Lead recovery

For environmental reasons, the entire process is handled by enclosed equipment. Lead recoveries of 96% can be obtained from the raw materials, and sulfur dioxide gas released in the process is used to produce sulfuric acid. Four plants are in operation as of 1994. Three are in Russia and one is in Italy. 

The process is flexible and permits treatment of a wide variety of plant feed materials. Overall lead recovery is in the range of 96—98%. The operation is, however, cycHc which increases the cost of the sulfur fixation plant, and any 2inc contained in the concentrate is lost in the slag unless slag Aiming is added or already available at the site. 

Secondary Lead. The emphasis in technological development for the lead industry in the 1990s is on secondary or recycled lead. Recovery from scrap is an important source for the lead demands of the United States and the test of the world. In the United States, over 70% of the lead requirements are satisfied by recycled lead products. The ratio of secondary to primary lead increases with increasing lead consumption for batteries. WeU-organized collecting channels are requited for a stable future for lead (see BATTERIES, SECONDARY CELLS Recycling NONFERROUS METALS). 

When using Na2S as the sulphidizer, aeration with sulphidizer was proven to be beneficial. When cerussite is only slightly sulphidized, it is sensitive and, with the absence of aeration, rapidly loses floatability. Studies conducted on lead oxide flotation from mixed ore showed that without aeration, low lead recoveries were achieved. Table 20.3 shows the effect of aeration with sulphidizer on lead oxide metallurgical results. 

Let us suppose that we are interested in implementing this procedure in our laboratory and we fix the time of agitation at 10 min. So, we want to look for the RC (Xi) and pH (X2) values that provide the largest percentage lead recovery (Y), and we will use the simplex method defined by Spendley etal [16]. 

Step 4 carry out the experiment in the new conditions (reflected vertex). It sometimes happens that the proposed coordinates for the reflected point are outside boundaries, and in that case it is not possible to make the experiment and point R gets a response which is worse than that of the worst vertex. In our example, the new coordinates for R allow us to perform the experiment, so we obtain experimentally the response in the reflected R in the example this is a 71% lead recovery (Y = 71). Now we have vertex number 4 (Table 2.26). 

Repeating the previous five steps successively, the simplex moves towards an optimal point. In this case it will be the point that provides the highest percentage lead recovery (Y). Table 2.28 summarises the evolution of the simplex until the optimum is reached. 

We see that between R and W, the lead recovery (response) has improved to 71-50% =21%, so R should be the new B of simplex number 2. This suggests us that, perhaps, in the (W - R) direction we might obtain better responses. To assess this, a new point E (expanded) can be defined, whose coordinates are calculated as... 

F. Rashchi, A. Dashti, M. Arabpour-Yazdi, and H. Abdizadeh, Anglesite flotation a study for lead recovery from zinc leach residue. Minerals Engineering 18(2) (2005). 

Castillo, M., Pina-Luis, G., Diaz-Garcia, M.E., Rivero, I.A. Solid-phase organic synthesis of sensing sorbent materials for copper and lead recovery J. Braz. Chem. Soc., 2005, 16, 412-417... 

Although substantial work has been carried out on the recovery of lead from battery residues by electrolytic means, no system has been adopted for large-scale commercial operations. Companies such as Engitech Impianti in Italy and RSR in the USA have patents on electrolytic systems, whilst a European consortium, led by Tecnicas Reunidas in Spain, has developed the chloride-based PLACID and FLINT lead recovery processes. 

This method was unsatisfactory in terms of workers health (prolonged exposure to lead) and lead recovery (as plates treated were not clean since they contained 8-10% plastic materials, and due to the simultaneous reduction of Pb/Sb grids along with the active mass). 

The technological advances in the lead/acid accumulators field have made lead recovery easier and safer for the enviroiunent. At the same time, the lead metallurgy has become environmentally friendly as well. 

Nevertheless, the assumptions were conservative in the sense that the predictions based on them likely represent an upper limit for the impact on the lead-acid battery recycling industry. The mass of lead in scrap EV batteries is projected to increase as shown in Figure 9, reaching about 16,000 metric tons in 2005. This can be compared to Figure 10, which shows the amount of lead from battery scrap and the total amount of lead recovered from scrap in the U.S. through the year 1995 from U.S. Bureau of Mines data. Total secondary lead is nearing IM metric tons per year. The predicted EV battery lead mass in 2005 is only about 1.5% of the secondary lead recovery capacity in 1996 and will actually be less than that in 2005 once the future growth in secondary lead recovery is included. Clearly EV battery waste will remain a very small portion of secondary lead production well beyond 2005. 

Fig. 10. Lead from Battery Scrap, Total Lead Scrap, Secondary Lead Recovery Capacity, and Lead Scrap Export in the U.S.

USEPA. (2003). Innovative Technology Evaluation Report Electrochemical Design Associates (Formerly Geokinetics International, Inc.) Lead Recovery Technology Evaluation at the Building 394 Battery Shop. Pearl Harbor Naval Shipyard and Intermediate Maintenance Facility, Honolulu, HI. EPA/540/R-04/506. 

United States Environmental Protection Agency (EPA) SITE Program. (2003). Electrochemical Design Associates, lead recovery evaluation, building 394 battery shop Pearl Harbor Naval Shipyard and Immediate Maintenance Facility. Innovative Technology Evaluation Report. http //www.epa.gov/ORD/SITE/, EPA540/R-04/506 (accessed April... 

ERDC treatability study predictions of electrokinetic extraction performance EDAs lead recovery technology evaluation... 

Lead Recovery Technology, Electrochemical Design Associates (EDA)... 

Because the casing makes up about 7% of the total battery and the used batteries are recycled primarily for lead recovery, PP is obtained without additional cost and in substantial quantities to warrant the operation of a plastics recycling plant. 

Production of lead bullion low in sulfur as well as a disposable low-lead slag in one continuous operating converter at a lead recovery rate highm than 98%. 

Table I - Lead Recovery during Smelting as a Function of Feed Grade...

The new PLACID plant would be annexed to an existing battery recycling plant. Overall lead recovery of the combined PLACID-Pyro plant was estimated to be above 99.5%. 

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