Temperature and pH Dependence of Some Metals Leaching from Fly Ash of Municipal Solid Waste

Abstract. Municipal solid waste combustion leads to concentration of various metals in the solid residue (fly ash) remaining after combustion. These metals pose serious environmental hazard and require proper handling and monitoring in order to control their harmful effects. Leachability of some metals from fly ash was examined in fly ash and Milli-Q water mixture (liquid-to-solid ratio, 100) under various temperature and pH conditions in the laboratory. The leaching experiments conducted for 24 hours showed that pH was generally more important than temperature in controlling the amount of metals leached out of the fly ash. However, at a given pH, rise in temperature led to different degree of (usually one to two fold) enhanced or reduced leaching of metals. Owing to amphoteric nature of oxides of Al, Cr, Pb and Zn, these metals often yielded typical pattern of increase and decrease in their concentrations with change in pH. The extent of leaching of Cr and Pb in our experiments suggests that decrease of pH to acidic range in the case of Pb and to neutral to acidic range for Cr over a long period of storage of fly ash at solid waste dumping site may facilitate leaching of these metals from fly ash, leading to contamination of groundwater to the level that exceeds beyond the level permitted by the environmental laws.     

Leaching mechanisms of oxyanionic metalloid and metal species in alkaline solid wastes: A review

An overview is presented on possible mechanisms that control the leaching behaviour of the oxyanion forming elements As, Cr, Mo, Sb, Se, V and W in cementituous systems and alkaline solid wastes, such as municipal solid waste incinerator bottom ash, fly ash and air pollution control residues, coal fly ash and metallurgical slags. Although the leachability of these elements generally depends on their redox state, speciation measurements are not common. Therefore, experimental observations available in the literature are combined with a summary of the thermal behaviour of these elements to assess possible redox states in freshly produced alkaline wastes, given their origin at high temperature. Possible redox reactions occurring at room temperature, on the other hand, are reviewed because these may alter the initial redox state in alkaline wastes and their leachates. In many cases, precipitation of oxyanions as a pure metalate cannot provide a satisfactory explanation for their leaching behaviour. It is therefore highly likely that adsorption and solid solution formation with common minerals in alkaline waste and cement reduce the leachate concentration of oxyanions below pure-phase solubility.     

Changes in mobility and speciation of heavy metals in clay-amended incinerator fly ash

The generation of municipal solid waste incinerator fly ash (MSWIF) has been increasing significantly over the recent past, and its disposal is problematic and costly due to high concentration of leachable heavy metals present in the material. This study explored a potential stabilization of MSWIF by blending with a natural sorbent material with low permeability, clay, and assessed the potential release of heavy metals from the stabilized mixtures under various simulated subsurface environments. The leachability of heavy metals such as Pb, Cd, Cr, Zn and Cu in the MSWIF-clay mixtures cured for 1 to 360 days was investigated by performing leaching tests and sequential chemical extractions (SCE). Leaching tests were performed at acidic, neutral and alkaline pH values. The leaching test results suggested that the natural clay could turn the MSWIF into non-hazardous material. All the MSWIF-clay mixtures demonstrated leaching behavior different from that of the original MSWIF. SCE results revealed that the acidic and reducing conditions were the most unfavorable to the immobilization of the heavy metals in the stabilized MSWIF-clay matrix. Conversely, the oxidizing and alkaline conditions were not critical to the stabilized MSWIF-clay mixtures. Apparently, clay in the mixtures could function as an adsorptive micro-barrier to retain the heavy metals within the MSWIF-clay matrices.     

Stability and leaching of cobalt smelter fly ash

The leaching behaviour of fly ash from a Co smelter situated in the Zambian Copperbelt was studied as a function of pH (5–12) using the pH-static leaching test (CEN/TS 14997). Various experimental time intervals (48 h and 168 h) were evaluated. The leaching results were combined with the ORCHESTRA modelling framework and a detailed mineralogical investigation was performed on the original FA and leached solid residues. The largest amounts of Co, Cu, Pb and Zn were leached at pH 5, generally with the lowest concentrations between pH 9 and 11 and slightly increased concentrations at pH 12. For most elements, the released concentrations were very similar after 48 h and 168 h, indicating near-equilibrium conditions in the system. Calcite, clinopyroxenes, quartz and amorphous phases predominated in the fly ash. Various metallic sulfides, alloys and the presence of Cu, Co and Zn in silicates and glass were detected using SEM/EDS and/or TEM/EDS. The leaching of metals was mainly attributed to the dissolution of metallic particles. Partial dissolution of silicate and glass fractions was assumed to significantly influence the release of Ca, Mg, Fe, K, Al and Si as well as Cu, Co and Zn. The formation of illite was suggested by the ORCHESTRA modelling to be one of the main solubility-controlling phases for major elements, whereas Co and Zn were controlled by CoO and zincite, respectively. Sorption of metals on hydrous ferric oxides was assumed to be an important attenuation mechanism, especially for the release of Pb and Cu. However, there is a high risk of Co, Cu, Pb and Zn mobility in the acidic soils around the smelter facility. Therefore, potential local options for “stabilisation” of the fly ash were evaluated on the basis of the modelling results using the PHREEQC code.     

Coal fly ash interaction with environmental fluids: Geochemical and strontium isotope results from combined column and batch leaching experiments

The major element and Sr isotope systematics and geochemistry of coal fly ash and its interactions with environmental waters were investigated using laboratory flow-through column leaching experiments (sodium carbonate, acetic acid, nitric acid) and sequential batch leaching experiments (water, acetic acid, hydrochloric acid). Column leaching of Class F fly ash samples shows rapid release of most major elements early in the leaching procedure, suggesting an association of these elements with soluble and surface bound phases. Delayed release of certain elements (e.g., Al, Fe, Si) signals gradual dissolution of more resistant silicate or glass phases as leaching continues. Strontium isotope results from both column and batch leaching experiments show a marked increase in ⁸⁷Sr/⁸⁶Sr ratio with continued leaching, yielding a total range of values from 0.7107 to 0.7138. For comparison, the isotopic composition of fluid output from a fly ash impoundment in West Virginia falls in a narrow range around 0.7124. The experimental data suggest the presence of a more resistant, highly radiogenic silicate phase that survives the combustion process and is leached after the more soluble minerals are removed. Strontium isotopic homogenization of minerals in coal does not always occur during the combustion process, despite the high temperatures encountered in the boiler. Early-released Sr tends to be isotopically uniform; thus the Sr isotopic composition of fly ash could be distinguishable from other sources and is a useful tool for quantifying the possible contribution of fly ash leaching to the total dissolved load in natural surface and ground waters.     

Leaching potential and redox transformations of arsenic and selenium in sediment microcosms with fly ash

The unintended release of coal ash to the environment is a concern due to the enrichment of contaminants such as arsenic (As) and selenium (Se) in this solid waste material. Current risk assessments of coal ash disposal focus on pH as the primary driver of leaching from coal ash. However, redox speciation of As and Se is a major factor for their mobilization potential and has received much less attention for risk assessments, particularly in disposal scenarios where coal ash will likely be exposed to microbially-driven redox gradients. The aim of this study was to demonstrate the differences of aerobic and anaerobic conditions for the leaching of As and Se from coal ash. Batch sediment-ash slurry microcosms were performed to mimic an ash spill scenario and were monitored for changes in As and Se speciation and mobilization potential. The results showed that the dissolved As concentrations were up to 50 times greater in the anaerobic microcosms relative to the aerobic microcosms during the two week incubation. This trend was consistent with As redox speciation determined by X-ray absorption spectroscopy, which indicated that 55% of the As in the solid phase at the end of the experiment was present as As(III) (a more leachable form of arsenic relative to As(V)). In the aerobic microcosms, only 13% of the As was As(III) and the rest was As(V). More than half of the Se was present as Se(IV) in the original fly ash and in the aerobic microcosms, while in the anaerobic microcosms Se was gradually transformed to less soluble Se(0) species. Likewise, dissolved Se concentrations were up to 25 times greater in the aerobic microcosms relative to anaerobic conditions. While the overall observations of As and Se mobilization potential from coal ash were consistent with expectations for aqueous and solid phase speciation of these elements, the findings directly show the relevance of these processes for coal ash disposal. These results highlight the need to select appropriate environmental parameters to include in risk assessments as well as provide potential geochemical monitoring tools through the use of dissolved Se/As ratios to determine the redox conditions of ash storage and spill sites.     

Long-term brine impacted fly ash,Part II: Mobility of major species in the ash residues

The leaching of major species from fly ash is a function of the pH of the solution in contact with the fly ash. The aim of this study was to determine the effect of the pH of the leachant on the leaching of species from the ash residues recovered after the long-term fly ash–brine interactions. Acid neutralization capacity (ANC) tests using solutions of different pH values ranging from the initial pH of the ash residues (11–12) to pH 4 were employed in the leaching experiments. The ANC tests revealed that the release of major species from the ash residues depended on the pH of the leachants except for Na and Cl, where the significant concentrations leached were independent of the solution pH. The concentrations of Al and Si in the ANC leachates were very high at pH below 6 while Ca, K, Sr, Mg and B were immediately mobilized from the brine impacted fly ash when in contact with de-ionized water, and leaching increased as the pH decreased. The concentration of SO₄ leached from the brine impacted ash residues at high pH was high, and the leaching increased with decrease in the pH of the leachant. This study shows that most of the major elements captured in the ash residues could be mobilized when in contact with aqueous solutions of various pH. This reveals that the co-disposal of fly ash and brine may not be the best practice as the major elements captured in the ash residues could leach over time.     

准格尔地区粉煤灰中镓的浸出率影响因素研究

为了粉煤灰的高附加值综合利用,采用酸浸法对准格尔地区循环流化床粉煤灰进行了镓的浸出实验研究,考察了多种因素对镓的浸出率的影响,包括粉煤灰粒度,酸的种类与浓度、酸浸温度与时间、固液比等。结果表明,提高镓的浸出率的适宜条件为:粉煤灰粒度200目,盐酸的浓度6 mol/L,酸浸温度应大于160℃,酸浸时间6 h,液固比在5∶1~6∶1之间为宜。在优选的工艺条件下,镓的浸出率可达80%以上。从粉煤灰中提取镓,使其作为一种资源加以利用,是提高粉煤灰综合利用价值的有效途径。     

Leachability of trace elements from two stabilized low lime Indian fly ashes

Fly ash is a waste by-product obtained from the burning of coal by thermal power plants for generating electricity. When bulk quantities are involved, in order to arrest the fugitive dust, it is stored wet rather than dry. Fly ash contains trace concentrations of heavy metals and other substances in sufficient quantities to be able to leach out over a period of time. In this study an attempt was made to study the leachabilities of a few selected trace metals: Cd, Cu, Cr, Mn, Pb and Zn from two different types of class F fly ashes. Emphasis is also laid on developing an alternative in order to arrest the relative leachabilities of heavy metals after amending them with suitable additives. A standard laboratory leaching test for combustion residues has been employed to study the leachabilities of these trace elements as a function of liquid to solid ratio and pH. The leachability tests were conducted on powdered fly ash samples before and after amending them suitably with the matrices lime and gypsum; they were compacted to their respective proctor densities and cured for periods of 28 and 180 days. A marked reduction in the relative leachabilities of the trace elements was observed to be present at the end of 28 days. These relative leachability values further reduced marginally when tests were performed at the end of 180 days.     

秭归地区闪长岩岩体风化壳微量元素地球化学特征

通过对秭归地区闪长岩岩体风化壳中微量元素的分布规律研究,将该风化剖面中的微量元素划分为3类。第一类包括Sc、V、Cr、Co、Ni、Cu、Zn、Zr、Hf、Nb、Ta、U、Th、Mo、W,基本属于非活动性元素,在风化过程中得以有效保留,其中U、Cr、Cu等受氧化还原条件的影响,有时呈局部富集现象,规律性不明显。第二类以Ca、Rb、Cs、Sr、Ba、Pb、Ga、Gd、Tl为代表,随着风化作用的进行而逐步从风化壳中淋失,属活动性元素。第三类以稀土元素为代表,在风化壳内部发生局部的再分配,从剖面上层随风化溶液向下淋滤亏损,到剖面中下部沉淀富集,其中重稀土元素的淋失程度大于轻稀土元素。由于母岩中斜长石的风化淋滤,Eu在氧化环境下逐渐从正异常变为负异常。Ce在地表氧化条件下很容易生成四价氧化物（方铈石）,并在表层明显富集,剖面介质中氧化还原条件的变化导致Ce的波动变化。     

Investigating the chemical stabilization of hazardous waste material (fly ash) encapsulated in Portland cement

Portland cement has been suggested as an effective stabilization (physico-chemical) method for hazardous waste. This research explored the immobilization of metals in various mixtures of Portland cement and fly ash waste sampled from coal power plant in the province of Lodz, central Poland. The stabilization of fly ash in Portland cement was investigated under a wide range of pH conditions (3–12). Leachability tests were used to determine the efficiency of the encapsulation by studying the dissolution of alkaline metals (sodium, potassium) and alkaline earth metals (calcium, magnesium). The lowest value of leached metals was obtained for ratio of ash to cement of 1:10 in a case of sodium and calcium, while ratio 1.5 gave the lowest leached effects for potassium and magnesium. The high effectiveness of solidification/stabilization process was gained in high pH values (9–11).     

Leaching behaviour of slag and fly ash from laterite nickel ore smelting (Niquelândia,Brazil)

The laterite nickel (Ni) ore smelting operation in Niquelândia (Goiás state, Brazil) produced large amounts of smelting wastes, stockpiled on dumps (slags) and in settling ponds (fly ash). In this study we present data on the chemistry, mineralogy and pH-dependent leaching behaviours of these two waste materials.Bulk chemical analyses indicated that both wastes contained significant amounts of potentially toxic elements (PTEs), with substantially higher concentrations in the case of the fly ash (up to 2.51 wt% Ni, 1870 mg/kg Cr and 488 mg/kg Co). The mineralogical investigations carried out using X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and electron microprobe (EPMA) indicated that the slag was mainly composed of silicate glass, olivine and pyroxene. In contrast, the fly ash was composed of Ni-bearing serpentine-like phases (originating from the furnace feed), Ni-bearing glass, olivine, pyroxene and spinel. The pH-dependent leaching behaviour was performed according the EU standard experimental protocol (CEN/TS 14997) in the pH range of 3–12. The leaching was highly pH-dependent for both materials, and the highest releases of PTEs occurred at pH 3. The slag generally exhibited an U-shaped leaching behaviour of the PTEs as a function of pH, and was found to release up to 48.0 mg/kg Ni, 25.6 mg/kg Cr, and 1.42 mg/kg Co. The fly ash was significantly more reactive, and exhibited its highest leaching level of PTEs between pH 3 and 7. The maximum observed release corresponded to 5750 mg/kg Ni, 4.35 mg/kg Cr, and 112 mg/kg Co. The leached Ni concentrations after 24 h of leaching in deionized water exceeded the limit for hazardous waste by more than 100x according to the EU legislation (40 mg/kg Ni). X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structures (EXAFS) spectra indicated that Ni in the fly ash is predominantly bound in a serpentine-like phase, and during the fly ash experimental alteration it was mainly released from the second shell (corresponding to the atomic distances between Ni and Si, Mg, Fe in high-temperature silicates, glass, and partially dissolved serpentine). This study shows that disposal sites for the fly ash can represent a significant source of local pollution, and direct recycling of the fly ash in the smelting technology (as currently adopted at the Barro Alto new smelter and since few years also at the Niquelândia smelter) is the best environment-friendly option for handling of fly ash in the future.     

Uranium and Multi-element Release from Orthogneiss and Granite (Austria): Experimental Approach Versus Groundwater Composition

In this study, the release of elements and in particular U from five Austrian orthogneiss and granite samples into a CO₂-bearing solution was investigated to describe the initial phase (24 h) of leaching focusing on the impact of ferrous (hydro)oxide formation. Experiments were conducted at ambient temperature by flushing CO₂:N₂ gas through the reactive solution (pH_initial?~?4.3) at a liquid:solid ratio of 10:1 with and without a reducing agent. The chemical evolution of the leaching solution was dominated by incongruent dissolution of silicates showing a parabolic kinetic behavior due to protective surface formation most likely caused by precipitation of amorphous Fe^III/Al hydroxides. However, the relative distribution of Ca, Mg and Sr in the leaching solution excellently traced the individual bulk rock composition. The mobilization of U was highly prevented under oxidizing conditions by sorption onto ferrous (hydro)oxides, which were precipitating through ongoing silicate leaching. Therefore, the leaching behavior of individual U-bearing minerals was less relevant for U release. At reducing conditions, the above elements were accumulated in the solution, although an oversaturation regarding U^IVO₂ was calculated. This indicates its inhibited formation within the experimental run time. The composition of experimental leaching solutions did not reflect analyzed groundwater compositions from investigated local rock-type aquifers indicating that reaction rate constants of siliceous rocks significantly differ between values found in nature and in the laboratory. Change in active mineral surface areas with ongoing weathering, accumulation of secondary precipitates, leached layer formation and given reaction time are key factors for distinct elemental release.     

Load Settlement Behaviour of Fly ash Mixed with Waste Sludge and Cement

One of the effective utilization strategies for fly ash and waste sludge is to use it as a fill material to raise low lying areas. Bearing capacity and settlement are the required input for the design of foundations on such fills. To determine the bearing capacity, plate load tests were carried out on the compacted beds of fly ash, fly ash-waste sludge and fly ash-waste sludge–cement. The tests were conducted by keeping 90, 95 and 100 % relative compaction, fresh and fresh submerged conditions, aged (28 days) and aged (28 days) submerged conditions as variables of the tests. The load-settlement curves were plotted for fly ash and mix blends. The minimum load was obtained for fly ash under submerged condition, further the test results show that the fly ash becomes flowable on submergence. On the other hand when the fly ash was mixed with waste sludge and cement, the load carrying capacity was found to improve to a greater extent. Test beds prepared with fly ash–cement-waste sludge under as compacted condition (fresh) show very high load carrying capacity (1600–2180 kN/m²). An analytical method has also been validated for fly ash–cement-waste sludge mix which was developed to estimate the settlement of footing resting on fly ash taking into account the pre-consolidation stresses. The non linearity of load-settlement behavior was appropriately modeled, on the basis of available plate load test data incorporated in the method. The method requires as input, the pre-consolidation stress and Young’s modulus of compacted mix of fly ash-waste sludge–cement. A comparison of load-settlement values observed in plate load tests and predicted values for the mix 47 %FA + 45 %S + 8 %C, using the proposed method shows good agreement. Hence, this relationship may also be useful to the field engineers to check the reported load-settlement values for such types of mixes in the field.     

Wechselwirkungsreaktionen Untertagedeponie-relevanter chemisch-toxischer Abfälle mit hochsalinaren Lösungen

The complex reactions between high saline solutions and toxic chemical wastes were investigated by means of laboratory experiments and geochemical modelling. The specific boundary conditions of an underground repository in salt formations were taken into account. In order to determine the chemical equilibrium compositions of the resulting solutions a new leaching procedure was developed and successfully employed with several toxic wastes. The results for a fly ash waste stemming from a glass smelting furnace are given in detail. Zinc and cadmium are the two most prominent heavy metals, that accumulate significantly in the leachates. In order to gain an insight into the complex dissolution and precipitation processes in such multi-component systems, geochemical modelling was performed using the program code EQ3/6 and the Pitzer formalism for calculating the activity coefficients. The thermodynamic database used was extended and Pitzer coefficients for Zn and Cd in high saline solutions were derived from literature data and added to the database. The results of the geochemical modelling of the investigated reactions were in good agreement with the experimental data. On this basis the maximum concentrations that can be leached from the investigated fly ash into a Mg-rich saline solution, that is typical for a salt repository in Northern Germany, are predicted to be 0,181 mol/kg H₂O zinc and 0,00317 mol/kg H₂O cadmium, respectively.     

Self-sealing isolation and immobilization: a geochemical approach to solve the environmental problem of waste acidic jarosite

Mimicking geochemical processes to solve environmental problems was implemented in dealing with waste acidic jarosite and alkaline coal fly ash. By placing these two chemically different materials adjacent to one another, a self-sealing layer was formed at the interface between both wastes, isolating and immobilizing chemical constituents in the process. A series of leaching experiments were performed on each material separately to study the release behavior of the principal constituents. Radiotracer experiments were conducted to explore diffusion and reaction of constituents such as Fe³⁺ in a combined jarosite/fly ash system. A model has been developed to simulate the coupled processes of diffusion and precipitation taking into account porosity change due to pore filling by precipitates. The formation of a self-sealing isolation layer in a hypothetical jarosite/fly ash disposal site was modelled. Leaching results indicate that the release of elements from jarosite is much larger than that from fly ash, and that the highly pH dependent release of Fe, Al, and Zn was controlled by the solubility of their hydroxides. Leaching results also suggest that precipitation reactions can be expected to occur at the interface between jarosite and alkaline coal fly ash where a large pH gradient exists. Radiotracer experiments showed that accumulation of constituents occurred at the interface. Modeled Fe³⁺ profiles in layered jarosite/fly ash were well validated by experiments. Modeling results also showed that with the accumulation of constituents at the interface, a new layer with low porosity was formed. Application of this model suggests that there is a potential use to form a self-sealing layer in jarosite/fly ash co-disposal sites.     

Leaching capabilities of iodine monochloride (ICl) and diethylenetriamine pentaacetic acid (DPTA) at different concentrations and pH for some major and trace metals from coal and coal fly ash

In the present study, coal from Chakwal (Pakistan) was leached with an aqueous solutions of iodine monochloride (ICl) and diethylenetriamine pentaacetic acid (DPTA) of different concentrations. The effect of stirring time, concentration and pH was studied on the leaching of different metals from coal. The physicochemical parameters indicated that the coal was of reasonably good quality. The results indicated that with increase in time duration, the extraction of metals increased. In most of the cases, metal concentration increased in the leachate with increasing the concentration of the leaching agents. DPTA was found to be the best leaching agent for most of the metals. Higher extraction of metals from coal fly ash indicated that coal organic matter has a pronounced effect on the leaching. Higher concentration of metals was extracted from virgin coal and coal fly ash at low pH (p?>?0.00) as compared to high pH. DPTA extracted metals in higher concentration from virgin coal and coal fly ash at low pH as compared to ICl. Based on the present study, the most leached metals were Fe, Cu, Mn and the least were Pb, Ni, Cd and Cr.     

The leaching of trace elements from municipal solid waste incinerator bottom ash at different stages of weathering

For a proper assessment of the environmental impact of the utilisation and disposal of Municipal Solid Waste Incinerator (MSWI) bottom ash it is necessary to understand weathering processes and their effects on (trace) element leaching. The authors have investigated the processes that control the leaching of Cd, Pb, Zn, Cu, and Mo from 3 categories of bottom ash: (A) unweathered bottom ash (grate siftings and unquenched samples), (B) quenched/non-carbonated bottom ash (freshly quenched and 6-week-old samples), and (C) weathered bottom ash (1.5- and 12-year-old samples). Leaching experiments were performed in a pH-stat at a large range of pH values. The speciation code MINTEQA2 was used for subsequent modelling of precipitation/dissolution processes. The speciation of trace elements in weathered bottom ash was also investigated by microanalytical techniques. In A- and B-type bottom ash the general controlling processes are thought to be precipitation/dissolution of relatively soluble minerals or, in the case of Cu in particular, extensive complexation with dissolved organic C. At the “natural” pH of the samples, the leaching of Cd, Pb, Cu, Zn and Mo is generally significantly lower from C-type bottom ash than from less weathered types of bottom ash. This reduction in leaching is due to the neutralisation of bottom ash pH and the formation of less soluble species of these elements as weathering continues. In the more weathered (C-type) bottom ash trace element leaching does not seem to be solubility-controlled; although slow precipitation reactions cannot be totally excluded, it is hypothesised that the controlling mechanism in those samples is sorption to neoformed minerals.     

近中性溶液条件下富镉铅锌矿矿石的风化淋滤实验研究

在近中性溶液条件下对富镉锌矿石进行了风化淋滤实验研究，发现淋滤液中产生大量以石膏为主要成分的沉淀物。淋滤液呈碱性，淋滤出来的Zn、Cd以水溶态和沉淀态形式存在，而以后者为主。淋滤50天后，黄铁矿闪锌矿石中Zn、Cd的淋滤率为0．03％和0．01％，而半氧化闪锌矿石Zn、Cd的淋滤率则高得多，分别0．10％和0．60％。     

碳质银精矿氯化浸出工艺的研究与应用

采用氧化焙烧工艺对碳质银精矿进行除碳、除硫预处理,试验确定焙烧温度为650℃。焙砂以3YL--NaCl无氰氯化体系浸出,研究了影响氯化浸出的因素:3YL用量、氯化钠浓度、浸出酸度、时间、温度℃及固液比等,并在试验确定的工艺条件下,进行了公斤级试验,得出Au、Ag、Cu、Pb、Zn的氯化浸出率分别为95.1%、91.6%、85.7%、95.2%、83.8%。