RU2734613C2 - Horizontal converter and combined melting-converting method - Google Patents

Abstract

FIELD: non-ferrous metallurgy.

SUBSTANCE: invention relates to processing of sulphide polymetallic concentrates and conversion of matte in combined melting-converting unit. Horizontal converter is equipped with an additional row of lower side tuyeres installed below said row of side tuyeres at distance of 0.4–0.8 m, wherein tuyere inclination angle to converter horizontal cross-section horizontal axis is from 2 degrees to 8 degrees. Melting-converting is performed with supply of oxygen-air blow to melt through side tuyeres and through additional row of lower side tuyeres, complex blowing of melt—with supply of oxygen-air blow to said tuyeres at ratio of gas flow rate supplied to upper row of side tuyeres to gas flow supplied to lower row of side tuyeres, equal to (1–2):(4–6), respectively.

EFFECT: invention increases melting-conversion efficiency by 1_1–1_3 times while increasing tuyeres and melting unit to 213–217 days.

2 cl, 2 dwg

Description

The invention relates to the field of nonferrous metallurgy, in particular to the processing of polymetallic sulfide copper-lead-zinc concentrate in horizontal converters of copper-smelting production.

Known methods of processing sulfide concentrates in standard and converted horizontal converters of copper smelting with side blast (Gudima N. In., Shein Ya.P. A short guide to non-ferrous metallurgy. M .: Metallurgy 1975, 535 p .; Naboychenko S.S. , Ageev N.G., Doroshkevich A.P., Zhukov V.P. Processes and devices of non-ferrous metallurgy.Yekaterinburg, URO RAS, 2005, 699 pp .; Skopov G.V., Starkov K.E., Haritidi G. P. et al. Method of processing sulfide copper-lead-zinc materials.RU 2520292, BI, 2014, 17; Zhukov V.P., Skopov G.V., Kholod S.I. Pyrometallurgy of copper. Yekaterinburg, URO RAS. 2016.640 p.). The disadvantages of these methods of processing and structural design of the unit is intense wear of refractory materials in the lateral zone of the tuyere belt, which limits the gas load on the tuyeres and the use of oxygen, reduces the rate of circulation of the melt in the volume of the bath, and reduces the productivity of the process.

There are also known analogs of the invention with the organization of only the bottom (bottom) blowing of the melt (Wei Kejian, Jiang Yumi, Zhang Zhengming, etc. Method and furnace for converting copper mattes by bottom blowing. RU 2647418. BI, 2017, 3; Zhukov V.P. , Skopov G.V., Kholod S.I. Pyrometallurgy of copper.Yekaterinburg, URO RAS. 2016. p. 361-364). To increase the bubbling zone and intensify the process structurally, the bottom tuyeres are staggered, which makes it possible to expand the boundaries of the reaction zone of the vertical flame. Bottom blowing of the melt reduces the heat density in the area of the side lining of refractories, which increases the campaign of the horizontal converter, but is not able to provide an intensive development of circulation flows and significantly increase the productivity of melting and converting.

The prototype of the invention (Zhukov V.P., Skopov G.V., Kholod S.I. Pyrometallurgy of copper. Yekaterinburg, URO RAS. 2016. P. 361-364) is a modified converter of copper smelting, hereinafter referred to as PAP (Smelting Unit "Victory"). Combined smelting of polymetallic sulfide raw materials and conversion into PAP, implemented (Skopov G.V., Starkov K.E., Haritidi G.P. and others. Method of processing sulfide copper-lead-zinc materials. RU 2520292, BI No. 17, 2014 ) at the Mednogorsk copper-sulfur plant (LLC "MMSK"). The technical characteristics of the PAP are shown below.

PAP specifications

The PAP melting unit (Fig. 1) is a cylindrical reactor (1), structurally designed in the form of an elongated converter with a gas neck (3) offset to one of the ends. The blast is fed through a row of lateral tuyeres (9) horizontally located to the mirror of the bath, installed below the level of the melt at a distance of 750 mm from the longitudinal horizontal axis of the converter. To increase the durability of the tuyeres and the service life of the lining in the area of their installation, a pipe-in-pipe design is used. Shielding gas (compressor air) is supplied to the outer annular cavity (shell) with a flow rate of 150-300 m ³ / h, and through the central pipe (main channel) an oxidizer: air with a flow rate of 800-1000 m ³ / h, or oxygen 800-1000 m ³ / h. The converter is lined with chrome-magnesite bricks. In order to reduce the rate of wear of the refractory lining of the PAP tuyere belt, cooled elements are installed in it above and below the axis of the tuyeres, which are cooled from a water cooling system under pressure (RWC). The presence of the VOPR system allows the use of oxygen-air blast (KVS) containing 22.9% vol. О ₂ and achieve a maximum productivity of 405.6 tons of concentrate per day with an increase in the unit campaign to 205 days.

The charge materials are loaded continuously through the feed throat (2), the matte is drained periodically, and the slag is continuously fed into the molds of the slag casting machine (12). Bulk, lumpy and briquetted materials are loaded through the feed throat in the reaction zone of the unit. The loading of bulky materials is carried out through the gas throat. The matte is poured through a throat that serves to remove gases. To pour the matte, the PAP is rotated 52 ° in the direction opposite to the tuyere line.

The discharge of the enriched matte is carried out through an outlet in the end wall of the furnace (8) and then through a lined chute (7) is poured into a ladle (6). Slag from the surface of the melt is removed continuously from the end part of the furnace through the tap hole (10) opposite to the charge, and then through the lined chute (11) it is poured directly into ladles or into molds. To evacuate gaseous products, a gas neck is provided, installed away from the reaction zone. The evaporative cooling dust cover consists of two parts: stationary (4) and rotary (5). The stationary part is made in the form of a rectangular flange connected to the gas pipeline. The swivel part of the dust cover, when raised to the upper position, completely opens up access to the neck for performing technological operations.

The main disadvantages of the prototype are:

1. A poorly developed circulation zone in the volume of the bath, due to the installation of only the side row of tuyeres, limits the productivity of melting, converting;

2. The use of only side tuyeres, even in the presence of a VOPR system, limits the further increase in the service life of the tuyere belt zone;

The objective of the present invention is to improve the design of the PAP and the method of introducing blast into the melt with the optimization of its costs, providing:

- increase in productivity;

- increasing the service life of tuyeres and structural elements in the area of their installation.

This problem is solved by the fact that in addition to the side row, one more lower row of tuyeres is installed in the PAP (13). When melting charge materials or converting, the furnace is rotated so that the vertical axis of the lower tuyeres coincides with the central vertical axis of the PAP (Fig. 2). In this case, the maximum volume of the reaction zone of the melt exposed to the bottom blast is achieved. The location of the melt processing by side blast jets is tied to this position of the unit, which is determined by the distance between the lower and side tuyeres in the range of values from 0.4 m to 0.8 m. Q _b to the lower Q _n , equal to Q _b / Q _n = (1-2) / (4-6), changes the nature of the movement of circulation flows in the wall region and the volume of the bath, in contrast to analogues and the prototype of the invention. This leads to an increase in the productivity of melting the solid charge and a higher digestibility of the bath lump flux. Installation of lateral tuyeres at an angle β = 2 ° -8 ° to the melt mirror, or to the central horizontal axis of the PAP cross-section, leads to swirling of the melt flow in its volume, with a moderate effect on the masonry of the lateral zone of the tuyere belt.

In the proposed invention, instead of compressor air, water vapor is considered as a protective gas, which ensures the flow of an endothermic reaction

The calculated endothermic effect Q in the oxidation of FeS alone is 18 kJ (t = 1300 ° C). At maximum flow of shell side cavity lances 29000⋅3 / 5 = 17400 m ³ / h of air blast, the amount of heat absorbed in the common wall region tuyere operation amount 17400⋅18 / 22,4 ~ 14000 kJ or 14000⋅10 ^3/3600 ~ 3900 W (3.9 kW). The heat load on the masonry in the tuyere belt zone, according to the prototype conditions, varies in the range of 63-85 kW / m ² , which implies a decrease in the heat intensity in this area by 4.6-6.0%. With a lining campaign of 205 days, one can approximately extrapolate an increase in its service life under these conditions to 213-217 days.

It is possible to use a mixture of water vapor and compressor air as a shielding gas.

The ratio in the tuyere water vapor (shell) -compressor air (main channel) less than 1/8 does not provide adequate cooling of the tuyere and the masonry area in the tuyere installation area. A ratio greater than 3/5 reduces the melting performance and the desulfurization rate.

The change interval of the basic values of the claims of the present invention was determined by the method of cold modeling. Water and vacuum oil were used as model fluids.

A typical fluid flow pattern is shown in FIG. 2. Circulation provides continuous renewal of the melt-gas interface in the purge zones, dissolution of solid batch materials, supply of the reagent, primarily sulfides, to the purge zone and removal of reaction products. In addition, the motion of the melt under the action of the jet reduces the degree of its overheating in the reaction zone and evens out the concentration and temperature profile in the bath.

From FIG. 2 it can be seen that in the volume of the melt, designated as the region "B", the direction of motion of the liquid masses during lateral and bottom blowing coincide. In this section, the maximum velocities of movement of the liquid phase are also noted, amounting to 0.3-0.5 m / s. In the area of the lateral tuyere, the circulation is 0.04-0.07 m / s. With a maximum gas load in excess of the ratio of the lateral blow to the lower one of more than 2/4, the velocity in the near-wall region of the tuyere belt zone sharply increases to 0.4 m / s, therefore, the maximum erosive wear of the masonry and the tuyere is likely here. When the ratio is less than 1/6, with predominant blowing with the lower tuyeres, it shows that the lower flows of liquid and jets intersect the side ones, the latter break up into small bubbles and the circulation rate decreases. According to the conditions of the prototype, the circulation rate of the melt at the value of the Archimedes criterion (Ar = 58) in the zone of the side tuyeres is 0.2 m / s.

An increase in the angle of inclination of the side tuyeres to the bath mirror more> 8 ° swirls the flow in the near-wall region of the side tuyeres to a greater extent, which increases the linear velocity of fluid movement to ~ 0.1 m / s and is impractical from the point of view of mechanical action on the lining in this area. Installing tuyeres with β <2 ° reduces the circulation rate in the reaction zone and reduces the completeness of the melt desulfurization, as well as the productivity of the process.

Since the rate of desulfurization is limited by the diffusion of sulfur in the volume of the melt (Zhukov V.P., Skopov G.V., Kholod S.I. Pyrometallurgy of copper. Yekaterinburg, URO RAS. 2016.640 p.), An approximate estimate of the oxidation rate was determined depending on the circulation melt and mass transfer of sulfur according to the equation

where υ is the specific rate of oxidation g-at S / cm ² / s, C _o is the sulfur concentration in the volume of the melt, we take constant, β is the mass transfer coefficient of sulfur in the volume, calculated from the criterion equation

где D - коэффициент диффузии серы в оксидно-сульфидном расплаве, 10^-10 м²/с (1400°С); Re - критерий Рейнольдса, равный wR/v; w - скорость циркуляции, м/с; R - радиус выхлопного сопла фурмы 0,024 м; v - коэффициент кинематической вязкости оксидно-сульфидного расплава, равный 1,5⋅10^-6 м²/с (1300°С); Pr - критерий Прандтля, определяемый как v/D.as

where D is the diffusion coefficient of sulfur in the oxide-sulfide melt, 10 ^-10 m ² / s (1400 ° C); Re - Reynolds criterion equal to wR / v; w — circulation speed, m / s; R is the radius of the lance exhaust nozzle 0.024 m; v - coefficient of kinematic viscosity of oxide-sulfide melt, equal to 1.5⋅10 ^-6 m ² / s (1300 ° C); Pr is the Prandtl test, defined as v / D.

After substituting the boundary values of β values into equation (3), calculated depending on the speed of fluid circulation according to the conditions of the prototype (0.2 m / s) and in the proposed invention (0.3-0.5 m / s), we obtain that when using a combined blast, along with an increase in the campaign of PAP and tuyeres, it is possible to approximately increase the rate of desulfurization and melting by a factor of 1.1-1.3.

Claims (2)

1. Horizontal converter for combined smelting-converting, containing a feed throat for loading charge materials, a gas throat with a dust cover, a number of side tuyeres for supplying oxygen-air blast, made in the form of a "pipe in a pipe" with a protective gas shell and located in the tuyere zone below the horizontal axis of the converter, tap holes for the discharge of enriched matte and slag, located in the end walls, characterized in that it is equipped with an additional row of lower side tuyeres, installed below the mentioned row of side tuyeres at a distance of 0.4 - 0.8 m, while the angle the inclination of the tuyeres to the central horizontal axis of the converter cross-section is from 2 degrees to 8 degrees, made in the form of a "pipe in a pipe" with water vapor supplied to the outer annular cavity as a protective gas shell, and oxygen-containing gas as an oxidizer into the inner tube. 2. The method of combined smelting-converting in a horizontal converter according to claim 1, including pouring matte, loading charge materials in the form of polymetallic sulphide concentrate and lumpy flux and melting-converting them with feeding oxygen-air blast into the melt through side tuyeres and through an additional row the lower side tuyeres with the ratio of the volume of water vapor to the volume of oxygen-containing gas (1-3) :( 5-8), while the converter is rotated about the horizontal axis, the lower row of tuyeres is immersed in the melt along the central vertical axis, ensuring a change in the movement of the circulation flows of the melt in the near-wall region and in the volume of the reaction zone of the melt and carry out complex blowing of the melt with the supply of oxygen-air blast to the said tuyeres at the ratio of the gas flow rate supplied to the upper row of side tuyeres to the gas flow rate supplied to the lower row of side tuyeres equal to (1- 2) :( 4-6), respectively.

Images