ate dispersed and to make it opaque. 

Classification of size enlargement methods reveals two distinct categories (8,39). The first is forming-type processes in which the shape, dimensions, composition, and density of the individual larger pieces formed from finely divided materials are of importance. The second is those processes in which creation of a coarse granular material from fines is the objective, and the characteristics of the individual agglomerates are important only in their effect on the properties of the bulk granular product. 

A water-soluble white crystalline sofld, CS is disseminated as a spray, as a cloud of dust or powder, or as an aerosol generated thermally from pyrotechnic compositions. The formulation designated CSl is CS mixed with an anti-agglomerant when dusted on the ground, it may remain active for as long as five days. CS2 formulated from CSl and a siUcone water repellent, may persist for as long as 45 days (6). 

Nomenclature. Colloidal systems necessarily consist of at least two phases, the coUoid and the continuous medium or environment in which it resides, and their properties gready depend on the composition and stmcture of each phase. Therefore, it is useful to classify coUoids according to their states of subdivision and agglomeration, and with respect to the dispersing medium. The possible classifications of colloidal systems are given in Table 2. The variety of systems represented in this table underscores the idea that the problems associated with coUoids are usuaUy interdisciplinary in nature and that a broad scientific base is required to understand them completely. 

Characterization. The proper characterization of coUoids depends on the purposes for which the information is sought because the total description would be an enormous task (27). The foUowiag physical traits are among those to be considered size, shape, and morphology of the primary particles surface area number and size distribution of pores degree of crystallinity and polycrystaUinity defect concentration nature of internal and surface stresses and state of agglomeration (27). Chemical and phase composition are needed for complete characterization, including data on the purity of the bulk phase and the nature and quaHty of adsorbed surface films or impurities. 

The composition, properties, and size of soot particles collected from flame products vary considerably with flame conditions and growth time. Typically the C—H atomic ratio ranges from two to five and the particles consist of kregular chains or clusters of tiny spheres 10—40 nm in diameter with overall dimensions of perhaps 200 nm, although some may agglomerate further to much larger sizes. 

The continuously stirred mill can be fed by screw feeders from several material bins siiTuiltaneously, thus blending uniform compositions, without incurring problems of transporting imperfectly blended or agglomerated mixtures. A series of mills may be used with decreasing media size and increasing rotary speed to achieve desired fine-particle size. No additional feed pumps are needed. 

In all such laboratory studies, plant conditions and compositions should be employed as far as possible. Agglomeration rates tend to increase with the level of supersaturation, suspension density and particle size (each of which will, of course, be related but the effects may exhibit maxima). Thus, agglomeration may often be reduced by operation at low levels of supersaturation e.g. by controlled operation of a batch crystallization or precipitation, and the prudent use of seeding. Agglomeration is generally more predominant in precipitation in which supersaturation levels are often very high rather than in crystallization in which the supersaturation levels are comparatively low. 

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