Hard lead

Cathodes are made from graphite, soft or hard lead, or copper. A production-size cell (81) may contain 44 anode units, each comprising five graphite plate electrodes 25-mm thick, 175-mm wide, and 1100-mm long. 

Similar to other types of water treatment, AC filtration is effective for some contaminants and not effective for others. AC filtration does not remove microbes, sodium, nitrates, fluoride, and hardness. Lead and other heavy metals are removed only by a very specific type of AC filter. Unless the manufacturer states that its product will remove heavy metals, one should assume that the AC filter is not effective in removing them. 

Komposition,/. composition Dyeing) tin composition (solution of tin in aqua regia) hard lead. 

Example I. Hard lead (antimoniacal) can be used in sulphuric acid to quite high concentration but it displays an increasing corrosion rate with increasing temperature and concentration. Relationships are complex, but the general form of the equation may be used ... 

SS/MA may be structured in different ratios of sulfonated styrene to maleic anhydride. Typically, it is 3 1 (20,000 MW) or 1 1 (15,000 MW). The application rates of all calcium phosphate scale/sludge inhibitors or stabilizers vary, based on the amount of calcium present in the cooling system, with increased calcium hardness leading to higher levels of polymer required. 

Antimony is used in many alloys, chiefly for its props of hardening the softer metals, such as Pb. The best known of these alloys are type metal, bearing metal, hard lead and pewter. The powdered Sb is used in some pyrotechnic compns, as a fuel (Ref 9, p 32) and as a source of white light (Refs 3a 8)... 

Occasionally a species of whito lead is produced by tho Dutch method, which yields on analysis numbers corresponding to the formula 3 (Pb 0, COa) Pb 0, IIO that is, three equivalents of carbonate to one of oxide of lead. It has a loose friable texture when drawn from the heights, quite distinct from the hard cratos of whito lead obtained when the metal is almost wholly converted and is invariably the result of defective corrosion of tho motal. This kind of white lead does not cover so well as the hard lead. 

Hard lead 96-92 4-8 Cast shapes, wrought sheet and pipe. 

Plumbic powder No. 1 is made from lead nitrate 12 parts, potassium nitrate 2 parts, and black alder charcoal 3 parts.42 The materials are powdered and mixed, and then rolled in a wooden ball-mill with balls of hard lead (Pb 5, Sb 1) or brass or bronze. 

Chlorinated (shrinkprool) wool showes a different coloristic behavior. Dye uptake and release is facilitated wetfastness is reduced. In contrast, an antifelt treatment with a synthetic resin hardly leads to any change in coloristic behavior. 

Theoretically, hardness in the effluent from a sodium softener can be less than 1.0 ppm as CaC03. In practice, effluent quality from a sodium softener is dependent on the influent water quality. Higher influent hardness leads to higher effluent hardness. The total dissolved solids (TDS) concentration in the effluent from the softeners should be equivalent to that of the influent water since no TDS is removed through the softener instead sodium replaces hardness in the treated stream. The effluent will have a much higher concentration of sodium and lower concentration of hardness than the influent has. 

The raw material should contain at least 50 per cent, of Ca3P208 and be as free as possible from sesquioxides. It may be ignited if high in organic matter, reduced to a fine powder, and fed continuously into tanks lined with wood or hard lead alloy, where it meets on the counter current principle hot sulphuric acid of about 5 per cent, concentration. The reaction is quickly completed and the precipitated calcium sulphate is allowed to settle and filtered off continuously through filter presses. This sulphate is phosphatic gypsum and contains 3 to 4 per cent, of phosphoric acid of which 1 per cent, is soluble in water. The solution is evaporated in wrought-iron pans up to a concentration of 50 per cent, phosphoric acid, which may be further refined for use in pharmaceutical products or foods. 

Figures 8 and 9 show a m tration kettle with inner cooling, such as is used for nitrating aromatic hydrocarbons, and a separating funnel equipped with a hard lead or ceramic stopcock and having a window (lunette). The apparatus used for nitrating benzene must be completely lead lined because the spent acid is highly diluted at the end of the nitration and attacks iron.

Stoneware stopcocks of small sizes are widely used and last indefinitely if properly handled. Hot liquids are injurious to them because of the danger of cracking, and proper lubrication must be used to prevent freezing. So-called reinforced stoneware stopcocks, which are more resistant to shock and also to heat, have a protective housing made of leaded sheet iron. They have entirely rqilaced the older hard lead (antimony-lead ) type. Stoneware is also used for supply lines, valves, and centrifuges. The basket of a stoneware centrifuge is placed in a steel bas-... 

MOLYBDENA — Hard Lead Incrustations found at the Bottom of the Furnace. 

Hard Lead, composed of Spume of Silver and Lead Ore. 

Tartaric Acid.— The usual concentration of the filtered solution is from 30 to 70 per cent of solids, and the work is done in single-effect evaporators made entirely of hard lead with extra-heavy lead coils. The all-lead construction may be replaced by a cast-iron shell with suitable lead lining, and the tubular heating surface with vertical tubes and lead flueplates can be used instead of the lead coils. It is very important that the construction is such that tubes can readily be cleaned from the hard scale produced by the calcium sulphate in the solution. With a steam pressure of from 30 to 50 lb. in the coils, and a vacuum of 27 in., the capacity is from to 2 gal. per square foot. 

Copper may also be recovered from leach solutions electrolytically. Electrowinning requires the use of an insoluble anode such as hard lead, comparable to the liberator cell used for liquor purification in copper electrorefining. Consequently, there are net electrochemical reactions involved in electrowinning (Eqs. 13.20 and 13.22), as opposed to the situation with electrorefining, so that about 1.7 V are required for this step. This results in a much higher electrical power consumption of about 2.8 kWh/kg copper for electrowinning, compared to about 0.2 kWh/kg for electrorefining. 

However, except for very low values of the spins, and also certain special cases, these calculations become very long and tedious and, as we shall see in Sect. 3C, can hardly lead to any very general formulae. 

Although an increase upon irradiation was observed for cumene cracking over silica-alumina by Panchenkov et al. (95), it is hard to reconcile the results in detail. The rate constant at 400° was raised from 0.0014 to 0.0024 by about 7 x 10 ev/gm from 1-mev protons, which is reasonably in accord with the neutron results, but it was raised to 0.0062 by about 3 x 10 i ev/gm from Co y-rays. In order to persist at 400°, the enhancement must almost surely result from displaced atoms, and a smaller dose of y-rays (with less intrinsic ability to displace atoms) could hardly lead to a larger effect, unless the activity vs displaced atom curve has a maximum at a rather low value. 

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