1. 1 iron ore mining

1. 1. 1 iron ore mining

The main mining methods of iron ore are open pit mining, underground mining and liquid mining.

1. 1.2 iron ore enrichment

The enrichment process of iron ore includes crushing, grinding, screening, classification and separation.

1. 1.3 iron ore powder briquetting

The methods of iron ore powder briquetting are mainly divided into sintering method and pelletizing method.

1.2 blast furnace ironmaking [1]

1.2. 1 blast furnace ironmaking process

A) Iron ore, coke and flux (limestone) for slagging are charged into the top of the furnace.

B) Preheated air is blown along the circumference of the furnace from the tuyere located at the lower part of the furnace.

C) Carbon in coke (also injected with auxiliary fuels such as pulverized coal, heavy oil and natural gas). ) and the oxygen blown into the air are burned at high temperature to generate carbon monoxide and hydrogen, and the oxygen in the iron ore is removed during the rising process in the furnace, thereby reducing to obtain iron.

D) molten iron is discharged from the taphole.

E) Unreduced impurities in iron ore combine with flux such as limestone to generate slag, which is discharged from the slag outlet.

F) The generated gas is led out from the top of the furnace and used as fuel for hot blast stoves, heating furnaces, coke ovens and boilers after dust removal.

1.2.2 characteristics of blast furnace ironmaking

(1) Blast furnace smelting is to complete all kinds of complex chemical reactions and physical changes in the process of reverse movement of charge and airflow, and the reducing atmosphere is mainly in the furnace.

(2) The blast furnace is a closed container. In addition to charging, tapping, slagging and gas, the operator can not directly observe the reaction process, but can only indirectly observe the situation in the furnace with the help of instruments.

(3) Blast furnace is a continuous large-scale high-temperature production process with high mechanization and automation.

1.3 ferroalloy production

Use 1.3. 1 ferroalloy.

① Alloy additive ② Deoxidizer ③ Inoculant.

1.3.2 production method

The main production methods of ferroalloy are carbon reduction process (blast furnace and electric furnace), metal thermal reduction and electrolysis.

1.4 steelmaking raw materials

Steelmaking raw materials can be divided into metal and nonmetal.

1.4. 1 metal material

Metal materials mainly refer to molten iron (or pig iron), scrap steel and ferroalloy.

1.4.2 nonmetallic materials

Non-metallic materials mainly refer to slagging materials, oxidants and coolants.

1.5 basic tasks of steelmaking

A) Decarburization and adjustment of its content to a certain range.

B) Impurities removal, mainly including dephosphorization (cold embrittlement), desulfurization (hot embrittlement), deoxidation, and removal of gases (hydrogen and nitrogen) and nonmetallic inclusions (oxides, sulfides, phosphides, nitrides, etc.). )

C) adjusting the composition and temperature of molten steel

D) casting molten steel into high-quality steel ingots or billets.

1.6 converter and open hearth steelmaking

Converter steelmaking methods mainly include bottom blowing acid converter steelmaking method, alkaline converter steelmaking method, side blowing acid side blowing converter steelmaking method, oxygen top blowing converter steelmaking method (LD method), oxygen bottom blowing converter steelmaking method and top-bottom combined blowing converter steelmaking method.

1.6. 1 Basic principle of converter steelmaking method

It relies on the exothermic oxidation reaction between air or oxygen blown into the molten pool and various elements in pig iron water without the help of external energy to heat the molten steel to the tapping temperature (1600℃ or higher).

1.6.2 oxygen top-blown converter steelmaking method

A converter steelmaking method using pure oxygen to blow molten iron from the top of the converter to form steel. Since it was put into industrial production in the early 1950s, it has been rapidly popularized all over the world, gradually replacing the air converter method and the open hearth steelmaking method, and has become the main method of modern steelmaking.

Advantages of 1.6.3 LD method

A) Fast blowing speed and high productivity;

B) Variety and good quality;

C) Less consumption of raw materials, high thermal efficiency and low cost;

D) Less capital investment and faster construction;

E) Easy to match with continuous cast steel.

In view of the above advantages, oxygen top-blown converter steelmaking has now become the main steelmaking method.

1.6.4 characteristics of open hearth steelmaking

The heat supplied by the outside is due to the huge furnace body, long smelting time, large heat loss on the furnace wall and high temperature exhaust gas taking away heat. In addition to the heat generated by the oxidation of various elements in iron and steel raw materials, it is necessary to supply fuel from the outside and use preheated air to burn the fuel to maintain the heat required for steelmaking.

1.6.5 raw materials for open hearth steelmaking

(1) iron and steel materials such as pig iron or molten iron and scrap steel;

(2) Oxidizers such as iron ore, industrial pure oxygen and artificial rich ore;

③ Slagging agents, such as lime (or limestone), fluorite, bauxite, etc.

(4) deoxidizer and alloy additive.

1.6.6 steps of open hearth steelmaking

The process of open hearth steelmaking is usually divided into several steps, such as reheating, charging (iron ore, lime and scrap steel), heating, adding molten iron, melting, refining, deoxidation and tapping.

1.6.7 Advantages of open hearth steelmaking

① A large amount of scrap steel can be used, and the ratio of pig iron to scrap steel is flexible;

(2) The requirements for the composition of molten iron are not as strict as converter, and ordinary pig iron that converter can't use can be used;

③ More kinds of steel can be smelted than converter, and the quality is better.

1.7 EAF smelting

1.7. 1 Advantages of electric arc furnace smelting

A) high thermal efficiency, reaching more than 65%

B) the temperature is easy to control and adjust.

C) The atmosphere in the furnace is controllable, which is beneficial to dephosphorization, desulfurization and deoxidation.

D) The inclusions in steel are relatively low.

E) high alloy yield.

F) All scrap steel can be smelted, and some molten iron can also be mixed.

G) Simple equipment, less land occupation, less investment and quick plant construction.

However, at present, the quantity of scrap steel in China is small and the price is high, and the nitrogen and hydrogen content in steel is higher than that in converter due to arc dissociation.

1.8 external refining

1.8. 1 refining principle

Vacuum degassing, vacuum deoxidation, inert gas treatment and molten steel stirring.

1.8.2 Main technological methods of external refining

A) Submerged arc heating ladle refining method (LF method, developed in Japan 197 1 year).

B) Vacuum oxygen blowing decarburization refining method (VOD method, developed by West Germany 1965)

C) argon-oxygen furnace decarburization refining method (AOD method, developed by USA 1968)

1.8.3 external refining has the same process characteristics as * * *

① Choose an ideal refining atmosphere, usually vacuum, inert atmosphere or reducing atmosphere.

② The molten steel can be stirred by electromagnetic induction, inert gas flow or mechanical method.

(3) molten steel heating, usually using arc heating, submerged arc heating, plasma heating or increasing chemical heat in the refining process.

Casting of 1.9 steel

Steel production includes steelmaking and casting.

1.9. 1 casting operation

The qualified molten steel is cast into a billet (or ingot) with a certain shape, size and unit weight suitable for rolling or forging.

1.9.2 Two casting methods of molten steel

A) Ingot die casting, also known as die casting process, the finished product is ingot.

B) It is continuous casting steel, also called continuous casting process, and the product is continuous casting billet.

1.9.3 casting method

Ingots can be divided into upper casting method and lower casting method.

1.9.4 type of continuous casting machine

At present, the commonly used continuous casting equipment is arc continuous casting machine. Vertical type, vertical bending type and inclined type are the products of the development process, among which vertical type is still used in a few factories, while horizontal type, rotary wheel type and centrifugal rotary continuous casting machine are still in the experimental or small-scale production stage.

1. 10 metal plastic working

1. 10. 1 classification

According to whether work hardening is completely eliminated during plastic working, it can be divided into hot working and cold working.

1. 10.2 Classification of machining force types

① Direct compression, such as forging, extrusion and rolling;

(2) Indirect compression, such as wire drawing, tube drawing and deep drawing of metal plates;

③ Tension, such as wire drawing;

(4) When bending, apply bending moment, such as cold bending of metal;

(5) shearing, that is, applying shearing to shape the metal, such as punching and shearing.

1. 10.3 working characteristics of metallic plastics

Metal plastic working plays an important role in the production of modern metallurgical industry. Compared with metal cutting, plastic processing has the following advantages:

(1) In principle, there is no chip and less metal loss;

(2) improving the structure and performance of the material while obtaining the required shape, so that the finished product can be directly used or easily processed;

③ Suitable for specialized mass production.

The main disadvantages are:

① Some brittle materials and products with complex shapes are not suitable for plastic processing;

② Specialized production needs special equipment and tools.

1. 1 1 metal heat treatment

Metal heat treatment methods include annealing, normalizing, quenching, tempering and tempering.