Patent Number: 060751762
Section: description

EXAMPLE 1 The present process was tested with a simulated incinerator ash mixture, the composition of which is given in Tables 1 and 2 below. TABLE 1 ______________________________________ Component Concentration, g/kg ______________________________________ Volatile ash 387.96 Ash slag 320.07 Vermiculite 193.98 Activated carbon 48.49 Cr.sub.2 O.sub.3 14.80 NiO 6.16 PbO 5.22 CdO 5.54 CsCl 6.15 Ce.sub.2 O.sub.3 5.70 HgCl.sub.2 6.56 ______________________________________ TABLE 2 ______________________________________ Volatile ash, Ash slag, Oxide mass % mass % ______________________________________ SiO.sub.2 (amorphous) 16.5-45.6 40-45 SiO.sub.2 (crystalline) 3.4-9.4 -- Al.sub.2 O.sub.3 10-35 18-26 CaO 0.33-2 1-12 Fe.sub.2 O.sub.3 3-24 5-20 MgO 0.5-0.8 0.75-3 ______________________________________ A mixture of iron oxides (from chemical reagents) was used as the iron-containing part. The components had the following ratios (mass %): EQU FeO:Fe.sub.2 O.sub.3 :Fe.sub.3 O.sub.4 =25:40:35 The slurry had the following composition (mass %): Waste:Iron Oxides:70% concentration H.sub.3 PO.sub.4 solution=40:10:50. The composition was mixed for 20-30 minutes, and put into molds of 25 mm diameter and 40 mm height. The hardening of the mixture took 4 hours. The leaching data for radioactive and toxic elements for the cement samples that have cured for 28 days are given below in Table 3 (TCLP method) and Table 4 (ANSI 16.1 method). The values obtained do not exceed the respective maximum allowable values. EXAMPLE 2 The present process was tested with the simulated incinerator ash, the composition of which is given in tables 1 and 2. Metallurgical cinder waste was used as the iron-containing part. It was assayed and had the following ratio of iron oxides (mass %): EQU FeO:Fe.sub.2 O.sub.3 :Fe.sub.3 O.sub.4 =40:10:50 The components of the slurry had the following ratios (mass %): Waste:Iron Oxides:50% concentration H.sub.3 PO.sub.4 solution=30:15:55. PA1 Compression strength: .sigma..sub.comp =3570-3700 psi; PA1 Open porosity: P.sub.o =5.3 vol. %; PA1 Bulk density: .rho.=1.99 g/cm.sup.2. The composition was mixed for 20-30 minutes, and put into molds of 25 mm diameter and 40 mm height. The hardening of the mixture took 4 hours. After curing for 28 days, the characteristics of the cement samples have been identified: The leaching data for radioactive and toxic elements for the cement samples that have been curing for 28 days are given below in Table 3 (TCLP method). The values obtained do not exceed the respective maximum allowable values. TABLE 3 ______________________________________ (TCLP method) Concentration in the leachant, mg/l Cd Cr Ni Pb Hg Ce Cs ______________________________________ Example 1 0.12 0.042 5.5 0.001 0.052 0.005 0.18 Example 2 0.14 0.11 3.5 0.003 0.18 0.005 1.2 Allowable 0.19 0.86 5 0.37 0.2 -- -- values ______________________________________ TABLE 4 ______________________________________ (ANSI 16.1 method) Leaching index, Li Ce Cs Cd Cr Pb Hg Ni ______________________________________ Example 1 14.4 10.5 12.5 13.7 16.4 16.4 8.3 ______________________________________ EXAMPLE 3 The present process was tested with simulated incinerator ash, the composition of which is given in Tables 1 and 2. Naturally occurring magnetite, Fe.sub.3 O.sub.4, was used as the iron-containing part. Two samples were prepared. The components had the following ratios: Waste:Fe.sub.3 O.sub.4 (magnetite):50% concentration H.sub.3 PO.sub.4 solution=30:15:55 and 40:10:50. The powder mixture of waste and magnetite was mixed with a solution of 50% concentration orthophosphoric acid solution and Fe.sub.2 O.sub.3 (80 g/l ) and put into 50 ml plastic beakers. The hardening of the slurry was continued during 4-5 hours. The leaching data for radioactive and toxic elements for the final samples that were cured for 28 days are given in Table 5 (The MCC-1 static monolithic leach test) and in Table 6 (the PCT static leach test). TABLE 5 ______________________________________ Waste loading, % 30 40 ______________________________________ Normalized release Cr &lt;0.052 &lt;0.037 rate, g/m.sup.2 /day Ce &lt;0.051 &lt;0.037 ______________________________________ TABLE 6 ______________________________________ Waste loading, Normalized release rate, g/m.sup.2 /day % Hg Ce Cs Cd Cr Pb Ni ______________________________________ 30 0.222 &lt;0.034 0.11 0.011 &lt;0.0036 &lt;0.0014 0.021 40 0.151 &lt;0.026 0.24 0.006 &lt;0.0027 &lt;0.0019 0.015 ______________________________________ After curing for 28 days, the characteristics of the cements samples have been identified. The characteristics are summarized in Table 7. TABLE 7 ______________________________________ Waste loading, mass % 30 40 ______________________________________ Density, g/cm.sup.3 1.63 1.67 Weight loss, wt. % 1.95 2.13 Compressive strength, psi 1050 2700 ______________________________________ Although the invention has been described in detail with respect to preferred embodiments thereof, it will be apparent to those skilled in the art that variations and modifications can be effected in these embodiments without departing from the spirit and scope of the invention.