CN1092242C - Method for smelting ferrocolumbium by two-step electric furnace reduction - Google Patents

Abstract

By using Nb₂O₅The method for producing ferrocolumbium from 1-8% low-grade complex niobium concentrate mainly comprises the steps of adding coke powder and an organic binder into the niobium concentrate, mixing and rolling, briquetting and drying to prepare an internal carbon pellet. Pellets are suitably placed in an electric arc furnaceUnder the pH value and the temperature, selective pre-reduction, iron removal, phosphorus removal, sulfur removal and niobium enrichment are carried out to obtain niobium-enriched slag and phosphorus-containing semisteel. And adding the mixed aluminothermic reducer into the niobium-rich slag in a secondary electric arc furnace for deep reduction to obtain the qualified ferrocolumbium. The total niobium yield from the niobium concentrate to the niobium-iron alloy reaches 73-92%; and 2-8 tons of semisteel and 3.5-8 tons of poor niobium slag containing 6-8% of rare earth can be produced as a byproduct for producing 1 ton of ferrocolumbium, and a new way is opened for extracting niobium.

Description

The method of smelting ferro-niobium by two-step electric furnace reduction

The present invention relates to field of metallurgy and chemical engineering and handle the method for low-grade niobium concentrate.

One of representative method of handling this material is " blast furnace-converter-electric furnace-eaf process flow process " (an abbreviation blast furnace-converter-double electrical furnace process), its principle technology is to contain the iron ore of niobium and rare earth element or to contain the niobium open hearth slag under the condition of proper acidity or alkalinity, adds coke for smelting and get the rich slag of niobium-bearing hot metal and rare earth (1350 ± 10) ℃ in blast furnace; Niobium-bearing hot metal is delivered to blowing under 1360～1420 ℃ in the converter, get rich niobium slag and phosphorous molten steel; Send rich niobium slag to electric furnace again and add coke for smelting, further phosphorus falls in deferrization, gets low-phosphorous low iron niobium slag.Allocate this slag into suitable coke, send into another electric furnace and carry out further retailoring, obtain ferrocolumbium and [see that Li Shang calls on and wait chief editor's " niobium development of resources utilisation technology " P.114～135, P117～195 metallurgical industry press.Beijing in 1992.Ferroniobium?Productionat?CRMM，Brazil，SteelTimes，Vol，209，No.4，P?187，(1981)]。The technical process of this method is oversize, needs blast furnace, converter and two electric furnaces, and facility investment is big, and factory building takes up an area of many, and the niobium yield is very low, the energy consumption height.

The objective of the invention is to study a kind of is raw material to handle low-grade niobium concentrate, produces the novel method of ferro-niobium, makes it advanced technology, and flow process is short, the metal recovery rate height, and production cost is low, the fixed capital less investment.

Basic craft course of the present invention is seen shown in the accompanying drawing (two step electric furnace process are smelted the ferro-niobium schema), comprise the preparation cooled agglomerated pellet, one time electrosmelting produces phosphorous half steel and rich niobium slag, with rich niobium slag is that raw material carries out the secondary electrosmelting, under the effect of aluminiferous metals reductive agent, produce three operations such as ferrocolumbium and poor Biobium rare-earth slag.

Joining the charcoal cooled agglomerated pellet in the preparation is the first road master operation of present method.Wherein, this operation comprises batching, batch mixing, pressure group and dry four steps again.Pelletizing mainly is made up of 4 kinds of components, that is: the niobium concentrate---contain Nb ₂O ₅1～8%, total iron 37～55%, grade accounts for 80% for-150 orders; The coke powder---contain fixed carbon 〉=80%, grade accounts for 80% for-80 orders; Binding agent for the natural organic-compound colloid, contains functional groups such as carboxyl; Additive---ground silica or lime are used to adjust the slag potential of hydrogen.The basic proportioning of these components is: with the niobium concentrate is 100 parts, and then coke is 11～20 parts (deciding according to the iron-holder in the ore deposit), 2～8 parts of binding agents; Will rationally mix the above-mentioned furnace charge that has prepared, equipment used is wheeled mixed rolling machine or cement plaster blender for building, and the operating time is 10～60 minutes, and will keep the skin wet to material in time, and to make its water content be 8～15%.Mixed material is pressed group, and equipment used is Domestic eggette machine or garden dish nodulizer.The roller of ball press directly is 300mm, and pressure is 80Kg/cm ², form the group of giving birth to.The group of giving birth to that suppresses is removed the water yield to pelletizing water content under 200～350 ℃ of temperature be about 1%, is the group of doing.In addition, for improving the performance of binding agent, need add a certain amount of metal ion, make it to generate salt, its metal ion comprises Ca ²⁺, Mg ²⁺, Cu ²⁺Deng divalent ion, K ⁺, Na ⁺, NH ₄ ⁺Deng monovalent ion and Fe ³⁺Deng polyvalent ion.It has certain reducing power, but its aerial oxidizing fire temperature＞600 ℃.

The second road master operation of this method is the electrosmelting of joining the charcoal pelletizing.The fundamental procedure of this technology and concrete processing condition are: niobium concentrate carbon-burdened pellet is placed carry out the prereduction melting in the DC-ore-heating electric arc furnace.Its smelting temperature is 1350～1480 ℃, and the reaction times is 50～180 minutes, and under this processing condition, impurity such as the iron in the furnace charge, phosphorus, sulphur are reduced by selectivity, form phosphorous half steel, and niobium and rare earth metal are not reduced, and form rich niobium slag.Melt mat difference of specific gravity and phase-splitting makes half steel separate with rich niobium slag.

The 3rd road master operation of present method is rich niobium slag retailoring ferro-niobium.This operation equipment used also is an electric furnace, rich niobium slag is carried out drastic reduction with aluminum mixture thermal reduction agent, its aluminum mixture thermal reduction agent is siliceous, aluminium, iron, add-on is 1.1～1.2 times of theoretical amount, then in electric arc furnace＞carry out drastic reduction under 1500 ℃～1600 ℃, reaction times is 120～200 minutes, gets ferro-niobium product and poor Biobium rare-earth slag.

The present invention has following positive effect.The first, owing to adopted rigorous batching, batch mixing, the measure of pressure group, the furnace charge of subsequent handling is mixed, good permeability, stable performance, bigger than resistance, the softening temperature height, the working of a furnace is stable, energy efficient.And,, not only improved pellet strength, and do not brought detrimental impurity into owing to adopted organic binder bond.Second, by the electric furnace prereduction melting first time, not only realized the enrichment of niobium and separated with impurity such as iron, phosphorus, sulphur, and directly obtained phosphorous half steel, can be used as extraordinary raw materials such as producing train wheel medium phosphor cast iron brake shoe and mechanical roll, thereby reduce whole ferro-niobium smelting cost (output capacity of half steel is 2～8 times of its ferro-niobium amount).Meanwhile, owing to adopted the composition metal reductive agent, its reducing power is strong during than general reduction with carbon, and the niobium reduction is (can reach 77～93%) thoroughly; The 3rd, by the electric stove metal reduction of second step, realized separating of niobium and rare earth element, obtained the rich slag of the second best in quality ferro-niobium product and rare earth, contain niobium in its ferro-niobium and reach 10～40%, Nb/P=15～33, the rate of recovery of whole process niobium reaches 82～92%, and the contained rare earth of the rich slag of the rare earth element of output reaches 6～8%.

Accompanying drawing is that two step electric furnace process are smelted the ferro-niobium schema.

In making, description of drawings: 1-joins the solid pelletizing of the cold ball of carbon; An electric furnace reduction melting of 2-; The melting of 3-secondary electric furnace reduction.

Embodiment:

Raw materials used is grade niobium concentrate in the dolomite 2# ore body of packet header, and main chemical compositions is (%): Nb ₂O ₅7.55, T _Fe40.19, FeO5.86, CaO5.20, SiO ₂8.00, MgO4.71, Al ₂O ₃3.99, K ₂O0.75, Na ₂O0.24, granularity accounts for 85% for-120 orders.The ground silica that adds contains SiO ₂97.5%, granularity accounts for 87% for-120 orders; It is 2.05% that institute adds the coke powder fugitive constituent, and ash content is 17.74%, fixed carbon 80.21%; Material formula is (by weight): get 100 parts in niobium concentrate, 13 parts of coke powders, 1.5 parts of ground silicas, binding agent A-1 ^#4 parts, control moisture content is after 12% 4 kind of material mixes 10 minutes with φ 700mm cement plaster blender for building, to press group with the Domestic eggette machine again, and pressure is 80Kg/cm ², the agglomerate yardstick is 40 * 36 * 23 (mm), and the dropping strength that gained is given birth to group is 4.1 times/0.5 meter, and ultimate compression strength is 5.8Kg/.Give birth to group's baking in 250～380 ℃ of scopes and be the group of doing to moisture about 1.3%.Its ultimate compression strength is 61.5Kg/, and dropping strength is 6.3 times/meter, and 800 ℃ of hot resistance to compressions heating down 30 minutes be that 42.7Kg/ is individual, burst temperature＞1200 ℃.Co-processing niobium concentrate is 1.097 tons in the example, must join 1.31 tons of carbon-containing.

Dividing 8 batches of input power with above-mentioned pelletizing is in single motor DC electric arc furnace of 200KVA, under 1420～1480 ℃, handles through about 180 minutes melting, and the average assay (%) of the rich niobium slag that produces is Nb ₂O ₅15.1, P1.035, T _Fe6.37, SiO ₂22.54, Al ₂O ₃8.07, CaO22.46, MgO9.02; The output capacity of phosphorous half steel is 36.4%, and its performance is tough and tensile, can make train brake shoe foundry goods.The niobium smelting recovery of this technology is 98.32%, and the deferrization rate is 91.82%, dephosphorization rate 48%, desulfurization degree 76%.The rich niobium slag of electric furnace gained is sent in the direct current electric arc furnace, and batching is regulated the slag type, under＞1500 ℃, reduces with silico-calcium and ferrosilicoaluminum mixing reductive agent, and add-on is 1.1～1.2 times of theoretical amount.Got water content Nb30.8%, P1.66%, S0.07%, the ferrocolumbium of Al0.08%, its Nb/P=18.55 in 30 minutes through reacting.With respect to rich niobium slag, the ferro-niobium productive rate is 88.12%.To ferrocolumbium, the total yield of niobium is 86.62% from the niobium concentrate; 1 ton of ferro-niobium of every product, but 2.51 tons of half steels of by-product and 3.5 tons of the poor niobium slags that contains rare earth 7%.

Claims (2)

1, a kind of method of two-step electric furnace reduction melting ferro-niobium, it is characterized in that: it is made by the niobium concentrate and joins carbon-containing, an electric furnace selectivity prereduction melting is carried out rare earth slag and is separated with half steel, and the secondary electrosmelting carries out drastic reduction melting ferro-niobium three road master operations with rich niobium slag with aluminum mixture thermal reduction agent and forms; Niobium concentrate main component content range is Nb ₂O ₅1～8%, T _Fe37～55%, grade accounts for 80% for-150 orders, add with 100 parts with above-mentioned niobium fine ore and to contain fixed carbon 〉=80%, grade accounts for 11～20 parts of 80% coke powders for-80 orders, the basic proportioning that binding agent is 2～8 parts and be used to adjust the additive formulations of slag potential of hydrogen, mix the group of pressure and under 200 °～350 ℃ temperature dry water content be about 1% carbon-burdened pellet; Will in join the carbon cooled agglomerated pellet and place and carry out the prereduction melting in the electric arc, its smelting temperature is 1350 °～1480 ℃, the reaction times is 50～180 minutes, realizes deferrization, dephosphorization, sulphur removal, rich niobium slag and contain the niobium half steel; Drastic reduction is carried out in the aluminum mixture thermal reduction agent that rich niobium slag adds 1.1～1.2 times of theoretical amount in electric arc furnace, 1500 °～1600 ℃ of temperature of reaction in 120～200 minutes reaction times, get ferro-niobium product and poor Biobium rare-earth slag.

2, the method for two-step electric furnace reduction melting ferro-niobium according to claim 1, it is characterized in that: binding agent is that a kind of proportion is 1.3～1.5 natural macromolecular compound, and, making it to generate salt through salify preparation with addition of metal ion, its metal ion comprises Ca ²⁺, Mg ²⁺, Cu ²⁺, K ⁺, Na ⁺And Fe ³⁺Deng polyvalent ion.

Images