Initial Leaching Research Articles

Seagrass litter decomposition: an additional nutrient source to shallow coastal waters

Seagrass ecosystems are vital for its regulatory services yet, highly threatened by degradation due to human pressures. Decomposition of two tropical seagrass species (Cymodocea serrulata and Cymodocea rotundata) was studied and compared, to understand their potential in generating additional nutrients to coastal waters. Release of carbon, nitrogen and phosphorus during the decomposition process of seagrass wracks was estimated in bacteria-active (non-poisoned) and bacteria-inhibited (poisoned) conditions from shore-washed fresh seagrass, sampled from Palk Bay, India. Incubation experiments for 25days indicated a near three times higher concentration of dissolved organic carbon (DOC) in bacteria-inhibited flasks compared to bacteria-active conditions for both species. The maximum leaching rates of DOC, TDN and TDP were found to be 294, 65.1 and 11.2μM/g dry wt/day, respectively. Further, higher release of dissolved inorganic nitrogen (DIN) (> 1.3 times) was documented from the bacteria-active flask, highlighting the significance of microbial process in generating bio-available nutrients from decaying seagrass. Faster decomposition (0.014 ± 0.004day-1) in the initial stages (up to 8days) compared to the later stages (0.005 ± 0.001day-1) indicated a rapid loss of biomass carbon during the initial leaching process and its relative importance in the decomposition pathway. The decomposition rate is best described by a single-stage exponential decay model with a half-life of 41days. It is estimated that the total seagrass litter available along the Palk Bay coast is about ~ 0.3Gg with high potential of additional nitrogen (0.9 ± 0.5Mg) and phosphorus (0.3 ± 0.1Mg) supply to the adjacent coastal waters.

Characteristics of the cement-solidified municipal solid waste incineration fly ash.

Cement solidification is an important pre-treatment technology for municipal solid waste incineration (MSWI) fly ash into landfill. The physicochemical properties and leaching characteristics are the foundation for assessing the long-term stability of the fly ash solidified with benchmark cement in landfills. The leaching performances of bulk components (Na, K, Ca, Cl, CO32-, and SO42-) and heavy metals (Cu, Zn, Cr, Pb, and Zn) were analyzed based on the percolation column test and pH dependent test respectively. The research showed that in the cement-solidified fly ash, Na and K were mainly in the form of soluble chloride salts and would be washed out severely at the initial leaching stage due to the weak fixation effect of cement. Moreover, a considerable amount of Ca was washed out simultaneously with Na and K, causing a temporary increase in pH value, and then Ca leaching was controlled by the solubility of minerals, mainly calcium carbonate, ettringite formed with CO32- and SO42-. Cement solidification reduced the cumulative release of mobile Cu, Zn, Cr, Pb, and Cd contained in MSWI fly ash. In the cement-solidified fly ash, the leaching of Cu and Zn was controlled by mineral solubility under alkaline conditions, Cr was dependent on the redox conditions, and Pb was related to the complex structures formed with Si-O bonds of silicates. A further research on the long-term stability of the cement-solidified fly ash in landfills was needed.

In Vitro antibacterial activity of Ta2O5 doped glass-ceramics against pathogenic bacteria

The use of synthetic implants for restoration of damaged or diseased bone is associated with risk of bacterial colonization that result in failure of the implant. It is essential for implants to make bond with bone and soft tissue without bacterial infection. The present study is based on evaluation of the antibacterial property of Ta2O5 doped novel glass ceramics having a chemical composition (40-x) SiO2-24.4Na2O-26.9 CaO-6.1CaF2-2.6P2O5-xTa2O5 where x = 0, 0.1, 0.5, 1 and 3 mol %. In Vitro antibacterial assays were performed in dark against six common pathogenic bacterial strains; Strep. pyogenes, B. subtilis, Staph. epidermidis, E. coli, Proteus. mirabilis and Pseudomonas. aeruginosa using modified Kirby Bauer method. It was observed that all samples doped with Ta2O5 showed statistically significant (P < 0.05) antibacterial activity against all three gram positive bacteria; independent of high pH value of the supernatant. Sample doped with 3 mol% Ta2O5 demonstrated strongest antibacterial effect, which may be attributed to high concentration of Ta+5 ions observed in the supernatant (SBF). The antibacterial activity of Ta2O5 doped Glass ceramics was prone to initial leaching of high ionic strength Ta+5 ions from the specimen surface to supernatant that exerts hyper-osmotic environment which inhibited bacteria. Therefore, it can be concluded that addition of Ta2O5 to Glass ceramics exerted antibacterial ability to bioactive Glass ceramics composition.

Extraction of Vanadium from Ammonia Slag under Near-Atmospheric Conditions

A process for extracting vanadium from ammonia slag is proposed in this work, taking advantage of the nature of V5+ vanadate ions condensing into a solid phase around a pH of 2. The slag is a mixture of oxides of Ca (36.0 mass %), Si (28.4 mass %), Al (9.3 mass %), Fe (7.1 mass %), V (6.9 mass %), S (3.9 mass %), Na (2.7 mass %), Ni (2.5 mass %), Mg (1.3 mass %), and other (K, P, and Ti) (1.9 mass %). The difficulty with extraction originates from the oxyanionic character of the vanadate ions, leading to the formation of vanadate salts with the concomitant cations. In contrast, a stepwise-pH-control process that is proposed in this work is effective for separating vanadium from the slag, as (1) the Si component in the slag is filtered off as the residue at the initial leaching step; (2) Fe, Al, and other cations are precipitated as the vanadate salts at pH 6, leaving Ca2+(aq) in the solution; (3) the vanadate component is transferred to the liquid phase by dissolving the precipitate in a NaOH(aq) solution of pH 13, leaving Fe, Ti, and Ni ions in the solid phase; and finally, (4) the pH of the solution is adjusted to 2. The vanadium component is solidified as sodium vanadate and V2O5. The maximum yield of vanadium from the slag is evaluated as 80.7%, obtaining for NaV6O15 and V2O5 with a purity of 97 mass %.

The acidic ferric sulfate leaching of primary copper sulfides under recycle solution conditions observed in heap leaching. Part 1. Effect of standard conditions

Understanding the dissolution of copper from chalcopyrite is important as chalcopyrite is the most abundant copper mineral in the earth's crust. The main method for extraction of copper from chalcopyrite is by flotation concentration before being smelted and electro-refined. However, this process is not suitable for the treatment of the vast reserves of low grade chalcopyrite ores, where hydrometallurgical extraction through heap leaching is a better option. While pressure or high temperature leaching with the addition of sodium chloride or HCl have been proposed to extract copper from chalcopyrite concentrates, this process is too expensive to treat low grade copper ores. Currently the research focus to develop a treatment process involves the use of bacteria to oxidise the sulfide minerals and produce sulfuric acid. Given the slow extraction rates of this process it requires decades to extract all the copper from the mineral which would mean the leach solution would therefore be recycled during the process once the copper had been removed. While previous studies have reported the effect of leach temperature, pH (acid concentration) and Eh on copper extraction, these have only considered initial leaching conditions. Studies using recycle leach solution conditions have not been undertaken, and this is the focus of the study reported here. The recycle solution conditions were based on a simulated long term solution composition. This article is part of a series of papers that has investigated the effect on copper and iron extraction from chalcopyrite which has evaluated conditions, major species and additives under recycle leach concentrations. This article examines the effect of the conditions, specifically temperature, pH, Eh and solids density. It was determined that the temperature had the most significant effect on the copper and iron extraction while the pH, Eh or solids density had no appreciable effect on the extraction of either copper or iron under the recycle leach conditions tested. While the effect of temperature on chalcopyrite dissolution is known, the activation energy, the rate of dissolution and the degree of copper extraction is lower under these high solute or recycle concentrations. Similar observations were found when studying pyrite but this study attributed the lowering of these parameters under recycle conditions to the sulfate concentration causing a diffusion layer around the mineral particles which alters or slows the response of pH, Eh or temperature on the dissolution reaction.

Hydration of dicalcium silicate and diffusion through neo-formed calcium-silicate-hydrates at weathered surfaces control the long-term leaching behaviour of basic oxygen furnace (BOF) steelmaking slag

Alkalinity generation and toxic trace metal (such as vanadium) leaching from basic oxygen furnace (BOF) steel slag particles must be properly understood and managed by pre-conditioning if beneficial reuse of slag is to be maximised. Water leaching under aerated conditions was investigated using fresh BOF slag at three different particle sizes (0.5–1.0, 2–5 and 10 × 10 × 20 mm blocks) and a 6-month pre-weathered block. There were several distinct leaching stages observed over time associated with different phases controlling the solution chemistry: (1) free-lime (CaO) dissolution (days 0–2); (2) dicalcium silicate (Ca2SiO4) dissolution (days 2–14) and (3) Ca–Si–H and CaCO3 formation and subsequent dissolution (days 14–73). Experiments with the smallest size fraction resulted in the highest Ca, Si and V concentrations, highlighting the role of surface area in controlling initial leaching. After ~2 weeks, the solution Ca/Si ratio (0.7–0.9) evolved to equal those found within a Ca–Si–H phase that replaced dicalcium silicate and free-lime phases in a 30- to 150-μm altered surface region. V release was a two-stage process; initially, V was released by dicalcium silicate dissolution, but V also isomorphically substituted for Si into the neo-formed Ca–Si–H in the alteration zone. Therefore, on longer timescales, the release of V to solution was primarily controlled by considerably slower Ca–Si–H dissolution rates, which decreased the rate of V release by an order of magnitude. Overall, the results indicate that the BOF slag leaching mechanism evolves from a situation initially dominated by rapid hydration and dissolution of primary dicalcium silicate/free-lime phases, to a slow diffusion limited process controlled by the solubility of secondary Ca–Si–H and CaCO3 phases that replace and cover more reactive primary slag phases at particle surfaces.

Roasted zinc concentrate leaching: Population balance modeling and validation

A Population Balance (PB) model was developed for the sulfuric acid leaching of a roasted zinc concentrate (RZC). Considering that no previous work has validated with experimental data a PB model for this system, leaching experiments were done in order to validate and refine the proposed model. Initially, the chemical and mineralogical composition of the RZC, determined by XRF, XRD, and AAS, indicated the predominance of zinc (65% w/w), mainly as zincite. Next, leaching experiments were carried out using typical conditions of industrial processes. The parameters investigated were the stirring speed, the acid concentration, the reaction time, and the molar ratio, which is the molar ratio between the acid and the zincite present in the RZC loaded to the reactor. It was observed that the acid concentration affected had the major influence on the initial leaching rate, while the molar ratio determined the maximum zinc extraction achieved. It was also found that the model correctly described this behavior, which suggests that the model accounted for the major phenomena occurring during the leaching. Then, using statistical analysis, it was found an excellent agreement between the experimental and calculated data, which verified the validity and accuracy of the proposed model. A potential application of this model would be predicting the effect of changes in operational parameters (e.g., particle size, distribution polydispersity, and acid concentration) on the reactor performance. Thus, the model provides a robust technique for plant design and control, which may lead to better decision-making and costs reduction.

Recovery of gallium from Bayer red mud through acidic-leaching-ion-exchange process under normal atmospheric pressure

The Bayer red mud (BRM), generally containing 0.002wt%–0.008wt% of gallium (Ga), is an overlooked resource of Ga. In this work, an efficient method, called acidic-leaching-ion-exchange process (ALIEP), was developed to extract Ga from BRM. The ALIEP method involved three main steps: the BRM sample was firstly dissolved by mineral acid and the obtained leaching solution was further purified to remove the Fe3+. Consequently, the purified solution, pre-concentrated by re-circulation process, was efficiently treated by ion-exchange process for the Ga recovery. The main influencing factors of the acidic-leaching process were systematically investigated. The optimal Ga leaching conditions were determined as HCl 159g/L, liquid-to-solid ratio of 8mL/g, 55°C, and 5h, attaining Ga leaching rate of 94.77% and the corresponding Ga3+ concentration of 3.91mg/L in leachate. A nearly complete iron removal from the leachate was achieved by employing LSD-396 resin under conditions of 45±2°C, resin dosage of 0.6g/mL and 2h. Subsequently, the recovery efficiency of Ga from re-circulation leaching solution using the ion-exchange technology was evaluated. The results indicated that an adsorption rate of 59.84% and desorption rate of 95.32% for Ga were obtained. The concentrated solution contained 97.54mg/L of Ga, which was enriched 24.95 and 4.75 times compared to the initial leaching solution of 3.91mg/L and re-circulation solution of 20.52mg/L, respectively.

Effect of temperature on copper, iron and lead leaching from e-waste using citrate solutions

E-waste is a potential source of large quantities of metals. The ability of citrate solutions to recover base metals from these materials has been demonstrated. In the present study, the effect of the temperature on base metal leaching capacity by the citrate solutions is determined. The material employed consisted of a mechanically prepared, gravity concentrated e-waste, with a metallic content greater than 90%. The leaching conditions were selected based on previous research performed by the authors (0.5 M sodium citrate, pH 4.5 and 20 g per liter e-waste concentrate). Leaching tests were performed at temperatures between 0° and 70 °C. The initial leaching rates for the three metals increased with temperature. However, these tapered off with time for temperatures above 30 °C, which can be associated to citrate destruction.

Processing of chalcopyrite ore by heap leaching and flotation

This study explored the processing of chalcopyrite ore through heap leaching followed by flotation. Crushed and agglomerated chalcopyrite ore was subjected to bacterially-assisted leaching at ambient temperature in columns that ranged in height from 1m to 5m. >50% extraction was obtained after 16months. Chalcopyrite leaching was affected only by time, not irrigation rate, acid delivery rate, or column height. This indicated that chalcopyrite heap leaching was reaction-limited rather than transport-limited, and therefore relatively impervious to scale. The findings suggest that chalcopyrite could be leached in substantially taller heaps, releasing proportionally greater quantities of copper, without sacrificing recovery. Leaching of the chalcopyrite ore had little effect on its floatability, as indicated by rougher flotation testing. The maximum flotation recoveries, RMAX, were 90% and 88% for the ore and leached residues, respectively. The combined leach/float recoveries were greater than the individual copper recoveries from leaching and flotation alone. This was simply due to the initial leaching step recovering some of the copper that would have been inevitably lost to flotation tailings. Such a leach/float approach may actually benefit from the low reactivity of chalcopyrite, which ensures that leaching would never be so extensive as to affect the later floatability of the mineral.

Release and microbial degradation of dissolved organic matter (DOM) from the macroalgae Ulva prolifera

Release and microbial degradation of dissolved organic matter (DOM) and chromophoric dissolved organic matter (CDOM) from the macroalgae Ulva prolifera were studied in laboratory incubation experiments. The release of DOM and CDOM from Ulva prolifera was a rapid process, and hydrolysis played an important role in the initial leaching of the organic compounds from the algae. Bacterial activity enhanced the release of DOM and CDOM during degradation of the algae and utilization of the released organic compounds. It is calculated that 43±2% of the C and 63±3% of the N from Ulva prolifera's biomass were released during the 20-day incubation, and 65±3% of the released C and 87±4% of the released N were utilized by bacteria. In comparison, only 18±1% of the algae's C and 17±1% of its N were released when bacterial activities were inhibited. The fluorescence characteristics of the CDOM indicate that protein-like DOM was the major organic component released from Ulva prolifera that was highly labile and biodegradable. Bacteria played an important role in regulating the chemical composition and fluorescence characteristics of the DOM. Our study suggests that the release of DOM from Ulva prolifera provides not only major sources of organic C and N, but also important food sources to microbial communities in coastal waters.

Transformation of Selenium-Containing Phases in Copper Anode Slimes During Leaching

The transformation of selenium-containing phases in copper anode slimes during the leaching process was investigated based on the Eh–pH diagram, leaching efficiencies of metals, and characterization of the residues produced during leaching. The leaching efficiency of selenium increases slowly to 17.7% in the first 50 min and then more rapidly to 98.3% in the next 110 min. The Eh–pH diagram indicates that elemental selenium is an intermediate product of the oxidation of selenide to selenite. The x-ray powder diffraction data and scanning electron microscopy–energy-dispersive x-ray spectroscopy data demonstrate that selenium leaching can be divided into three stages. Ag-Cu selenide first transforms into silver selenide and then converts to elemental selenium. Finally, elemental selenium is dissolved as selenite. The intermediate product, elemental selenium, is the main reason for the slow initial leaching rate of selenium.

Application of lime in two-stage purification of leaching solution of spent vanadium catalysts for sulfuric acid production

Two-stage hydrolytic purification of acidic solution of reductive leaching of spent vanadium catalysts for sulfuric acid production from arsenic and iron impurities has been investigated. After oxidation of Fe(II) and As(III) with hydrogen peroxide and neutralization of vanadium (IV) solution with lime to рН2.8 at 25°С, the concentration of iron and arsenic has been reduced from 4.5 to 1.6g·L−1 and from 1.0 to 0.6g·L−1, correspondingly. After neutralizing excessive acidity to рН8.5 at 60°С and oxidation of vanadium, the concentration of iron and arsenic in obtained solutions of sulfates and vanadates of alkali metals does not exceed 0.1mg·L−1. Lime's calcium ions are bound with excessive sulfate ions to form gypsum, which allows to preserve the composition of promoter salts and to return them into production of catalysts after vanadium separation. Washing of the second stage precipitation with initial leaching solutions allows to avoid vanadium losses, guarantees return of impurities to the first stage and their extraction in a convenient form for arsenic burial. The kinetic equation for an oxidation of vanadium (IV) solutions with atmospheric oxygen during their neutralization with lime in presence of ferric compounds has been acquired.

Decomposition of aquatic pioneer vegetation in newly constructed wetlands

Artificial wetlands are constructed around the globe for a variety of services, including wastewater treatment and carbon storage. To become a carbon sink, a newly constructed wetland must have a fully developed vegetation, consisting of species that can produce more organic matter than is being lost through decomposition. However, the effects of environmental conditions on the overall balance between production and decomposition might be complex. In this study, two large-scale field litterbag experiments were performed in a three-year old constructed wetland in the Netherlands, to separate the effects of litter characteristics and environmental conditions on decomposition rates of aquatic pioneer vegetation. Dimension reduction by principal component analysis was used to limit the number of variables for subsequent analyses in linear models. When transplanted to one common environment, litter characteristics alone could explain 52% and 26% of the variation in decomposition after 6 and 12 months, respectively. When both litter characteristics and environmental conditions were tested simultaneously and litter was decomposed in its original environment, 37% and 23% of the variation could be explained after 6 and 12 months, respectively. Both experiments showed two phases of decomposition: the initial leaching phase with an important role for litter characteristics and microbial communities in the model, and the second, slower phase, which is predominantly determined by litter characteristics and environmental conditions such as water quality. Model results could not be extrapolated to a fully developed reference area. Optimization of conditions in order to limit decomposition rates seems difficult and therefore we suggest using management options to influence biomass production and thereby fully exploit the use of newly constructed wetlands for carbon storage.

Leaching behavior of U, Mn, Sr, and Pb from different particle-size fractions of uranium mill tailings.

Pollution by the release of heavy metals from tailings constitutes a potential threat to the environment. To characterize the processes governing the release of Mn, Sr, Pb, and U from the uranium mill tailings, a dynamic leaching test was applied for different size of uranium mill tailings samples. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS) were performed to determine the content of Mn, Sr, Pb, and U in the leachates. The release of mobile Mn, Sr, Pb, and U fraction was slow, being faster in the initial stage and then attained a near steady-state condition. The experimental results demonstrate that the release of Mn, Sr, Pb, and U from uranium mill tailings with different size fractions is controlled by a variety of mechanisms. Surface wash-off is the release mechanism for Mn. The main release mechanism of Sr and Pb is the dissolution in the initial leaching stage. For U, a mixed process of wash-off and diffusion is the controlling mechanism.

Preparation of CO-tolerant anode electrocatalysts for polymer electrolyte membrane fuel cells

The preparation and the thorough characterization of 40 wt% Pt electrocatalysts supported on Ti(1−x)MxO2-C (M = W, Mo; x = 0.3–0.4) composite materials with enhanced stability and efficiency is presented.W-containing composite supported catalyst with different structural characteristics were compared in order to explore the influence of the nature of the W species on the electrocatalytic performance. The assessment of the electrochemical properties of the novel catalysts revealed a correlation between the degree of W incorporation, the hydrogen spillover effect and the stability against initial leaching which influences the activity and CO tolerance of the catalysts.A preparation route for Ti0.7Mo0.3O2-C composite with high extent of Mo incorporation was developed. No significant difference was observed in the activity, stability and CO tolerance of the W- or Mo-containing composite supported Pt catalysts with almost complete incorporation of the oxophilic dopant. Better performance of the Pt/Ti0.7M0.3O2-C (M = W, Mo) electrocatalysts in a single cell test device using hydrogen containing 100 ppm CO compared to the reference Pt/C and PtRu/C (Quintech) catalysts was also demonstrated.

Nitrogen Dynamics of Strawberry Cultivation in Vermicompost-Amended Systems

ABSTRACTThe use of vermicompost as a soil amendment is suggested as a method to reduce nitrogen (N) losses in crop production; however, it is unclear whether and how vermicompost can affect water quality after a significant irrigation or rainfall event. Bare-root strawberry plugs were grown in 1-gallon plastic pots. The treatments consisted of two media: (1) a peat:perlite soil-less mix and (2) a fine sand soil. Each media was amended with three levels of dairy manure vermicompost: 0, 10, and 25% by weight, and a biweekly synthetic fertilizer treatment of 150 mg N-P-K L−1 evaluated in a full factorial randomized block design. Drainage water from each plant was collected each week for 18 weeks and analyzed for NO3− concentration. In the first 2 weeks, high (1000–5000 mg L−1) amounts of NO3− leaching occurred in all vermicompost-amended media relative to non vermicompost-amended media, but this leaching significantly (p < 0.01) decreased over time across all vermicompost treatments. Strawberry growth response to 10% vermicompost was similar to synthetic fertilizer only treatments. Plants grown with vermicompost at 25% with synthetic fertilizer had the highest above-ground vegetative biomass (15.3 g) relative to plants with synthetic fertilizer only (5.3 g). These data suggest vermicompost addition rates of 10 and 25% by weight promote high vegetative biomass in greenhouse strawberry but may facilitate high initial nitrate leaching, which can negatively affect water quality and environmental health.

Release and Microbial Degradation of Dissolved Organic Carbon and Nitrogen from Phragmites australis and Suaeda salsa in the Wetland of the Yellow River Estuary

Release of dissolved organic matter (DOM) and chromophoric dissolved organic matter (CDOM) from two dominant plants Phragmites australis and Suaeda salsa in the Yellow River Estuarine wetlands was studied in laboratory incubation experiments. The release dynamic of dissolved organic carbon (DOC), dissolved nitrogen (DN) and CDOM from the plants was rapid process and hydrolysis played an important role in the initial leaching stage of the organic compounds from the plants. Bacterial activities enhanced the release processes of DOM during degradation of the plants and utilization of the released organic compounds. The fluorescence characteristics of the CDOM indicate that the proteinlike organic substances are the major components released from P. australis and S. salsa in the initial stage and these compounds are labile and highly biodegradable. Our study suggests that leaching of DOM from P. australis and S. salsa provide not only major sources of DOC, DN, and CDOM that affect many biogeochemical processes, but also as important food sources supporting microbial communities in the Yellow River wetlands and adjacent coastal waters.

Effects of Acidithiobacillus ferrooxidans and Fe(III) on pyrite–pyrolusite bioleaching process

The beneficial effects of Acidithiobacillus ferrooxidans and/or Fe(III) on manganese bioleaching from a low-grade manganese ore were confirmed. The results showed that the rate of manganese bioleaching increases with the amount of A. ferrooxidans and/or Fe(III). With the presence of Fe(III) and A. ferrooxidans the average initial leaching rate increased from 0.06 to 0.15 g/(L h). Cyclic voltammetry analysis showed that the presence of A. ferrooxidans and/or Fe(III) generate obvious redox potential polarization in the solution. Fe(III) reduced the potential difference between anode and cathode of pyrite and promoted the positive cathodic polarization of pyrolusite at 0.2 V. In the process of pyrite oxidation A. ferrooxidans accelerated the generation and transfer of electron.

Stabilization of Heavy Metal-Contaminated Sediment with a Chelator and Humic Acid Mixture

A chelator, potassium dipropyl dithiophosphate, and humic acid were combined and used as a stabilizing agent to study the stabilization effect of the mixture on heavy metals in a contaminated sediment. The results indicated that the stabilization efficiencies for Cu, Zn, Pb, and Cd in the sediment were up to 99.98, 90.66, 99.38, and 92.83%, respectively, and the unstable Cu, Zn, Pb, and Cd fractions fell by 57.11, 54.74, 56.41, and 89.14%, respectively, when 5% potassium dipropyl dithiophosphate and 7% humic acid were added. This significantly reduced the bioavailability of the heavy metals. Under leaching caused by simulated acid rain (pH 3 and pH 5), the heavy metals mainly migrated from the solid phase to the liquid phase during the initial leaching period, and the Pb, Cu, Zn, and Cd leaching rates in the sediment after stabilization fell by 55–99%. Cu showed the greatest reduction. When the results for the sediment after stabilization were compared with the sediment before stabilization, the wheat stem height had increased by 53.62%, the dry weights of the leaves and roots increased by 86.25 and 34.85%, respectively, and Cu, Zn, Pb, and Cd enrichment in the wheat roots and leaves fell by 40–88 and 73–95%, respectively.