Spent lime

The calcium oxide product is supplemented with fresh limestone and returned to the fluidized bed. Two undesirable side reactions can occur in the regeneration of spent lime leading to the production of calcium sulfide ... 

The success of this process depends on the low solubility of calcium carbonate, which is also what allows this process to be used for small-scale production of sodium hydroxide by a batch process. For batch operation, the functions such as slaking, mixing, and settling may be carried out in the same wooden (or steel) vessel. Separate units are required for these steps in the continuous process. A further chemical feature important to the recycle of the spent lime of this process is the relatively easier thermal loss of carbon dioxide from calcium carbonate than from sodium carbonate. Since sodium bicarbonate (NaFICOs) may be calcined at 175°C to obtain carbon dioxide loss, it might be expected that sodium hydroxide could be made by heating sodium carbonate at a higher temperature followed by hydration of the resulting oxide (Eqs. 7.21 and 7.22). 

Two of the solid waste streams, spent pea gravel and spent lime, would be defined as hazard-... 

Test Parameter Total Metals Lresh Pea Gravel Lresh Lime Spent Pea Gravel (from Detonation Chamber Floor) Spent Lime (from Lime Injection Systems)... 

Considering that the TDC produces a relatively small amount of secondary waste, including scrap metal, pea gravel, and spent lime, off-site treatment and disposal of secondary wastes are not going to be a big concern. Much less secondary waste will be produced by the TDC than by the planned neutralization of the bulk of the chemical weapons at both BGCAPP and PCAPP. In addition, off-the-shelf treatment technologies are available in the United States for treatment of the secondary wastes produced by the TDC. 

The TC-60 TDC produces relatively small amounts of secondary waste. These are described in Chapter 3. It is likely that the spent lime and spent pea gravel will not be a RCRA hazardous waste for mercury since the Levinstein mustard agent in the projectiles at BGAD contains low levels of mercury. Overall, the secondary waste, including the spent activated carbon, is not expected to contain compounds of regulatory concern. The scrap metal is thermally decontaminated to a... 

Jabtohski s work was interrupted once again by World War II. From 1939 to 1945 Jabtonski served in the Polish Army, and he spent lime as a prisoner of first the Germany Army and then the Soviet Army. In 1946 he returned to Poland to chair a new Department of Physics in the new Nicholas Copernicus University in Toruh. This beginning occurred in the very difficult postwar years in a country totally destroyed by World War II. Despite all these difficulties, Jabtohski with... 

Pulverised fuel ash, sawdust, spent lime and many other waste products can and have been used in some apphcations usually where a rou separation is required. Other eciahy prepared solid powder materials such as hydrated magneaum silicate, hydrated calcium silicate, bentonite, fuller s earth, or activated carbon are used in some applications piinc ally because of their adsorptive properties but they may also act as a filter aid in the separation of the particulate solids fi om the liquid. 

There is interest in lime sludge classification in both wastewater and potable water treatment plants. If the magnesium hydroxide content of a lime sludge can be suitably reduced, the residual calcium carbonate can be recalcined to calcium oxide. Too much magnesium hydroxide will prevent the slaking of the lime. The restrictions and rising cost of disposal of spent lime makes recovery and recycling attractive. 

Pneumatic conveying system spent lime removal... 

Most carbide acetylene processes are wet processes from which hydrated lime, Ca(OH)2, is a by-product. The hydrated lime slurry is allowed to settle in a pond or tank after which the supernatant lime-water can be decanted and reused in the generator. Federal, state, and local legislation restrict the methods of storage and disposal of carbide lime hydrate and it has become increasingly important to find consumers for the by-product. The thickened hydrated lime is marketed for industrial wastewater treatment, neutrali2ation of spent pickling acids, as a soil conditioner in road constmction, and in the production of sand-lime bricks. 

The softened seawater is fed with dry or slaked lime (dolime) to a reactor. After precipitation in the reactor, a flocculating agent is added and the slurry is pumped to a thickener where the precipitate settles. The spent seawater overflows the thickener and is returned to the sea. A portion of the thickener underflow is recirculated to the reactor to seed crystal growth and improve settling and filtering characteristics of the precipitate. The remainder of the thickener underflow is pumped to a countercurrent washing system. In this system the slurry is washed with freshwater to remove the soluble salts. The washed slurry is vacuum-filtered to produce a filter cake that contains about 50% Mg(OH)2. Typical dimensions for equipment used in the seawater process may be found in the Hterature (75). 

Typical values for mf n are 0.5 to 2.5. Gommercially used bases include sodium hydroxide, potassium hydroxide, calcium hydroxide (lime), magnesium hydroxide, sodium carbonate, sodium alurninate, calcium carbonate, or various mixtures. For certain appHcations, PAG can be made from waste grades of aluminum chloride [7446-70-0] such as spent catalyst solutions from Friedel-Grafts synthesis (see Friedel-Grafts reaction). 

Sodium bicarbonate precipitates from solution and is recovered by filtration. Ammonium chloride is then crystallised from the filtrate, separated, washed, and dried. The exact proportion of ammonium chloride recovered depends on the relative demands for sodium carbonate and ammonium chloride. If economic conditions requite, part of the ammonia can be recovered and returned to the hrine-ammoniation step by distillation of the ammonium chloride solution ia the presence of lime. The spent calcium chloride Hquor, a final product ia manufacture of sodium carbonate by the ammonia—soda process, can also be used to obtain ammonium chloride. This Hquor is treated with ammonia and carbon dioxide... 

The mixture is stirred at room temperature for an additional 60 hours (Note 4), during which time the calcium chloride tulie may become spent and need replacement. The viscous, light-yellow liquid product is transferred to a large crystallizing dish and dried in a vacuum desiccator over soda-lime for about 24 hours (Note 5). 

End-kohlenstoff, m. terminal carbon (atom), -lage,/. end position final position, -lauge, /. final liquor spent liquor or solution (pf.) foots, -laugei lk, m. (Agric.) a product made by treating the mother liquor from potassium chloride manufacture with lime. 

Spent pickle liquor is considered a hazardous waste (K062) because it contains considerable residual acidity and high concentrations of dissolved iron salts. For example, spent pickle liquor and waste acid from the production of stainless steel is considered hazardous. The hazardous constituents in K062 are lead, nickel, and hexavalent chromium. Waste pickle liquor sludge generated by lime stabilization of spent pickle liquor is not considered hazardous unless it exhibits one or more of the characteristics of hazardous waste. An estimated 6 million tons of spent pickle liquor are generated annually in the U.S.1... 

Nickel sulfate can be produced from either pure or impure sources. The pure source involves the reaction of pure nickel or nickel oxide powder (combined or separately) with sulfuric acid to produce nickel sulfate that is filtered and crystallized to produce a solid product. The impure raw material may be spent industrial liquor that contains a high percentage of nickel sulfate. The impurities in the liquor are precipitated by sequential treatment with oxidizers lime and sulfides can later be filtered out. The treated liquor, which is a pure solution of nickel sulfate, can be packaged in a drum or further crystallized and dried to produce solid nickel sulfate. Nickel sulfate is used mainly in the metal plating industries. Other uses include dyeing and printing of fabrics and production of patina, an alloy of zinc and brass. 

Through the late 1980s, spent pickle liquor was traditionally land disposed by steel manufacturers after lime neutralization. The lime neutralization process raises the pH of the spent acid and makes heavy metals in the sludge less likely to leach into the environment. Today, however, some of the spent pickle liquor can be recycled or regenerated on-site by steel manufacturers.5... 

Interaction is exothermic, and if air is present, incandescence may occur with freshly prepared granular material. Admixture with oxygen causes a violent explosion [1], Soda-lime, used to absorb hydrogen sulfide, will subsequently react with atmospheric oxygen and especially carbon dioxide (from the solid coolant) with a sufficient exotherm in contact with moist paper wipes (in a laboratory waste bin) to cause ignition [2], Spent material should be saturated with water before separate disposal. Mixture analogous to soda-lime, such as barium hydroxide with potassium or sodium hydroxides, also behave similarly [1],... 

The types of reactions involving fluids and solids include combustion of solid fuel, coal gasification and liquefaction, calcination in a lime kiln, ore processing, iron production in a blast furnace, and regeneration of spent catalysts. Some examples are given in Sections 8.6.5 and 9.1.1. 

The spent solution is regenerated by mixing it with lime or limestone where the following reactions occur ... 

Absorbent availability could have significant impact upon process costs. Most spent alkali streams could be used depending on the other impurities present. Corrosion or precipitation tests should be considered for these cases. Any other readily available alkali, like sodium carbonate or sodium hychloride, should be considered. Slurry solutions of lime or limestone should be avoided because of past operating problems. 

---