Makhortova Yulia

Theme urgency

The offered for introduction technological methods are directed to steel production on resources and power savings, and also on diminishing of harmful emissions of production. They will allow to lower expenses of fuel resources, to improve and accelerate fusion process, to reduce ejections of a dust and toxic connections. It will lead to lowering of the cost price of production and lowering of harmful effect on surrounding environment.[1]

Purpose and work problems

Work purposes :
— diminishing energy cost steel production;
— working out resources saving technologies;
— diminishing the harmful effects of electric production on the environment. Problems:
— search and improvement of energy-saving technologies;
— search and improvement resource-saving technologies.

Novelty of work

Novelty of work consists that modern technologies which allow to reach the planned purposes and problems of this work are offered for introduction in steel production.

Practical importance of results

Result of the given work — working out of technological methods for introduction in the conditions of steel production. Use of these methods will allow the enterprise to organise more effective production of a steel, having ensured the minimum negative effect of production on environment, will allow to lower possible ecological payments for emissions, will lower product cost at the expense of decrease in power inputs and reduction of ecological payments, will allow to increase competitiveness of production and to increase production export capacities. Results of the given work can be applied to conditions of any factory.[2]

Basic researches and results

Steel production is one of the productions which are throwing out a considerable quantity of a dust of other fouling substances. The size of these emissions depends on applied raw materials, a technological mode of fusion and a method of tap of gases from the furnace. The exit of technological gases from electric-arc furnace is advanced by carbon combustion and electrodes. Quantity of departing gases equally 40 — 150 m³/ch per 1 т . The physical and chemical processes proceeding in electric furnaces at melt of various marks of steels are various, they advance structure of harmful emissions.[3]

Dust emissions.The dust is formed as a result of evaporation of metal around action of the electric arches which steams are condensed and interact with oxygen and nitrogen present in working space of the furnace.

In fusion pure and large-sized the dust small amount is formed. In boiling emissions reach peak figures as a result of action of oxygen streams and active boiling of metal, in operational development emissions decrease to a minimum. Dust carrying out constitutes 10 kg/t of the steel melted without a purge by oxygen, and 20 kg/t of a steel with a purge. In first half of fusion about 75 % of all dust are allocated.

The dust which is emitted electric-arc furnace, consists mainly of iron oxides. During melting the total number of iron oxide is about 80%, during the boil is about 62%, during the fine-tuning is about 53%.[4]

Table 1 — Chemical compound of dust of electric-arc furnance

Composition	Content, %
	by K. Gutman	by V.B. Uelis
Fe2O3	19	37,2
Cr2O3	1	0,13
NiO	0	0,02
MnO2	4	4,2
SiO2	14	2,98
Al2O3	2	0,41
CaO	22	5,17
MgO	38	2,45
Losses	0	3,6
PbO	0	3,92
CuO	0	0,4
ZnO	0	35,5
SO3	0	1,54
N2O — K2O	—	1,6

Emissions. High temperatures and the effect of electric arc furnaces in the working space influence on the formation of carbon monoxide, nitrogen oxides and sulfur compounds, cyanides and fluorides, which are emitted from the furnace with the gases.

Off gases are explosive. Composition of gas %: CO — 15-25 %, H₂ — 0,5-3,5; CO₂ — 5-10; N₂ — 61-70; O₂ — 3,5-10.

Table 2 – Chemical compound of gases of electric-arc furnance

Compounds	Composition, mg/m3	Emissions, g/t d'acier
NOx	550	270
SOx	5	1,6
CO	13500	1350
Cianids	60	28,4
Ftorids	1,5	5,6
CH4	0,9	no info
Benzopiren (mkm/m3)	0,09	no info

Improving the environmental performance of production.

1. It’s good to support a constant pressure inside equal to the outside air pressure.

2. Emissions of dust can be reduced by using gas-oxygen torch and tuyere of special construction, which may intensify the process of steel smelting.

3. The introduction of inert gas to reduce the number of large particles of dust in 2 — 3 times and the technology of melting does not change.

4. Emissions reduction can be realized by optimizing the way of oxygen feed into the furnace and bring of extra heat in the workspace.

5. It’s necessary to reduce the temperature of the metal in the reaction zone for diminishing dust emissions.

6. Addition to the oxygen blowing of air can substantially reduce the intensity of dust formation.

7. The process of dust formation can be reduced by adding in oxygen stream of various powdered materials.

8. Diminishing dust emissions can be achieved by changing of the construction of electric arc furnace.

Toxic emissions and their diminishing

Dioxins are one of the most toxic compounds. Electric-arc furnaces emit about 0,01 — 1,3 ng/m³ of "toxic equivalent". Dioxins decompose at high temperatures more than (1200 °C). However, they re-formed at a temperature of 200 - 600 °C.[5]

Drawing 1 — Influence of the temperature of gases to the concentration on dioxins

Conclusion

It’s necessary to create energy-saving and low-dust technologies for diminishing of emissions into the atmosphere. Rational using of natural resources diminishes their consumption and by recycling of dust diminishes the influence of electric production on the environment.

Liste of the used literature

1. Андоньев С. М, Зайцев Ю. С, Филипьев О. В. Пылегазовые выбросы предприятий черной металлургии. — Харьков — 1998. — 246с

2. Афонин С. З. Сталеплавильное производство России и конкурентоспособность металлопродукции // Электрометаллургия. 2003. № 1. С. 2 — 5.

3. Вагин Г. Я., Лоскутов А. Б., Шалаев С. А. Основные направления экономии энергии на металлургических предприятиях // Промышленная энергетика. 1995. № 9. С. 12—15.

4. К.Л. Клайн Высокопроизводительная работа электродуговой печи с малыми выбросами на заводе BSW // Электрометаллургия. — 2000, №7.— с.23—30.

5. Вишкарев А. Ф. Снижение пылевыбросов в атмосферу при выплавке стали в электродуговых печах. // Новости черной металлургии за рубежом. — 2003. — № 2. — с. 68 — 69.

The note: At present work is in a working out stage. End is planned for the beginning of December, 2009.

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