A method of obtaining a fine powder carbonyl iron

 

(57) Abstract:

The invention relates to the field of powder metallurgy, in particular the production of finely powdered carbonyl iron. The proposed method consists of cleaning liquid PENTACARBONYL iron, evaporation in the evaporator and decomposition when heated in a cylindrical reactor in the presence of gaseous ammonia, filed simultaneously with pairs PENTACARBONYL iron in the upper neck of a cylindrical reactor, and according to the invention the evaporation of PENTACARBONYL iron is carried out at the rate of feed to the evaporator 41-45 l/h, and gaseous ammonia is served in a number of 25-28 l 1 l liquid PENTACARBONYL iron, and the decomposition is carried out in the reactor divided by the heated zone, the temperature in the heated zone in the direction of the vapor PENTACARBONYL iron support: at the top 305-308oWith, in the middle 322-325oAnd at the bottom 280-290oC. Provides the carbonyl iron powder with low content of conglomerates of particles of 4% or less and with low content of bound nitrogen 0.6% and less. 1 C.p. f-crystals, 1 Il.

The invention relates to methods of obtaining iron powders and neposredstvennogo in metallurgy (manufacture of precision steel and alloys, containing pure iron), powder metallurgy (non-waste methods of obtaining parts by sintering), in electronics and in industry wired connection (ferrites and devices for negotiations), as the magnetic fillers contactless powder clutch in instrumentation and automotive, powder testing (NDT cracks, voids, etc. in large parts), industrial composites as reinforcing fillers curable matrices) and for other purposes.

A method of obtaining fine powder QOL (ed.mon. The USSR 479565, CL 22 F 9/12, 1975). In this way the liquid PENTACARBONYL iron through the dispenser with the speed 42-45 l/h served in the evaporator, the temperature of which support 106-108oC. Here a couple of PENTACARBONYL served in the upper part of the rector, this simultaneously serves gaseous ammonia with the speed of 1640 l/h Temperature in the upper and middle zones of the reactor support in the interval 345-350oWith, and in the lower zone - 320-330oC. the Disadvantage of this method is the presence of a large number of conglomerates of particles (30-35 wt.%) in the target powder QOL, as well as the presence of particles QOL large amounts of impurities nitrogen is rudovanie of powder metallurgy enterprises. - M.: metallurgy, 1988, S. 66-67), adopted as the closest analogue, including cleaning liquid PENTACARBONYL iron, evaporation in the evaporator and decomposition when heated in a cylindrical reactor in the presence of gaseous ammonia fed simultaneously from pairs of PENTACARBONYL iron in the upper neck of the cylindrical reactor.

The disadvantage of the prototype method is the existence of a large number of conglomerates of particles (30-32 wt.%) in the target powder QOL and the presence of particles of large quantities of nitrogen (0,95-1,92 wt.%).

The objective of the invention is to reduce the number of conglomerates in the target powder QOL and reduction in particle QOL nitrogen.

The technical result consists in obtaining of carbonyl iron powder with low content of conglomerates of particles of 4% or less and with low content of bound nitrogen 0.6% and less.

The technical result is achieved by the fact that in the known method of obtaining finely powdered carbonyl iron, including cleaning liquid PENTACARBONYL iron, evaporation in the evaporator and decomposition when heated in a cylindrical reactor in the presence of ammonia gas supplied in the shadow evaporation of PENTACARBONYL iron is carried out at the rate of feed to the evaporator 41-45 l/h, and gaseous ammonia serves in the number of 25-28 l 1 l liquid PENTACARBONYL iron, and the decomposition is carried out in the reactor divided by the heated zone, and the temperature in the heated zone in the direction of the vapor PENTACARBONYL iron support: in the upper - 305-308oWith, in the middle 322-325oAnd at the bottom - 280-290oC.

The proposed method of producing fine particles of QOL is as follows. Liquid PENTACARBONYL iron (Slana, Blesk) from the top of the dipstick is served at the site fine filtration, consisting of a system of three filtering devices. Then cleaned of fine particles of sooty carbon liquid Slana, Blesk flows through the filter, deep cleaning evaporator evaporator type with speed 41-46 l/h Generated in the evaporator at a temperature 109-114oWith a pair of Slana, Blesk evenly with the evaporation pdout inside vertical hollow reactor decomposition Slana, Blesk diameter 1.1 to 1.2 m and a height of 8.5-9.5 m through the upper neck of the reactor diameter 0,18-0,20 m Tangentially to the axis of the reactor decay in the same neck of the pair serves MN3heated to a temperature of 120-125oSince, in the amount of 25 to 28 liters for each liter of Slana, Blesk entering the evaporator. In the upper zone of the rector is heated to 322-325o(The"completion particle"). And finally, the lower zone of the decomposition reactor has a heat equal to 280-290oFrom ("area terazosine vapor Slana, Blesk"). The resulting decomposition Slana, Blesk carbon monoxide WITH with suspension of fine particles of QOL is fed to the recirculation gases, sequentially pass through the filter bag type (here select the fine fraction of the powder) and then through the filters and cyclones fine purification and separation (here selected more fine powder QOL). Purified from powder QOL carbon monoxide WITH using gas return in recycling decomposition Slana, Blesk, further increasing the feed rate of vapor Slana, Blesk and leading to the formation of more fine powder QOL over laminarioides mode flow.

Example 1

Liquid Slana, Blesk sent from the top of the dipstick into the site fine filtration. First, it passes the filter, where it is cleaned from mechanical impurities (coarse scale, small pieces of unreacted iron-rich pellets, dirt, etc ). In the second filter completes the cleaning of smaller solids. Finally, in the third filter special design is deep cleaning and the synthesis Slana, Blesk flow, coming from the receiver WITH pressure.

After the final cleaning from fine particles of sooty carbon liquid Slana, Blesk served in the evaporator Slana, Blesk speed 42,4 l/h Pair Fe(CO)5coming out of the evaporator at a temperature 109-110oWith send in the mixer with a diameter of 0.2 m and a height of 0.3 m, located in the upper part of the vertical reactor decomposition Slana, Blesk, having a diameter of 1.2 m and a height of the cylindrical part 9,0 m Here in the mixer, but from the side (tangentially to its axis) direct the flow of gaseous ammonia, heated to a temperature of 120oC. the Flow rate of NH3support equal to 27 liters per 1 l of liquid Fe(CO)5then there 1144,4 l/h

In the decomposition reactor Slana, Blesk support transanally temperature, providing the necessary temperature gradient for nucleation and formation of particles QOL necessary dispersion. In the upper zone temperature is equal to 306oWith, in the middle zone 325oWith and in the lower zone 290oC.

From the decomposition reactor Slana, Blesk unload 62% powder QOL with particle sizes from 0.5 to 1.9 μm. Of the filter bag for reactor decay Slana, Blesk unload 34% powder QOL with particle sizes of 0.3 to 1.9 μm. From the fine filter WITH cyclones and unload 4% more Bremerton (4% vs. 30-32% in prototype), has a low content of bound nitrogen in comparison with the prototype (less than 0.6% vs. 0.9 to 1.9 per cent in the prototype) and does not contain other undesirable impurities. With regard to impurities associated carbon and oxygen in the particles of the iron powder CVD-iron, then they are equal on each of 0.7-0.9 wt.% and not have a negative impact on its functional properties when using powders obtained QOL in all sectors of the economy, above.

Example 2 (method prototype)

Pair Slana, Blesk from the evaporator at a rate of 10 l/h served in the rector, in which at the same time introducing gaseous ammonia in the amount of 40 l per 1 l of liquid Slana, Blesk. In the upper zone of the reactor to maintain the temperature of 345oWith that in average 350oAnd at the bottom 330oC.

Get the powder QOL from the decomposition reactor in the amount of 71% with a particle size from 2.5-4.0 μm. From the filter for reactor receive 28% of the powder QOL with particle sizes of 1.7-3.5 µm. From the cyclones get 1% powder QOL with a particle size of 1.1 to 1.5 μm.

The powder has an average of 32% conglomerates of particles, and particles containing 0.9 to 1.9 wt. % bound nitrogen. The number of bound oxygen and carbon varies in the range of 0.95 to 1.76 wt.%.

1. A method of obtaining a fine powder brown heating in a cylindrical reactor in the presence of gaseous ammonia, filed simultaneously with pairs PENTACARBONYL iron in the upper neck of a cylindrical reactor, characterized in that the evaporation of PENTACARBONYL iron is carried out at the rate of feed to the evaporator 41-45 l/h, and gaseous ammonia is served in a number of 25-28 l 1 l liquid PENTACARBONYL iron, and the decomposition is carried out in the reactor divided by the heated areas.

2. The method according to p. 1, characterized in that the temperature in the heated zone in the direction of the vapor PENTACARBONYL iron support in the upper - 305-308oWith, in the middle 322-325oAnd at the bottom of 280-290oC.

 

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