Metallurgical briquette

Dear colleagues!

 

The report on the subject The Technology and the Economy of Briquette Production from Fine-dyspersated Waste of Metallurgical and By-product-coking Plants for Economically Sound Replacement by it Traditional Mix Material of Steel, Blast-furnace and Ferroalloy Refinings and its Production Method is offered to your attention.

The urgency of the given theme arose at the turn of two contradictions originated in metallurgy industry. They are introduced on the poster 1:

On the one hand:

-   the reserves of coking coal are being steadily reduced, its price grows permanently;

-   the mining of natural iron-ore raw material is diminishing, the costs for its enrichment grow;

-   new deposits are not opened up in fact;

-   a constant growth of the rates on energy supply and rail transportation.

On the other hand:

-   the accumulated over the decades waste of metallurgical, machine-building, mining and chemical manufactures, fuel and energy complexes continues to grow. Today, if we speak about the volume and the content of useful elements, the man-caused deposits can be equated with the exploitable deposits of natural resources;

-   the location of waste near to metallurgical works;

-   huge expenditures on their opening up are not required.

The analysis of the mentioned contradictions has allowed us to formulate a scientific problem with the solution in two directions:

On the one hand:

- waste processing and utilizing and using it as a relatively cheap raw material for metallurgical manufacture, noticeably lowers expenditures on mix material and improves the quality and competitive strength, and above all lowers the net cost of the finished product.

On the other hand:

- the solution of the ecological problem of purification of whole regions where many man-caused waste deposits have been accumulated, and also reclaiming of current storage of waste of the mentioned above manufactures.

For example, for today only in the Tula region more than 17 tons of man-caused waste of metallurgical and chemical manufactures that contain compounds of different metals, first of all iron, have been accumulated. According to the experts, in Russia this figure varies from 450 up to 550 million tons, and these stocks continue to grow.

There are also quite reasonable suspicions that the real reserves of the man-caused deposits are much higher than it is officially stated.

For example, the geologists used to be given a purse for a discovered deposit, whose amount depended on its volume, that is why there was a stimulus to raise this volume too high (for example, Urengoi, where the original valuation of oil and gas reserves turned out to have been raised too high (almost two times more) in comparison to the reality).

The representatives of metallurgy, chemical and other industries understate the volume of emission in order to decrease the ecological payment that a plant pays for every ton of waste. So, you can judge about the amount of reserves of man-caused waste in your region yourself.

The volume of stocks of the man-caused deposits is comparable to the natural deposits in use.

Today Ecomashgeo Ltd has a unique technology of identification of the verges and volumes of man-caused waste deposits, located at a depth of up to 150 meters with the resolving ability up to 0.2 meters. The technology includes the apparatus Geozond - RCh, the procedure of measuring and evaluation of the results. This technology differs from the traditional geo-radar technologies as it has a better self-descriptiveness, resolving ability and depth of exploration.

The existing technologies of secondary waste utilization of different manufactures, and, first of all metallurgical, are incomplete. For example: the usage of sinter plant slurry for manufacture of agglomerate has a technological breaking point not higher than 150 kg per ton of sinter.

The dust of dry coke-quenching installations - the most valuable fuel with a high content of carbon - can be used as a material for steel scoria frothing in electric arc ovens or can be added to mix material for coking.

The experts of two corporations: Ecomashgeo Ltd and Gevit Ltd, that have been working on the development since 1997, have accumulated a major technological potential at the turn of metallurgy and building technologies and developed an essentially new method of preparation of mix material for metallurgical refining.

As a result of a long-term work the metallurgical briquette with the usage of the non-traditional binder and carbonic filler for all types of metallurgical refining has been generated, i.e. an essentially new composite mix material, whose application in metallurgy can return industry waste to metallurgical refining as raw material with a high profitability.

The manufacture of such briquettes will allow to essentially improve performance characteristics of the refining at your plants and thus improve the ecological situation.

The complex scheme of the waste utilization is shown on the poster 2, from which we see, that to the machine industry waste it is possible to refer:

-   roll scale and forge cinder

-   iron and steel cuttings

- metal sifting

- aspiration settings dust

To the metallurgy industry waste it is possible to refer:

- blast-furnace dust;

- aspiration settings dust;

- scorias and slurries;

- roll scale;

- coke breeze and dust.

To the coal mining industry waste can be referred:

- coal fines and dust;

- slurry;

- mill tailings.

To the by-product-coking industry waste it is possible to refer:

- coke breeze and dust;

- resin.

To the fuel and energy complex waste it is possible to refer:

- ashes

- finely pulverized coal.

To the wood industry waste it is possible to refer:

- charcoal fine

- lignosulphonates

- wood waste

- etc.

 

All these can be utilized by the method of cold sintering.

Sintering is one of the actual problems in preparation of iron-containing materials for metallurgical refining.

For today there are three known methods of sintering of small-sized ores, concentrates and waste. They are agglomeration, granulation (pelletizing) and briquetting.

Agglomeration is a process of generation of pieces (agglomerate) by the method of sintering of small-sized ores and a concentrate with the fuel material at a high combustion temperature. Due to high temperature during the sintering process a part of hazardous admixtures (for example sulfur) is sublimed.

Pelletizing is a process of generation of pellets, based on the character of the humidified atomized ore particles or a concentrate to organize a pellet of a greater or smaller size and durability, that is put into the necessary size and shape by rolling in special devices, the following sintering gives extra durability.

Briquetting is a process of generation of pieces (briquettes) with adding and without adding binder materials with the following pressing the mixture into briquettes of the necessary size and shape.

In Russia at present about 52 million tons of agglomerate and 30 million tons of pellets are fabricated. At the same time there isnt a single producer of metallurgical briquettes who would use the method of cool vibratory compaction. It means that there isn't a single ton of fabricated briquette in industrial volumes.

Though briquetting in ferrous metallurgy is one of the earliest methods of sintering, which was widely used for this purpose in second half of the 19th century, at the beginning of the 20th century briquetting was ousted by agglomeration. There were several reasons for that, the main of them was the diseconomy as the low-power presses had a low productivity, while in agglomeration the machines with the productivity of more than 2000 tons of agglomerate per day were generated.

For today the technological progress has reached such a level, when it is possible to briquette more than 5000 tons of raw material per day and this method is pollution-free.

To the doubtless advantages of briquette it is possible to refer the following ones:

-   briquettes are regularly shaped and have identical weight, contain more metal in the

given volume, have a higher durability and a better transportability;

-   have a higher relative density;

-   the ecological safety of briquettes (wastelessness, absence of high temperature during the production process);

-   the possibility of using (in any ratio) in briquette some carbonic filler for activation of the processes in the metallurgical oven (carbonizer, regenerator, energy carrier);

-   the possibility of using all types of fine iron-flux-alloy-carbon-containing waste of

metallurgical refining.

The ultimate strength, density and porosity of briquette are taken as the parameters. They are reached in the prescribed limits by influencing on mix material by unit pressure 0,025-0,09 Pa, vibration with frequency of 35-65 Hz and vibrational amplitude 0,25-0,55 mm up to a condition, that ensures reaching the required setting values of these parameters, thus the humidification is done before obtaining the water-binding ratio, fixed for the given mix.

During the development of the briquette production technology we had the following priority objectives:

-   to obtain the briquette with the specified characteristics on demand of a definite customer (this technology gives the opportunity to obtain the briquette with the specified geometrical proportions and physical properties)

-   the composition of the briquette which defines its metallurgical value is developed by the specialists - the metallurgists of the plant - briquette consumers.

-   the effectiveness of the briquette production and usage, that is reached by locating of the briquette plant near to the waste deposits and melting units, that are usually situated next to each other.

-   high productivity, low net cost of the vibropress equipment, minimal operating staff (the vibropress Rukis with the productivity up to 8000 tons of briquette a month is served by 5 persons per shift).

One more direction of the research is the analysis of the influence of the shape and geometrics of briquette on the metallurgical properties of the mix material.

Let us see the traditional scheme of preparation of the mix material for steel melting and according to our technology, which are shown on the poster 3.

We do not consider the processes of mix material production for steel refining, that are connected with the direct reduction of iron and melts in the fluid pot, such as Midrex, Korex, Hill, Finmet, Rawmelt, Hissmelt, etc, though for these processes it is possible to use briquetted mix material.

The traditional method of transportation of iron and fuel to the filling and rolling stations is rather long, energy intensive and costs much. This method is known to everybody and consists of the following stages:

-   geological exploration and opening up of the deposits;

-   mining and enrichment of the iron-ore raw material and coal;

-   the production of iron-ore pellets, agglomerate and coal coke;

-   blast-furnace refining with its product - hot metal and pig-iron as well as Synthicom;

-   steel production by the known processes (open-hearth, converter, electric furnace).

At every stage waste is generated. Its metallurgical value is very high and it has not been completely realized. Among it: roll and forge scale, aspiration setting dust, ashes, blast-furnace dust, sludge, pig-iron and steel cuttings, coke breeze and others. The offered by us technology gives you the opportunity to avoid three capacious and expensive technological processes (the poster 3).

The specialists will ask about the excessive content of the detrimental impurities in the used waste (sulphur, phosphorus, alkali, non-ferrous metals and others). I would like to say that when smelting pure special steel it is possible to use high-purity materials:

-   highly enriched iron concentrates;

-   charcoal;

-   pyrolytic carbon, graphite;

-   etc.

Briquette can be one of the components of the mix material, that will supplement the traditional steel waste, hot metal or pig-iron. Though during the smetlings at the Tiazhpromarmatura Public Cooperation (the town Aleksin, Tula Region) pig-iron was completely replaced by iron-carbon briquette.

The usage of briquette gives steelmakers the opportunity (arc electro smelting furnace) to use two components of the mix material: steel waste and iron-carbon briquette.

The actual objective of the steelmakers is the problem of carbon: there is too much of it (converter), or too little (open-hearth and electric furnace ovens). In briquette it is possible to have 50% of carbon by mass. In the same way the briquette (-, -) is fabricated, whose basic part consists of FeO.

The manner of interaction of iron oxide and carbon in the melting process is presented in the report of NPMP Intermet-Service The peculiarities of the kinetics of the carbon oxidizing in the compositional mix material Synthicom.

So, how could we provide the unique characteristics of briquette?

As it has already been said, this problem was solved at the turn of two technologies: metallurgy and production of building materials.

Briquetting in metallurgy had been known before agglomeration and pelletizing, but it was not widely spread because of the absence of highly productive, safe and cheap equipment for its production.

The specialists of Ecomashgeo Ltd and Gevit Ltd have developed the ways of updating the typical vibropress equipment with the aim of its adjustment to the metallurgical briquette production.

The technological scheme of metallurgical briquette production is shown on the poster 4, where we can see the basic technological blocks:

-   intake and storing of loose materials;

-   feeding of the mix material;

-   preparation of the mix material in the blending machine;

-   molding;

-   transportation to the station of the strength development;

-   packaging and transportation of briquettes to the metallurgical manufacture.

The plan of the technological line of metallurgical briquette production plants with different productivity is shown on the poster 5.

The area of application of briquettes is shown on the poster 2:

-   blast-furnace production;

-   steelmaking industry, which is divided into converter industry, open-hearth industry, and electric furnace steelmaking;

-   ferroalloy industry;

-   foundry manufacture, which is divided into cupola-furnace and electric arc oven.

With the metallurgists of some plants from Russia and abroad, we have defined the area of briquette application and developed its composition. In 2001 were published a lot of technical specifications, such as - 0303-002-55978394-2001, - 0780-001-55978394-2001.

The types of briquette and their metallurgical value are shown on the poster 4.

Blast-furnace production:

- - briquette, as a substitute of iron-containing raw material (agglomerate, pellets, metal admixture), blast-furnace coke and flux;

- - briquette for washing of the well of blast furnaces (F 40-60 %);

- - briquette with manganese and silicium for smelting of special iron grades;

- - briquette for growing of the wall accretion of the well of blast furnaces. Steelmaking manufacture:

-C - briquette as a substitute of iron, carbonic scrap, carbonic additives and flux;

- - briquette with deoxidizing alloy additions (Mn, Si, l etc.);

- - briquette for scorification and temperature control in the steel furnace;

- - a composite briquette with alloy additions and wood charcoal as a regenerator.

Ferroalloy manufacture:

- - a composite briquette for production of ferroalloys (with FSi, F, FS, , Sin, Fn, S, l and carbon in the form of coke breeze and dag, powdered wood charcoal). Foundry manufacture at the machine works:

- - a special briquette with alloy additions and deoxidizing additives;

- - a composite iron-containing briquette as a substitute of pig iron and waste iron when obtaining hot metal for casts;

- - a composite briquette with wood charcoal as a regenerator.

We think that the metallurgical briquette that we offer is a natural development of the earlier proposed mix material, which is called synthicom.

Thereby Tula has confirmed once again that it is called the native land of the Russian iron and steel industry.

In 2002 the first blast-furnace plant, which was constructed on the river Tuliza by Vinius and Makena, will celebrate the 370th anniversary.

Briquette has a number of advantages as compared with synthicom:

-   briquette is much cheaper;

-   briquette is a mix material not only for steelmaking industry, but also for blast-furnace production and ferroalloy industry;

-   the content of carbon that is so necessary for metallurgists, is much higher in briquette, than in synthicom;

-   the technology of cold briquetting allows to ensure the stability of weight and the uniformity of the chemical composition in each briquette.

The research of the metallurgical characteristics of briquette was done in laboratories on the samples that had been smelted in the resistance furnace.

The conducted mineral-graphic efforts are shown on the poster 7, where you can see the reductive processes in the iron-carbon briquette with the help of the optical microscope.

In the picture the initial composition of briquette is shown:

68 % - oxide scale;

20 % - coking dust;

12 % - the binder;

F (total) - 48 %, C - 16 %

compression strength -130 kg / 3;

accessible porosity - 16 %;

density - 2,1 kg / 3

The light fission-fragment flakes of oxide scale with dark round slices of coke breeze and grey straps and impregnations of the binder (cement stone) between them.

In the picture 2 the shear of the briquette that was heated up to t - 850900C is shown (the beginning of the softening).

The formation of metal iron in the form of impregnations of a light colour in wustite grains inside the bits of the oxide scale, the shape of the bits of the oxide scale is saved.

In the picture 3 the shear of the briquette that was heated up to t - 9001100 is shown.

The junction of the impregnations of metal iron into a porous jaw of a light grey colour.

In the picture 4 the shear of the briquette that was heated up to t - 11001200 is shown.

The integration of the segments of the reduced iron and its saturation with carbon in the form of the hypereutectoid steel with a light cement net at the edges of grains.

In the picture 5 the shear of the briquette that was heated up to t - 1400C is shown (the end of the softening).

The carbonization of the metal bits up to a condition of pig-iron.

In the picture 6 the final composition of the briquette is shown:

the microsection from fractionally disrupted cake of a light brown colour with shiny formations of different shapes of the recovered metal iron.

Firing temperature - 1400 ;

the degree of metallization - 95 %;

F (total) - 61 %, F (met) - 58 %, /Si2 = 1,7.

From the above-stated we have come to the following conclusions:

1. The carbon of the coal-containing component of the briquette completely reduces the oxides of iron up to metal iron with its consequent carbonization.

2. The finished product of the sintering of the iron-carbon briquette at the temperature of the end of the softening is pig-iron.

3. The accessible porosity, density and compression strength of the carbonic briquette are the regulators of mix design for the metallurgical refining.

In the same way we can suppose that every iron-carbon briquette when the heat energy is placed form outside can be called a mini blast-furnace.

We have developed and counted economically sound prices of metallurgical briquettes; though for each manufacture depending on the production conditions, outputs and volumes of usage in the refining these prices will vary.

For example, for the blast furnace with the volume from 1000 m3 up to 2000 m3 the calculations have been made according to the traditional method and are shown in table 1 and 2 with the usage of iron-carbon briquettes for the manufacture of foundry pig-iron and without them.

The results of calculations of the usage of briquette - 52/19 in the blast-furnace are shown on the poster 8.

 

Table 1.

The formation of the price of the briquette.

 

Briquette composition

Contents, %

Price per ton, rubles

The cost, rubles

Roll scale

30

300

90,0

Sludge of sintering plants

15

25

3,7

Fine metal additive

25

915

228,7

Coke dust

20

800

160,0

Binder

10

900

90,0

Total

100

 

572,4

Refining costs, rubles

 

 

300,0

The price of briquette

 

 

872,4

The chemical composition of the briquette

Fe(total) =52,14 %; =19,37 %; =8,17 %; SiO2 =12.56 % MgO=0,3

 

 

Table 2

The comparative calculation of the net price of foundry pig-iron with the traditional mix material (basic) and with the usage of briquettes (experimental).

The index name

Basic, kg/t

The cost, rubles

Experi-mental, kg/t

The cost, rubles

The price, rubles/t

coke

630

945

572

858

1500,00

agglomerate

700

339,5

785

380,7

485,00

blast furnace pellets

585

288,5

580

253,6

488,98

fine metal additive

271

247,9

--

--

914,89

iron-carbon briquette

--

--

271

236,4

872,4

 

blast-furnace ore

72

11,5

72

11,5

159,86

manganese ore

23

76,4

23

76,4

3322,00

Net cost of iron

 

1908,8

 

1816,6

-92,2

The specified parameters in the calculation

Si, %

2,0

 

2,0

 

 

CaO/Sio2

0,99

 

0,99

 

 

RO/Sio2

1,12

 

1,12

 

 

Fluid-dissolved iron, kg (without metal additives)

 

 

 

1380

 

 

 

1460

 

 

Fe (met), calculated %

 

54,87

 

 

55,03

 

 

 

 

The predicted and expected effect from the usage of the iron-carbon briquette:

- the cost reduction of pig-iron on 92,2 rubles/t;

-   lowering of the coke rate on 58 kg /t;

-   the increase of productivity at 4,6 %;

 

owing to:

-   the substitution of a part of metallurgical coke by coke breeze of the iron-carbon containing briquette;

-   implication of agglomerate finely cut cheap iron-containing materials into the blast furnace mix material and returning pig-iron swaftagglomerated.

-   a quick pay-back of the vibropress equipment: from 2 up to 8 months.

 

Certainly we have only started and the capacities of briquette can be wider than we expect. We understood it after the Seventh International Congress of Blast-furnace Men, that was held in Moscow and Cherepovez from 9 to 12 September.

Today we are offered the opportunity to inform metallurgists of our project and we hope that as a result of cooperation this trend will occupy a worthwhile place in the Russian metallurgy.

 

Let us show you the averaged calculation of the briquette production effectiveness (briquette - 45/19), that you see on the poster 9.

 

 

 

 

 

 

 

 

 

Table 3

The calculation of the briquette production effectiveness

Pig-iron

Briquette - 45/19

 

1. The content of the components (% by mass)

Fe 95,0

Fe 45,0 C 19,0

C 4,5

CaO 9,2 MgO 0,7

Mn, Si, S, P etc 0,5

SiO2, P2O4, S and others 26,1

2. The market value for a ton of the material, rubles

3100-00

Scale 300-00 (247-50)*

 

Coke breeze 800-00 (220-00)*

 

Binder 600-00 (66-00)*

 

Costs for a ton of briquette 200

 

Total 727-50

 

( )*the cost of the material in briquette

3. The calculation of the one ton cost by iron, rubles

2945-00

1534-00

4. Efficiency factor by carbon, standard unit

1,0

1,01,5

 

From the poster 9 we can see that the actual cost of the briquette is much lower its metallurgical value (2945rubles - 1534 rubles = 1411 rubles) and the effectiveness of its usage in recalculation for a ton of iron is 1411 rubles.

The cost efficiency of the briquette usage in the blast-furnace and steel-making production will be much higher than mentioned here, as we had to buy industrial waste and transport it to the place of briquetting. At any plant (or near) there are accumulated over the decades reserves of raw material at a minimal cost.

When using pig-iron for steel smelting in the arc electric furnace 50 kg of iron is turned into liquid melt (without the waste).

When using - 45/19 the most part of carbon will be needed for reduction of ferric oxides. The residual content of carbon, turning into melt, will be 1,52,5% (according to the results of the meltings in the laboratory oven). The actual residual content of carbon in the melt is much higher than the results of the experimental-industrial melts in the open-hearth ovens at Taganrogsky Metallurgical Plant Public Corporation and BMZ Public Corporation.

We should note that we did not consider the detrimental effect of the additives of briquette, silicon dioxide, sulphur dioxide and phosphor dioxide, presence of which is determined by the chemical composition of briquette components.

Nevertheless, from the poster 9 we can see that the economical practicability of the briquette production and usage is obvious and can reach 100%.

Every plant has the opportunity to evaluate its own effectiveness based on the traditionally existing price level and level of costs.

Meltings with iron-carbon briquette were conducted in open-hearth ovens at Liepaias Metallurgs Cooperative Association (Latvia), Taganrogsky Metallurgical Plant Public Corporation and BMZ Public Corporation. The results of the meltings are expounded in the report of NPMP Intermet-Service Ltd, Tulit Public Corporation together with BMZ Public Corporation under the title The results of the iron-carbon briquette usage in the mix material of the open-hearth ovens, working as scrap process .

The sixth chapter (Water purification and waste utilization) of the book Engineering protection of the environment is devoted to the developed by us technology. This book was written by composite authors, edited by U.A.Birman, N.G.Vurdova (publishing house ASB, 2002).

This book is oriented for engineers, technicians and scientists of the developers, operational and research organizations and is recommended as a manual for institutions of higher education.

The main conclusion of the sixth chapter is that ironwork have all the necessary background to become the core industry of utilization of all kind of waste within the realization of the conception of the global recycling of the man-caused materials.

It is important to underline that our technology was worked out within the priority lines of the Ecological doctrine of the Russian Federation, approved by the decree of the Government of the Russian Federation of the 31st of August 2001 1225-p.

This is a special, but a very actual theme for discussion

And finally, summing up the report I would like to tell you the following information (poster 10 and 11).

Cooperation with Gevit Ltd and Ecomashgeo Ltd

 

the enterprises that have accumulated invaluable theoretical and practical experience

the enterprises that cover a wide geography of introduction of advanced practical experience

the enterprises-patentees in the sphere of waste utilization and obtaining from it highly remunerative metallurgical raw material

will give you the opportunity

-   to define the verges and volumes of man-caused waste deposits, situated in your region

-   to adjust the technology of the briquette production to a concrete plant

-   to make the experimental industrial batches of the metallurgical raw materials for balance meltings with the purpose of getting a maximum economical effect at your plant

-   to obtain, install, set up and adjust the machinery

-   to offer a guarantee and service accompaniment of the processes of metallurgical briquette production

-   to offer a further service expansion in the sphere of developing of the briquette technology in the metallurgical manufacture.

 

 

 

List of the used literature:

1. B.M.Ravich Briquetting in colour and iron and steel industry. . "Metallurgy", 1975.

2.L.A.Lurie Briquetting in metallurgy. . "Metallurgy",1963.

3. V.P.Bulgakov, G.V.Bulgakov The research of the mineralogical content of the scale-carbonic briquettes during the process of reduction. . "Iron and steel industry", 1998 7

4. The report by I.M.Mischenko Utilization of the agglomerate carbon-containing metallurgical dust, "Pig iron production", 1998.

5. O.V.Yuzov, V.A.Isaev The analysis of the expenditure of the base resources in iron and steel industry of Russia. "Steel" 10, 1999.

6. V.S. Lisin The tendencies of re-structuring of iron and steel industry. "Steel" 10, 1999.

7. Patent for invention 2183679. Briquette for metallurgy industry, briquette for furnace washing of the blast furnace and the method of briquette production.

8. Engineering protection of the environment edited by U.A.Birman, N.G.Vurdova publishing house ASB, 2002, 296 p. with illustrations.

Contact info:
tel./fax: +7 (0872) 45-81-16, cell. +7 (910) 941-78-05, Vasiliy Kotenev
E-mail: mashgeo@tula.net briket@briket.ru

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