Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B13/00—Obtaining lead
  • C22B13/02—Obtaining lead by dry processes
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B13/00—Obtaining lead
  • C22B13/06—Refining

Definitions

• the invention relates to a process for the continuous direct melting of metallic lead from sulfur-containing lead materials in an elongated, lying reactor, wherein a melt of a slag phase and a lead phase is maintained in the reactor, the slag phase and the lead phase are passed through the reactor in countercurrent, the gas atmosphere is passed through the reactor in countercurrent to the slag phase, in the oxidation zone lying to the side of the lead tap, oxygen is blown into the melt in regulated amounts from below, and sulfur-containing lead material is charged to the melt in controlled amounts, in which the slag tap lies to the side Reduction zone reducing agents are introduced into the melt and the gas space is heated, the oxidation potential in the oxidation zone is set such that an autothermal melting of the feed into slag containing metallic lead and lead oxide e followed and the amount of reducing agent and the temperature in the reduction zone are regulated so that a low-lead slag is formed.
• DE-OS 28 07 964 discloses such a process for the continuous conversion of lead sulfide concentrates into a liquid lead phase and a slag phase in an elongated, lying reactor under a gas atmosphere containing zones of SO 2 , with sulfidic lead concentrates and additives being charged onto the melt , the lead phase and a low-lead slag phase are discharged at the opposite end of the reactor and the phases flow in countercurrent to one another in substantially continuously layered streams to the outlet ends, at least a portion of the oxygen through a plurality of independently controlled and along the length of the oxidation zone of the reactor distributed nozzles is blown into the melt from below, the solid feed is gradually charged into the reactor by a plurality of independently controlled feeders which are distributed over a considerable length of the reactor, the gradie nt the oxygen activity in the melt is adjusted by choosing the local addition and control of the amounts of oxygen and solid material introduced so that it progressively progresses in the reduction zone to a minimum for the production of lead at
• reducing substances are introduced into the melt to produce a low-lead slag, and the gas space is heated.
• the reduction heat is applied by the heating and the temperature increase of the slag is achieved in the reduction zone.
• Calming zones into which no gases are blown into the melt, can be arranged between the oxidation and reduction zones and in front of the oxidation zone and behind the reduction zone.
• the temperature of the melt should be kept as low as possible both in the oxidation zone and in the reduction zone. As a result, the attack of overheated slag on the masonry and the cooling of the masonry that is otherwise required at higher temperatures, a strong evaporation of metals or metal compounds and an unnecessary heating of the lead phase are avoided. At low working temperatures, however, there is a risk of the melt subcooling due to operating fluctuations.
• a direct lead melting process in which a mixture of fine-grained lead sulfide and oxygen strikes a melt bath from above with ignition and flame formation, with a considerable part of the oxidation already taking place in the furnace atmosphere.
• the flame temperature is over 1 300 ° C and the temperature of the melt between 1 100 and 1300 ° C.
• the slag phase and furnace atmosphere flow through the furnace in cocurrent.
• the slag is withdrawn from the furnace with at least 35% lead as lead oxide and reduced in a separate reduction furnace.
• To generate the lead phase 98 to 120% of the stoichiometrically calculated amount of oxygen is required, which would be necessary for a complete conversion of the lead sulfide into metallic lead.
• An oxygen addition of approximately 120% can be used for short periods to increase the transition of lead oxide into the slag and thus to control the furnace temperature.
• this temperature control is not suitable for the process described above with an oxidation and reduction zone in a reactor with the deduction of a low-lead slag.
• this temperature control does not prevent the disadvantages of high melting temperatures with overheated slag.
• the invention has for its object a direct lead melting process of the ge to operate as described in such a way that the temperatures of the melt in the entire reactor are kept as low and constant as possible and undercooling of the melt is prevented even when the operating mode fluctuates.
• the temperature of the melt in the reduction zone is kept constant by regulating the auxiliary heating, and the temperature of the melt in the oxidation zone is regulated by regulating the ratio of oxidizable sulfur to oxygen in such a way that at an increase in temperature increases the ratio of sulfur to oxygen to reduce the lead oxide content of the slag, decreases the ratio of sulfur to oxygen to increase the lead oxide content of the slag when the temperature is lowered, and the increase or decrease in the ratio of sulfur to oxygen takes into account the heat content of the gases entering the oxidation zone from the reduction zone is controlled as a result of the changed lead oxide content of the slag.
• oxidizable sulfur only the sulfur bound to lead as the sulfide is specified as oxidizable sulfur and only the oxygen supplied in gaseous form as oxygen. If the temperature in the oxidation zone rises above the desired value, the ratio of oxidizable sulfur to oxygen introduced in the oxidation zone is increased, as a result of which more metallic lead is produced and less PbO is introduced into the slag and, accordingly, less heat is generated.
• the ratio of sulfur to oxygen is not increased in accordance with the rise in temperature, since the reduced PbO content of the slag as it enters the reduction zone results in a reduction in the reduction work required there. Since the temperature in the reduction zone is kept constant, less heat is introduced there by the auxiliary heating and accordingly the gas from the reduction zone introduces less heat into the oxidation zone with a certain time delay. This reduced amount of heat is taken into account when increasing the ratio of sulfur to oxygen and the ratio of sulfur to oxygen is only increased accordingly. If the temperature in the oxidation zone drops, the procedure is reversed. Without keeping the temperature in the reduction zone constant and without taking into account the changed heat content of the gases entering the oxidation zone from the reduction zone, a change in the ratio of sulfur to oxygen leads to permanent temperature fluctuations.
• the ratio of sulfur to oxygen When the ratio of sulfur to oxygen is increased, the evaporation of PbS is increased, which also results in a certain cooling effect, while when the ratio is reduced the reverse effects occur.
• the amount of change in the ratio of sulfur to oxygen with a change in temperature in the oxidation zone depends on the reactor and the operating conditions. The required size can be calculated or determined empirically. The regulation can also take place gradually.
• a preferred embodiment consists in that the temperature of the melt in the oxidation zone is set at 900 to 1000 ° C and in the reduction zone at 1100 to 1200 ° C. At these temperatures, a good reaction rate is achieved in the oxidation zone and a low-lead slag in the reduction zone with low oxygen consumption and heat consumption, and undercooling of the melt can be avoided with certainty by means of the temperature control. In addition, the evaporation losses are still relatively low.
• a preferred embodiment is that in the oxidation zone a slag type of 45 to 50% ZnO + FeO + Al 2 O 3 , 15 to 20% Ca0 + MgO + BaO and 30 to 35% Si0 2 , calculated on lead-free slag, with 30 up to 70% PbO is set.
• This type of slag enables the maintenance of low temperatures with good operating results.
• a galena concentrate which contained 73.6% Pb and 15.8% S, was mixed with 20% lead sulfate fly dust (62.3% Pb, 6.5% S) and slag-forming additives and pelletized, resulting in pellets with the following composition:
• PbS-rich pellets were continuously placed in a refractory brick reactor with the shape of a horizontal cylinder 4.50 m in length and 1.20 m in diameter knife charged, which was equipped on the front face with an auxiliary burner and an overflow stitch for the slag and on the rear face with an exhaust gas opening.
• the charging opening was arranged on the jacket of the reactor in the immediate vicinity of the end wall on the flue gas side.
• the reactor was charged with 2.5 t of metallic lead and 1 t of lead oxide-rich slag (65% Pb), which were melted down with the help of the burner and heated to a temperature of 950 ° C.
• Technically pure oxygen was then blown into the lead bath at the bottom of the reactor in such a time quantity that the pellets charged to the bath were converted to metallic lead, slag rich in lead oxide and SO 2 gas laden with dust.
• the Pb content of the slag was 63.7% under these conditions.
• the temporal pellet quantity was then carefully increased. It was found that a melt temperature of 950 ° C. was reached with a pellet quantity of 2.7 t / h.
• the slag flowing out of the reactor contained only 48.4% Pb, while the lead contained in the pellets was distributed 51% to the metal phase, 29% to the slag phase and 20% to the gas phase.
• the advantages of the invention are that low temperatures are used, cooling of the reactor is avoided, heat consumption and oxygen consumption are kept to a minimum, and nevertheless undercooling of the melt can be avoided with certainty.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Manufacture And Refinement Of Metals (AREA)

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Publications (2)

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• 1980
  • 1980-08-06 DE DE19803029741 patent/DE3029741A1/de not_active Withdrawn
• 1981
  • 1981-05-13 DE DE8181200510T patent/DE3161937D1/de not_active Expired
  • 1981-05-13 EP EP81200510A patent/EP0045532B1/de not_active Expired
  • 1981-05-13 AT AT81200510T patent/ATE5902T1/de not_active IP Right Cessation
  • 1981-05-14 ZA ZA00813228A patent/ZA813228B/xx unknown
  • 1981-05-22 IN IN542/CAL/81A patent/IN154359B/en unknown
  • 1981-05-27 ES ES502523A patent/ES8203978A1/es not_active Expired
  • 1981-05-27 AR AR285463A patent/AR225515A1/es active
  • 1981-06-08 US US06/271,078 patent/US4397688A/en not_active Expired - Lifetime
  • 1981-07-17 YU YU1769/81A patent/YU43026B/xx unknown
  • 1981-07-20 FI FI812263A patent/FI70729C/fi not_active IP Right Cessation
  • 1981-07-30 BR BR8104918A patent/BR8104918A/pt unknown
  • 1981-07-31 ZM ZM70/81A patent/ZM7081A1/xx unknown
  • 1981-08-03 PH PH25996A patent/PH19065A/en unknown
  • 1981-08-04 KR KR1019810002825A patent/KR850001254B1/ko not_active Expired
  • 1981-08-05 MA MA19435A patent/MA19235A1/fr unknown
  • 1981-08-05 PL PL23249681A patent/PL232496A2/xx unknown
  • 1981-08-05 AU AU73700/81A patent/AU545143B2/en not_active Ceased
  • 1981-08-05 CA CA000383280A patent/CA1171289A/en not_active Expired
  • 1981-08-06 JP JP56123561A patent/JPS5757847A/ja active Granted

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