Lancing, lead

Dried lead concentrate, flux, and return dust are added to the converter through a lance during the smelting cycle. Oxygen enriched air is injected at the same time to carry out the smelting reactions and maintain the temperature. Once smelting is completed, the air is shut off and the reduction carried... 

The high lead slag from the smelting furnace is tapped continuously and transferred down a heated launder directly into the reduction furnace through a port in the side of the vessel. Lump coal for reduction is fed continuously to the furnace by conveyor and dropped direcdy into the bath. Heating for the endothermic reduction reactions is provided by oil injected down the lance. The combustion air stoichiometry is set at 95% of that required for complete oil combustion. Air is injected into the top of the furnace to afterbum the volatile materials from the coal and provide additional heat to the top of the furnace. Reduction temperatures range from 1170 to 1200°C to maintain slag duidity. 

The second term indicates that by increasing the melt temperature, e.g., by oxygen lancing, to 1850 °C, AG° for the reaction becomes more positive and the reverse reaction leading to retention of chromium in steel becomes favorable. Addition of a deoxidant, e.g., silicon as ferrosilicon, which forms an oxide stabler than Cr203, also leads to further recovery of chromium in steel ... 

Brittania A process for removing silver from lead, operated by Brittania Refined Metals in England, using ore from the Mount Isa mine in Australia. After initial concentration by the Parkes process, and removal of the zinc by vacuum distillation, the mixture, which contains silver (70 percent), lead, and some copper is treated in a bottom blown oxygen cupel in which lead and copper are removed by the injection of oxygen through a shielded lance. 

Isasmelt A two-stage lead smelting process. In the first stage, the lead concentrate is oxidized by injecting air down a Sirosmelt lance, using helical vanes to swirl the gas. In the second, the high-lead slag is reduced with coal. The process was developed by Mount Isa Mines and the CSIRO, Australia, and due for startup at Mount Isa in 1991. 

The Celox cell consists of a closed end solid electrolyte tube made of zirconia stabilised with magnesium oxide (MgO). Cr + Cf203 is used as the reference electrode. Pt/Pt-Rh( 10%) thermocouple is used for in situ temperature measurement and the Pi lead also serves as the lead for the cell for EMF sensing. The lance is dipped into liquid steel for measuring oxygen potential. Liquid steel acts as the second electrode of the cell. As mentioned earlier, these are disposable type and can be used only once. 

Tessier introduced the use of cryolite (AlNaaF ) for the yellow coloring of stars, lances, and Bengal lights. In his second edition he includes a chapter on the small pyrotechnic pieces which are knonm as Japanese fireworks, giving formulas for them, and another on the picrates, which he studied extensively. The picrates of sodium, potassium, and ammonium crystallize in the anhydrous condition. Those of barium, strontium, calcium, magnesium, zinc, iron, and copper are hygroscopic and contain considerable water of crystallization which makes them unfit for use in pyrotechnic compositions. Lead picrate, with 1 H3O, detonates... 

Lespedeza (lespedeza) Leucaena (lead tree) Lonchocarpus (lance pod) Lotononis (lotononis)... 

Effects of Deposits on the Catalv.sts- In describing techniques for regenerating commercial VOC oxidation catalysts of noble metals on ceramic honeycombs, Heck et al. pointed out that generally below 450 C the presence (in the gas stream) of phosphorous and other metals, particularly as oxides, leads to catalyst deactivation by simple masking as opposed to poisoning by chemical interaction. These deposits can often be removed by chemical treatment with acid or alkaline solutions and sometimes by physically cleaning with a compressed air lance. When combustible... 

K.R. Robilliard P.J. King and W.E. Short, "The Application of Ausmelt s Top Submerged Lancing Technology to the Lead Industry", Eleventh International Lead Conference. Venice, Italy, 25-27 May, 1993. 

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