Microwave Vitrification of Hazardous Sludge by Şırnak Asphaltite Slime, Shale and Sewage Sludge – Landfill Management by Vitrified Char Sand

Abstract

Mazıdağı Etibakır Cu ore leaching waste stockpiles, land soil and groundwater in the field should be controlled for seepages to avoid the acidic flow of solute containing the heavy metals of Pb, Cu and Zn. The heavy metal-associated liquor from Electrowinning Plant and Sulphuric acid Dissolution units threats the neighborhood in the town. Cu and Co are recovered by electrolysis and acidic solutions of Cu leaching are spent. According to this concern of waste management, a method commonly used, “vitrification of sludge,” among others such as special cementing or bituminous pasting may be used in the waste disposal and even ground stabilization. However, mixing that with glassy powder and further vitrification furnace heating yield a vitrified form of waste sludge, covered by glazed matter avoiding contact with water in the landfill. In this study, sodium silicate is used as a binder in the vitrification mixture with the sludge at 14% water under microwave radiation. The dissolved contents of Pb Zn and Fe in the yielded vitrified briquette are determined. Additionally, the strength of vitrified briquettes is investigated in terms of vitrification parameters of microwave radiation.

1. Introduction

The disposal of hazardous sludge is much significant in landfill waste management, covering and dumping. The reactive chemistry of sludge threats ecology even in a landfill [1, 2, 3, 4]. There are many hazardous wastes such as the muddy by-product from the heat-treated steel manufacturing with CN baths [1, 2, 3, 4], textile painting [1, 2, 3, 4] and tanning sludge metal peroxide salts [5, 6], radioactive fuel waste sludge [7, 8], heavy peat of pulp washing industry [1, 2, 3, 4].

The runoff mine phosphate ores are calcined for the production of reactive phosphate compound before conversion of phosphoric acid in the production of superphosphate fertilizer in Mazıdağı Etibakır Plant [9, 10]. However, the Cu ores from Küre and Şirvan are transferred to Mazıdağı Etibakır Cu ore stockpiles field and dissociated from Electrowinning Plant and Sulphuric acid Dissolution units. Cu is recovered by electrolysis and spent acid solutions of dissolution and electrowinning are decanted and sludge effluent is collected in the two different tailing ponds [1, 2, 3, 4]. Under the atmospheric conditions of hard wintertime, during the time of heavy raining months in Mazıdağı, Mardin province of Southeast Anatolian Region, phosphate plant production facilities located need clean irrigation water and a hundred meter away, the freshwater reservoir of Mazıdağı town is located. The economical value of this reservoir reduces the cost of living, agricultural irrigation and animal farming in the town with a low population of about 7400 [1, 2, 3, 4]. Effective wastewater management of high capacity of Cu dissolution plant will not threaten the scarce freshwater potential of the town and provide the much clean ecology. The spent sludge of sulfuric acid in Cu leaching is advantageous for the Co recovery process. There is a resulting heavy sludge waste of electrolysis rich with Fe, Pb, Cd and Zn. This black metal sludge is used for extraction of metals such as Au and Co. However, the recycling dissolution results in a high solute level of Pb, Hg Zn, Cd and Fe during recovering Co. This vitrification method provided a new idea for the hazardous sludge disposal in recycling plants with char/coal slime use by sludge waste.

In this study, the sludge samples of tailing ponds 1 and 2 were economically heated by microwave oven as briquettes of 50 mm size homogenously mixed with sodium silicate in the 16% porous structure and even Şırnak asphaltite slime mixed reduces metal contamination in the wet sludge of the tailing ponds. The development of compaction stress reduces the porosity of briquettes and provides a much higher strength for vitrified block formation and much possible inert-vitrified briquette yield for landfilling. Particularly in this study, the Şırnak asphaltite slimes and oak wood char subjected to the fine screening under 0.2 mm and carbon ability over Pb and Fe contamination were investigated as weight rate.

1.1 Hazardous acidic leaching waste sludges

Neutralization of acidic waste effluents is washed, and settled precipitated metal sulfates and lime iron hydrates form sludge in the oxide micron-sized hydrates in a muddy state. However, the filtrated matter containing the sulfate part of the reaction [7, 8, 9] may cause redox effect oxidation. Then

$${\mathrm{H}}_2\mathrm{S}+{\text{4H}}_2\mathrm{O}\to {{\mathrm{SO}}_4}^{2-}+10{\mathrm{H}}^{+}+{\text{8e}}^{-}.$$E1

$$\mathrm{PbS}+{\text{2Fe}}^{3+}+{{\text{3SO}}_4}^{2-}\sim +3/{\text{2O}}_2+{\mathrm{H}}_2\mathrm{O}\to {\text{PbSO}}_4+{\text{2Fe}}^{2+}+{\text{2H}}^{4+}+{\text{3SO4}}^{2-}.$$E2

$$\mathrm{ZnS}+{\text{2Fe}}^{3+}+{{\text{3SO}}_4}^{2-}\sim +3/{\text{2O}}_2+{\mathrm{H}}_2\mathrm{O}\to {\text{ZnSO}}_4+{\text{2Fe}}^{2+}+{\text{2H}}^{4+}+{\text{3SO4}}^{2-}.$$E3

The heavy metal contents such as Pb and Hg are dissolved in the use of lower pH acidic solutions of H2SO4 or HNO3 in the electrolysis mud recycling leaching end as regards Pb heavy metal contamination is followed by equation, where ${\mathrm{HNO}}_3^{-2}$ nitrate concentration in the effluent

$$\frac{{\mathit{dc}}_{\mathit{Pb}}}{\mathit{dt}}=k_i{c}^{\mathit{tin}}.\mathit{dc}.f_i{\left({\mathit{HNO}}_3^{-2}\right)}^{\mathit{tin}}$$E4

$$\begin{array}{c}\text{2CaO}({\mathrm{Fe}}_2{\mathrm{O}}_3/{\mathrm{Al}}_2{\mathrm{O}}_3.\mathrm{MgO}{\mathrm{Si}}_8{\mathrm{O}}_{20}{\left(\mathrm{OH}\right)}_4.{\mathrm{nH}}_2\mathrm{O}+{\text{2NaS}}_2{{\mathrm{O}}_4}^{2-}+{\text{2H}}_2\mathrm{O}\\ \leftrightarrow \text{2NaCaO}(\mathrm{FeO}{\mathrm{Fe}}_2{\mathrm{O}}_{3.}{\mathrm{Al}}_2{\mathrm{O}}_3\mathrm{MgO}.{\mathrm{Si}}_8{\mathrm{O}}_{20}{\left(\mathrm{OH}\right)}_4.{\mathrm{nH}}_2\mathrm{O}+{{\mathrm{SO}}_3}^{2-}+{\text{4H}}^{+}\end{array}$$E5

$$\text{Clay}-{\mathrm{Fe}}^{3+}+\text{4NO}3/{{\mathrm{SO}}_4}^{2-}\leftrightarrow \text{Clay}-\text{Ferrous}+{\text{2S}}_2{{\mathrm{O}}_4}^{2-}+{\mathrm{H}}_2\mathrm{O}\to {{\text{2SO}}_3}^{2-}+{\mathrm{S}}_2{{\mathrm{O}}_3}^{2-}+{\text{2H}}^{+}$$E6

$${\mathrm{Fe}}^{2+}+\mathrm{Pb}/\mathrm{Zn}/{{\mathrm{MnO}}_4}^{2-}+{\mathrm{HNO}}_3+4{\mathrm{H}}_2\mathrm{O}\to \left({\mathrm{Fe}}_{\mathrm{X}}{\text{2Cr}}_{1-\mathrm{x}}\right){\left(\mathrm{OH}\right)}_3+\text{5OH}-$$E7

The dissolution kinetics of soil mud particle for Pb, MnO₂ heavy metal is followed by Eq. (7)

where CPb, CaO, MnO₂ dissolution mg/l, k the rate of digesting of lead, i is the reaction style, t is time.

The digesting amount of heavy metal in aliquate of solute of tailing pond as regarding sludge contamination is managed by equation, where n is the kinetic order type as given below

$$\frac{{\mathit{dc}}_{\mathit{\text{ACaO}}}}{\mathit{dt}}=k_i{c}^{\mathit{tPb}}\mathit{dc}$$E8

İndustrial hazardous waste effluents threaten the agricultural land and freshwater reservoirs in a high-risk concern with relationship between the collection of wastewater through the sewage network of urbanization, the hazardous sludge treatment, transmission to decantation, disposal treatment and discharge style. Hazardous sludge and effluent management with projection on neutralization and decantation never avoid the harmful end of the sewage output, and toxic substances still exist. Regarding hydroelectricity dams, animal farming freshwater lakes are located near highly populated cities, where water management taxes, loans and low-interest loans use discounts as well as other financial support mechanisms. Hazardous sludge and effluent discharge management are so much extra critical in the way of financial consideration for public health and ecology [10, 11, 12, 13, 14, 15].

1.2 Hazardous sludge

The industrial effluents with hazardous sludges are subjected to clean filtering in a continuous flow system. The hazardous effluent is decanted and followed to a best sorption process and the resulted sludge of sorption and filtered neutralization sludges show that a high amount of lime and hazardous metal salts are suitable for the vitrification of hazardous sludges for disposal. At landfill areas, the vitrified products should protect their form without cracking and digesting the hazardous content down to the irrigation or freshwater limits defined by the ecology legislation, with mg/l metal Fe.

The Fe analyses were performed with the sludge original samples and vitrified samples of different weight rate vitrifying binder to determine the duration period as leaching kinetics of Fe and Zn metals on the dissolved briquettes. The results show that Fe oxides, hydroxides, sulfates, Zn oxides, hydroxides and carbonates sulfates were dependent on ion exchange ability with lime Ca, the Zn retention occurs by crystallization as hydrozincite, and Zn₅(OH)^–(CO₃)^2– and ferric hydroxide crystallizes on neutralization sludge lime coated as ferric hydrate /zinc oxide hydrocarbonate. However, Pb sulfate and hydroxide cover are also observed in the sludges at less rates depending on the electropotential of pH values over porosity of sludge formed from clusters of ferric iron oxide and lime solids (Table 1) [16].

Material	Alkali leaching solution	Solubility constant, logK
Quartz	NH4/Na/KOH+UO2= KO2UO2 + 2H+; Na/KOH+UO2= KO^.UO2 + 2H+; Na/KOH+UO2= KO^.UO2 + 2H+; Ca/Fe(OH)2+UO2= KO2^.UO2 + 2H+; NH4/Na/KOH+UO2= KO2UO2 + 2H+; NH4/Fe(OH)2+UO2= KO2^.UO2 + 2H+; NH4/Fe(OH)2+UO2= KO2^.UO2 + 2H+; NH4/Fe(OH)2+UO2+HCO3= KO2^.UO2 + 2H+; NH4/Fe(OH)2+UO2+HCO3= KO2^.UO2 + 2H+	–5.5
Chlorite		–4.7
Muscovite		–5.75
		–0.55
Albite		–1.5
Ferrihydrite		–0.32
Limonite		–0.62
Ferrihydrite		–0.62
Limonite		–0.42

Table 1.

Values of samples at thermal dissolution [16] over 100^oC.

Sulfite oxidation kinetic rate is developed as given below Eq. (9),

$$\mathrm{r}=\mathrm{k}\sqrt{S/}{\left(\mathit{SO}3\right)}^{2-}\left\{{\left(\mathrm{O}\right)}^{2-}-{\left[{\left(\mathrm{O}\right)}^{2-}/{\left(\mathit{SO}3\right)}^{2-}{K}_{\mathit{sol}}\right]}^2\right\},$$E9

where K_sol is dissolution equilibrium constant, and SO₃^2– and O^2– solute concentrations of sulfite and oxygen are dissolved.

The mass diffusion of cracked bonds of hydrocarbon aromatic apolar reactive sites raises the kinetic rate of dissolution through porous coal texture, while asphaltite massive texture avoids the dissolution.

Specification and sorption for risk assessment, [17, 18, 19] modeling and application for hazardous waste management should be considered over legitimate rules regarding:

radioactive decay

complexation reactions; hydrolysis, dissociations, association polymerization, oxidation redox reactions may cover hazardous components in those reactions

precipitation

co-precipitation, inclusions, surface precipitation

physical and chemical sorption on surface

formative solids

ion exchange

extraction

colloid formation

biosorption

1.3 Vitrification silicate

The microwave vitrification studies of Cu, Zn, Pb and Fe were conducted on tailing pond sludges of pools 1 and 2 of Mazıdağı Etibakır Cu recovery plant to determine the efficiency of briquetting and strength of blocks. The resulted blocks are in the form of vitrified conventional heating and microwave heating during retention time. The melting capacity of Na silicate for these sludges commonly presents the dissolution ability in the landfill area.

The window glass production technology includes the crushing-grinding, screening, washing and sand flotation unit following a very fine 200 micron and Fe % grade of sand decreased to below 0.5%, while vitrification does not need clean sand, and even dirty recycled glass waste is evaluated [20, 21, 22, 23]. Thus, to provide vitrified matter, the cement retort kiln or firing grate furnace produces sintered waste material, homogeneous, vitrified and suitable landfill slag material. The suitable slag by-product without landfilling can be used as aggregate in asphalt road pavement and masonry stone production with low costs. Asphalt pasting of hazardous sludges is also becoming another covering method to avoid heavy metal contamination [24, 25, 26, 27, 28]. Şırnak asphaltite slime is already below 100-micron size and so easily mixed to cover sludge in microwave radiation. The recycled bottle waste glass and the broken window should be easily evaluated as aggregate. The shale waste of Şırnak asphaltite coal quarries reaching over 7 million tons may be evaluated as vitrification binder following grinding [29]. This vitrifying method costs less. In this study, negative effects on the vitrification quality and capacity are determined. Şırnak asphaltite slime properties are also important for vitrified briquette breakage and porosity, and surface area change.

Instead of the use of conventional grate firing, microwave vitrification is becoming advantageous in internal surface covering by inner volume heating by radiation of sludge fine solids mixed with Na silicate fine and coal slimes avoiding contamination.

1.4 Microwave heating

Microwave radiation conducts the waves through the material as radio wave frequency in tri-band microwave frequency (UHF: 300 MHz to 3 GHz), super high frequency (SHF: 3 GHz and 30 GHz) and extremely high frequency (EHF 30 GHz to 300 GHz) [11]. The microwaves pass through the whole inner depth of the diamagnetic solid texture [30, 31, 32, 33, 34]. The iron oxides such as wustite, magnetite and hematite can be heated in 20–30 sec at 2–3 mm size, while plastic materials isolate the waves [31]. The metallic salts such as Pb and Zn oxide or semi-metallic sulfides behave similarly as ferrous solids with high emissivity ın electromagnetic energy [32], in which solid temperature increases the temperature of whole sample volume, unlike conventional heating [33, 34].

Mineral packed in solid-densed form is easily heated under the radiation of microwave with high-frequency vibrations of inner atomic layers in mineral crystal and thermal energy increase conducts the heat from core to surface of particle grain. The heat-covered surface raises the temperature and creates an effect of melting of surface and sintering particles in the microwave vitrification of oxide solids. The studies showed that iron-bearing ores, roasting of sulfides, refractory gold concentrate oxidation, and activated carbon regeneration can be accomplished by microwave radiation in the shortest time periods between 30 sec. and 3 min [31]. The microwave heating slightly affects the calcination of limestone rock in 30 min.

Microwave act on minerals was determined to be sufficient [33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43]. Microwave interaction parameters on mineral crystals, microwave penetration level, the vibration of mineral grains, grain boundary heating, and heat absorption were managed. The thermal effects vary according to microwave-radiated mineral species [44]. The least penetration of mineral grains of quartz is given in Table 2 and has 79^oC a temperature change.

Mineral type	Maximum temperature, ^oC	Time, min
Albite	69	7
Chromite	155	7
Chalcopyrite	920	1
Cinabarite	144	8,5
Galenite	956	7
Hematite	1082	7
Magnetite	1258	2,75
Marble	74	4,25
Molibdenite	192	7
Ortochlase	67	7
Pyrite	1019	6.75
Pyhrotite	586	1.75
Quartz	79	7
Sphalerite	88	7
Zircon	52	7

Table 2.

Microwave temperature effect on minerals [45].

Quality of vitrified briquettes—efficiency of vitrification.

High-intensity microwave radiation provides high-thermal inner particle surface melting Na silicate over 300^oC such as low-temperature glazing. The microwave act as a sintering bound of particles of hazardous oxide and sulfate salts of dissolved sludge with heavy metals such as Pb, Cu, Zn, Fe. The vitrified glassy product contains 16–12% Na coming from melting Na silicate behaving highly transparent liquid interactive conduction heating. A high duration period will also recrystallize Na silicate binding phase. The strength of briquettes will be reduced by breaking the act of lime and Ca hydrates, and carbonates. The addition of Şırnak asphaltite slime and Şırnak shale as clay stone fines was examined in this study. The effect of microwave radiation on vitrification ability and the qualities of briquettes of this mixture was investigated.

Industrial hazardous sludges and wastewater effluents from the metal coating, Zn-galvanizing effluents and other hydrometallurgical processes generally contained high levels of heavy metals such as Pb, Zn, Cr, Hg, Cd, Fe [46, 47, 48]. The vitrified matter encapsulates this hazardous salty solid-precipitated matter in a mixture of bound silicate cover. Hence, the hazard of heavy metal dissolution is avoided. The dissolution of vitrified heavy metal salts shows the quality of vitrification. Current encapsulation technology is also advantageous for radioactive sludge However, the other methods following precipitation, ionic exchange and covering or melting in synthetic resins, plastics require high-cost processing and operational costs even still create waste disposal issues. The vitrification method is usually capable of proving the limits of legislation of below 0.1 and 3 mg/l for Pb, Zn, Cd and Cd metal values [49, 50, 51]. The hazardous metal precipitation is not sufficient in neutralization and decantation down to the legal limits because organic and inorganic complex compounds allowed effluent levels above those regarding the solubility of the metal hydroxides [52, 53, 54, 55, 56, 57]. Recycling of heavy metals based on vitrification may also be suggested as an alternative approach.

2. Methods

The studied waste deposit tailing ponds cover a surface area of approximately 9 decares, and they are 3 m deep at the northeast disposal area, and lowering 3–5 m deep at the eastern Mazıdağı water reservoir end. It is estimated that a total 1–0.5 million tonnes of hazardous leaching ferrite slime wastes are deposited from adjacent sulfuric acid unit that is grayish-black in color, and now found mostly in the north part of the Mazıdağ Etibakır plants. Groundwater investigation was carried out by 5 boreholes drilled 2-meter depth in the sludge slime deposit and 15 samples were collected at 1 m and 2 m depth from the muds for the analysis of pH, electrical conductivity, leachable Pb, Fe, Zn, Cu, Cd and SO₄. Table 3 gives the chemical analysis taken from ponds 1 and 2.

The amount of binder is investigated in the strength of briquetted blocks at 10-mm cubic forms as reported on different weight rates of sludge waste. The contamination characteristics in 1 M HCl and H₂SO₄ soluble acid solutions are investigated with standard wastewater tests over the resulted effluents at the end of 1-h boiling. The sludge below <150-micron size is mixed with the sodium silicate sand fraction (–0.6mm + 150 microns) by microwave melting.

The Pb, Fe and Zn metal cations studied were sludge effluents were analyzed UV spectrophotometer from calibrated standards of 1–100 mg/l and leaching was carried out using HNO₃ 5N for a leaching period of 1 h with 75 ml of solution in the microwave. The sludge samples received from Mazıdağı are subjected analyses. The metal values of sludge in effluent analyses showed that sludge had 130 mg/l for Zn and 325 mg/l for Fe and 28 mg/l for Pb at pH: 5–6, 15% wet solute content.

Batch flasks using 10 gr solid samples dried as sludge slime were dried in the microwave oven at 10 minutes and then settled in 10-mm-diameter steel molds and compressed under 2-ton loading. The Na silicate mixed sample mixtures by Ermenek lignite/Şırnak asphaltite/Gediz lignite slime, shale and hazardous sludge to homogenization mixer in the experiments.

2.1 Particle size distribution: asphaltite slime/lignite slimes

This compost is especially sorbent used wastewater treatment. The fly ash compost granules are used as hazardous industrial wastewaters and the sorbent types and desirable properties of activated and cleaned sorbents in the experiments are given in Table 4 and chemistry is given in Table 5 for geothermal waters used in neutralization.

Effluent, mg/l	Pond 1	Pond 2	Sludge1	Sludge2	Groundwater well
Hg	8.11	4.71	52.3	74.11	4.71
Pb	10.58	14.53	73.2	128.58	11.53
Fe%	4.33	7.62	5.91	9.3	0.52
K+Na	227.52	338.46	1328.7	1748.52	58.6
Cd	24.72	19.56	144.1	184.72	19.56
Mn	33.3	24.1	274.2	463.3	24.1
Cu	27.2	30.2	715.7	997.2	10.2
As	31.10	22.44	92.8	232.10	2.44
SO4%	4.57	9.37	5.9	8.67	0.45

Table 3.

The compositions of sludge samples of Mazıdağı Etibakır Leaching Plant Tailing Ponds.

Sample	Şırnak asphaltite slime	Ermenek lignite slime	Gediz lignite slime	Oak wood char	Şırnak coal shale
SiO2	23.53	19.42	14.14	0.1	17.53
Al203	10.23	6.53	12.61	0.1	13.61
Fe2O3	14.59	8.48	7.34	0.1	9.67
CaO	16.48	11.23	10.18		19.48
MgO	5.20	5.28	4.77	0.1	4.28
K2O	4.41	2.53	3.22	0.2	2.51
Na2O	3.35	2.24	1.71	0.1	2.35
Ignition loss	26.19	50.11	36.43	60.9	26.09
C/H/S	39.32	59.21	42.20	99	9.67

Table 4.

The ash chemical analysis values of vitrification mixture filling materials of Şırnak province and lignite slimes.

Coal type	Şırnak asphaltite slime	Ermenek lignite slime	Gediz lignite slime	Oak wood
C	20.3	42	29	24
H	2.0	2.1	2.3	2
S	6.1	2,2	3.6	0.2
Ash	67.7	24	33	0.7
Moisture	1.9	24	29	72

Table 5.

The elemental analysis values of vitrification carbon mixture filling materials, Şırnak asphaltite slime, lignite.

M is mass of aggregate is, the void is affected by compaction of briquetting and binder distribution, and especially, melted asphalt and polymer distribution are controlled by volume % of compaction. The bulk elasticity will also be controlled by the amount of polymer-bound as a volume.where, γg=_density of aggregate, g/cm3; V(r) and dN(r) are the volume and particle amount of aggregate in the size region of integration of cumulative pile from r, to r+dr), respectively. Vr volumetric equation is,

$$\mathit{dMr}=\mathrm{\gamma }g\mathrm{V}\left(\mathrm{r}\right)\mathrm{dN}\left(\mathrm{r}\right)$$E10

$$V\left(\mathrm{r}\right)=k{r}^3$$E11

where k is the shape factor.

Slime particle size distribution

Particle size distribution is defined by aggregate crushing matter,

$$\mathrm{u}\left(\mathrm{x},{\mathrm{d}}_{\mathrm{f}},\mathrm{c}\right)=\left(\chi /{\mathrm{d}}_{\mathrm{f}}\right){\left(1+\mathrm{k}/{\mathrm{d}}_{\mathrm{f}}\left(\mathrm{x}-\mathrm{\chi }\right)\right)}^{-1/\mathrm{k}}$$E12

$$\mathit{Rss}\left(n\right)=f\left(n\right)\mathit{xW}\left(n\right)\sum _{m=1}^{n}1/{\left(1-r\right)}^m$$E13

2.2 Briquetting of mixture prior to vitrification

The mixed slime and sludge with Na silicate and Şırnak asphaltite slime microwave heated following pressing in 50-mm mold under 3-tons load. The squeezed matter reduced wet solute at a 10% weight rate. The surface area and porosity are measured by the Rigden flow meter in this work. It is generally used for cement surface area measurement. This slime and sludge mixing nearly had a low surface area, as measured by the single-point BET N₂ adsorption method, of 11 m²/g. Sludge used was at a particle size < 0.1 mm for vitrification and ranging below 0.2 and 1 mm for Şırnak asphaltite slime and Şırnak shale.

Figure 1 shows the slime sample fineness and size distribution as solid sludge compost increasing the compaction ability and even fine homogenous mixing. Figure 2 illustrates the compaction ability of sludge compost under a loading press of 20 kN at size 10 mm diameters.

Figure 1.

The ash and Şırnak asphaltite slime distribution regarding void in gradation in ASTM standard.

Figure 2.

The compaction limits of sludge regarding void in fineness gradation.

3. Results and discussions

3.1 Microwave-vitrified matter

The collected sludges were analyzed by XRD and the chemical analysis results show that high ferric oxide and ferrous sulfur, over 83% with 9% wet weight rate the rest was carbonate hydrates consisting mainly of sillimanite (ZnCO3H2O), Zn-cupric carbonates such as malachite FexZnyCuy CO3H2O, Zn-ferrous hydrate (Zn, Cu) FeSO4 H2O, gypsium (CaSO4 2H2O) and chalcanthite (CuS045H20). Their chemical oxide and hydrate distribution are given in Tables 6 and 7.

Mixture components	Binder+Sludge1	Şırnak asphaltite slime+oak wood char+ sludge1/2	Ermenek lignite + oak wood char + sludge 1/2	Gediz lignite +oak wood char+ sludge 1/2
Na2Si2O6	15
Fe2O3	4	42	29	24
PbO	7	2.1	2.3	2
ZnO	2	2.2	3.6	0.2
CaO	17	24	33	0.7
MgO	2	24	29	72
Zn/Cu ferri hydrate	4	42	29	24
Al2O3	11	2.1	2.3	2
SiO2	22	2.2	3.6	0.2
Na+K	5	24	33	0.7
SO4	4	24	29	72
H2O	12
C
Total	99

Table 6.

The chemical analysis values of vitrification carbon mixture-filling materials: Şırnak asphaltite slime and lignite of lime sludge.

Vitrified components	Binder+Sludge2	Şırnak asphaltite slime+oak wood char	Ermenek lignite + oak wood char	Gediz lignite +oak wood char
Na2Si2O6	15
ZnCO3/CuCO3	6	42	29	24
Fe2O3	40	2.1	2.3	2
PbO	7	2.2	3.6	0.2
ZnO/CuO SiO2	10	24	33	0.7
CaO	10	24	29	72
MgO	2	42	29	24
Zn/Cu ferrite	4	2.1	2.3	2
FeSO4	1	2.2	3.6	0.2
CaSO4	2	24	33	0.7
Na+K	5	24	29	72
SO4	5		29
H2O	12		2.3
C		23.5	43.6	34
Total	99	99	99	99

Table 7.

The chemical analysis values of vitrification carbon mixture filling materials: Şırnak asphaltite slime and lignite of salty sludge.

The mixed slime and sludge with Na silicate and Şırnak asphaltite briquettes comprised that below composition.

The chemical change irons in iron sulfates into the sludge contacted binder to salt phases easily melted by salt fluxing effect with Na silicate. However, sintering iron silicate and lead silicate melts occurred in the sludge vitrification end. The zinc and copper ferrite bounds to Na silicate melts present whisker style needle-like fillings in the briquette texture. The dominant spherical sludge lime hydrates and iron sulfates are not completely wetted by binder Na silicate causing weakness in the briquette structure. The dissolved iron amount relatively changed to below 6% in final vitrified matter dissolution (Figure 3).

Figure 3.

The ash and Şırnak asphaltite slime RRS distribution regarding gradation factor in 0.45 sieve.

Gypsum is generally looks like lamella morphology, and frequently presents as plate layer formings adhering close to residual ferric iron oxide. The compacted briquette strength increased by binder addition of 15% till continued to 20% weight rate as illustrated in Figure 4.

Figure 4.

The ash and Şırnak asphaltite slime RRS distribution regarding gradation factor in 0.45 sieve.

3.2 Acid digestion of vitrified matter

Lead sulfate salts over lime hydrate surface in the vitrified matrix as solid is dissolved in 1 N HNO₃ and 1 M H₂SO₄ solution on digestion bath of 100-ml flasks at 30-minute boiling period. The heavy metals such as Pb Zn and Fe hydroxides replace CaO until the solution reaches the composition expected for the equilibrium of FeSO₄ nH₂O /PbSO₄ nH₂O or ZnCO₃ .n H₂O/ CuCO₃ .n H₂O/CdCO₃.n H₂O.

Higher dissolved Cd/Zn in the effluent caused Zn carbonate precipitation in the sludge with iron sulfa-hydroxide. The surface solid of over lime was high oxidation potential, while solute concentrate of Fe was high for inhibiting precipitation as the second phase of the sorption process. This process involves mixed heavy metal precipitation followed by slow formation of microcrystalline dirty solids solute.

These tests also showed that microwave melting or sintering sludge mud in briquetted form provided much more heat effect on the sand matter with less amount of weight rate of 12% and highly reactive and dissolving Pb and iron amount reduced to 1 and 3.2 mg/l in the porosity of briquetted sludge at 16% in the vitrified matter dissolution.

Toxic intermediates may be sorped by char and shale clay may be generated precipitation heavy metals as organic complexes from barrier-integrity vitrification, effective silicate barriers and homogenous mixing with active carbon were found to be quite difficult due to surface wetting manner of carbon.

The microwave digestion with 1M acid hot solutions avoided disposal of hazardous sludge to landfill following decantation techniques in paste thickeners used flocculants, polyelectrolytes, chelants, inorganic acids or surfactants related to sludge particle size and type. The compaction porosity decreased by solvent use in compaction to 5 % under loading as shown in Figure 5.

Figure 5.

The optimum binder porosity of compost by increased solvent use as volume weight of the briquette containing 1% kerosene.

The microwave vitrification of industrial waste slurries and hazardous sludge creates a safe working environment while absorbant fly ash is used. The neutralization of hazardous slurries with fly ash vitrification treatment needs just Na silicate as a binder at a 10% weight rate for hazardous sludge of the Mazıdağı Plant of more than 220,000 tons/year.

3.3 Microwave dissolution of vitrified sludge

This work was carried out a leaching method of hazardous sludges under microwave-radiated digestion of vitrified product briquette of Şırnak asphaltite and shale mixture for heavy metal sorption and reduction following vitrification. Şırnak fly ash, coal char and the shale may be used in vitrification as absorbant even improves low acidic digestion.

To evaluate the impact of shale on five different size fractions of the treatment with microwave and heated for 3 minutes at 500^oC Sirnak shale samples, vitrified briquette dissolution and fe dissolution rate were determined as % the rate of vitrified matter as the efficiency of vitrification success by weight of briquette.

Dissolved Fe concentrates of sludges in the microwave interaction are illustrated in Figure 6 as the Şırnak asphaltite slime and wood char from below 0.5 mm size fraction was observed.

Figure 6.

The dissolution of Fe and Pb content-maximum ppm at 1L volume effluent, 10g weight of the briquette sample containing 15 solid rate digestions.

The compaction of sludge at 15% wetness is becoming advantageous as mentioned below:

• wet compaction provides the prompted compaction sliding of wet liquid by adhesing the solid matter over the wetness of 15% grade,

• compaction loading extrusion molds, where the high-load intrusion to helical drive the forming rope style briquettes,

• Microwave treatment or polymer extrusion at a high temperature of at least 200^oC in sludges to be able drive extrusion,

• Less operating and control cost during extrusion.

Oxide melting ability was so effective in metal silicate formation manner. The lower-temperature activities of metal salts also improve melted metal silicate crystallization as efficient criteria in the vitrification hazard glazing of sludge grains including certain salt content. The oxidation and digestion effect of vitrified sludge briquette in nitric acid solution is seen in Figure 6.

As seen in Figure 6, the 5 N HNO₃ solutions show the contamination change, high level precipitated suspensions obtained using the precipitation-siphoning technique, depending on the salt concentration added at 10 g-100 mg.

4. Conclusions

The slag type and fluxing matter of vitrified Na silicate waste briquettes may be evaluated as aggregates in concrete or as filler in masonry products or as concrete debris use in foundations. The special vitrified waste briquettes may be evaluated in colored glass bottle production.

The phosphate-contained vitrified matters may be evaluated in the green house sands or as sand in the soil remediation of the local agricultural land. In the landfill deposition for hazardous-type wastes with weak vitrified sludges, avoiding costing of disposal asphalt or bituminous tar type binding is beneficial for inhibiting to solute contact in the waste dumping so that decaying with acidic solutions or digesting of sludge associated with environmental act is not permitted.

Basic Na silicate vitrification by 15% weight rate is sufficient for vitrification of acidic waste sludges with a filling carbon source in a weight rate of 15%. The carbon source of asphaltite slime and oak wood char decrease the digestion of heavy metals into the nitric acid solution from vitrified texture. The longer vitrification time over 30 minutes produced better strength of over 40 MPa compressive strength for 15% Na silicate added hazardous sludge and 15% carbon filler source of Şırnak asphaltite slime.

Following 900 W microwave radiation at 20–22 min type microwave laboratory equipment, the strength of vitrified briquettes as the quality was tested. The strength increased from original values of 22 MPa to 10, 4 and 1% for Şırnak asphaltite slime, Şırnak shale and Sewage sludge. The sufficient microwave duration of 30 min showed a much efficient sintering method for hazardous sludge vitrification as designed.

Zn is decomposed as the original form of Zn₅(OH) 2(CO3) on vitrification grain surface to Na ZnO silicate form causing higher strength evolution and dissolution process is negligible, bearing in acid-digesting medium.

Heap leaching applications for gold and copper productions in the area are used for planning the feasibility reports regarding environmental contamination showing some degree of contamination and certain collection pools and seepage area will be highly contaminated by atmospherical dry conditions. In the pH measurements made, the pH value of 5.3–6.3 in washing hazardous waste sludges finally at the last washing pound to 6.3, depending on the sulfate and heavy metal of salt sludge content, was observed.

Soil washing and chelate-decayed solvents tend to destroy the soil profile and should be performed to recover metals from heavily polluted industrial sites and in case, no other methods can be applied. In situ tar or asphalt barrier layers near the aquifer are a very promising technique for the soil protection and the aquifer may not be toxified even sludges with toxic heavy metals.

Microwave vitrification using sodium silicate binder at 15% weight rate with 15% carbon filler decreased heavy metal flow in seepages of 5N nitric acid solutions with complete elimination to below 1ppm levels as shown reductions in Pb and Fe at 237% performance. In vitrified dissolution, effluent had the 24 ppm Fe and 5 ppm Pb values, in which Pb reduction rates of sorption at Langmuir model with 5N nitrate washed were 0.01 ppm/min.l Pb and total Fe reduction rate 0.03 ppm/min.l, respectively.