Comparative Study of Metal Extraction in Different Acid Concentration of Brass Effluent

Metal values including Copper (Cu), Lead (Pb) and Zinc (Zn) have been effectively recovered from brass melting slag through hydrometallurgical treatments employing acid leaching methods utilizing hydrochloric acid (HCl), nitric acid (HNO 3 ), and sulfuric acid (H 2 SO 4 ). The optimization of recovery efficiency was investigated by varying the concentrations of these acid solutions. Acidic leachants proved highly effective, particularly under elevated temperatures, with percent extraction increasing in the order of nitric, hydrochloric, and sulfuric acid. The proposed method achieved a remarkable recovery efficiency exceeding 96%. Furthermore, the recovered Copper and Zinc products meet standard specifications.


Recovery
The Brass Industry in Jamnagar boasts a diverse product range, encompassing various essential items such as auto parts, Electric and Electronics Components, Hardware Parts, surgical instruments etc. [1][2][3][4].In essence, the industry manufactures a wide spectrum of brass parts, ranging from small pins to intricate components, catering to diverse industrial needs.Hence, Jamnagar remains the epicentre of brass parts manufacturing, other regions like Punjab, Uttar Pradesh, and Haryana predominantly focus on the production of showpieces and statues from brass, albeit on a smaller scale in terms of both numbers and overall production volume [5][6][7][8].Industrial dust particles generated by brass foundries have high levels of zinc, copper, iron, and manganese.When these particles settle in and around industrial areas, they can become potential sources of environmental contamination, offering both direct and indirect threats to animal and plant health.Furthermore, these particles can be spread by rain and wind, damaging water sources and soil.As a result, studying these dust particles is critical for recognizing the importance of good dust management, which includes proper trash collection and disposal techniques.These foundries serve as scrap recycling facilities, helping to recycle materials by reintroducing them into production.Recycling is the reuse of trash in production processes with the goal of preserving natural resources and energy.

Materials:
The scrap material used in this study was obtained from Shankar Tekri, Jamnagar, Gujarat.The sample weighing 100-kg contained particles was sieved for particle sizing.The chemicals used in this work were of pure grade.Nitric, hydrochloric and sulphuric acids were used for leaching experiments.Distilled water was used for chemical analysis.Tap water of the city network was used for other purposes.

Methods:
Total sample (Cu, Pb and Zn) should be weighed properly and the part of sample (4.5 g) was taken for the analysis.The sample was dissolved in 5 N to 0.5 N in HNO3, HCl and H2SO4 respectively.The solutions were further evaporated until the evaluation of brown gas was disappears and diluted up to 30 mL with hot water and filtered (Table 1).
Extraction and recovery of copper and lead: The recovered filtrate was taken in a 250 mL beaker and the volume was made up.Electrodes were dipped the filtrate 5 ampere current was passes having 2.5 V with the help of a magnetic stirrer.The electrolysis was carried out for 20 minutes.Followed by 0.5 g of urea was added as a binding agent.After that that the electrodes were removed from the solution and thoroughly washed with water and dried it in a hot air oven for 15 minutes.Completely dried electrodes was weighed to find out the total deposition of metal on the electrode.

𝑪𝒖% = 𝑪𝒖 𝒅𝒆𝒑𝒐𝒔𝒊𝒕𝒆𝒅 𝑻𝒐𝒕𝒂𝒍 𝒘𝒆𝒊𝒈𝒉𝒕 𝒐𝒇 𝒔𝒂𝒎𝒑𝒍𝒆 𝑿 𝟏𝟎𝟎
Where copper deposit should be calculated as the difference of the total weight of electrode and weight of electrode before process start.

𝑷𝒃% = 𝑷𝒃 𝒅𝒆𝒑𝒐𝒔𝒊𝒕𝒆𝒅 𝑿 𝟎. 𝟖𝟔𝟔 𝑻𝒐𝒕𝒂𝒍 𝒘𝒆𝒊𝒈𝒉𝒕 𝒐𝒇 𝒔𝒂𝒎𝒑𝒍𝒆 𝑿 𝟏𝟎𝟎
Where lead deposit should be calculated as the difference of the total weight of electrode and weight of electrode before process start.Procedure: Sample Preparation: Tartaric acid solution (25 ml) was added to the sample once Cu and Pb had been completely removed from it.This was followed by neutralization with concentrated ammonium hydroxide using methyl red as an indicator.After adding a 25 ml combination of formic acid, the solution was heated to between 70 and 80°C.After that, the solution was exposed to hydrogen sulphide gas for 30 minutes.
After letting the zinc sulphide precipitate congeal, it was filtered and cleaned using a warm formic acid wash solution.Hot, diluted sulfuric acid was used to dissolve the precipitate of zinc sulphide, which was then collected in a 250 ml volumetric flask.Next, the solution was thinned to the appropriate level.Using methyl red indicator, a sufficient aliquot of the solution was collected and neutralized with sodium hydroxide solution.EBT indicator (5 drops) and buffer solution (30 ml) were added.The EDTA solution was titrated gradually until a bluish-green endpoint was noticed.
This method provides a comprehensive protocol for the determination of zinc content in a given sample using the EDTA method, ensuring accuracy and reproducibility of results.
Preparation of buffer solution for volumetric analysis: 54 g of ammonium chloride was dissolved in 300 mL of water, followed by 350 mL of ammonium hydroxide was added and diluted to 1 L. the pH of the solution was maintained at 10.

Volumetric Analysis:
Previously  The extraction data of HNO3, HCl and H2SO4 shown in Table -1

Fig. 1 .
Fig. 1.Apparatus used for extraction and recovery of metals.Extraction and recovery of Zinc: Reagents: Concentrated NH4OH (20%), Tartaric Acid (30% w/v), Diluted HNO3 (1:1, v/v), Formic Acid Mix (20 ml FA, 25 g (NH4)2SO4, 3 ml NH4OH, diluted to 100 ml), Methyl Red Indicator (0.1% w/v), H2S gas, Diluted H2SO4 (1:1, w/v), NaOH solution (200 g/l collected ZnS precipitate was dissolved in hot H2SO4 (dil.) in a 250 mL volumetric flask and the volume was made up.The resulting solution was neutralized with NaOH solution and the neutralization point was identified using an indicator (methyl red).30 mL of buffer solution was added to the neutralized solution along with 5 drops of EBT indicator.The resulting solution was titrated against EDTA until the bluish green end point was reached. in ml of EDTA solution required for titration of the solution; B = zinc equivalent in gram% per millimetre of EDTA solution; C = weight in g of sample represented by the aliquot.

Fig. 3 &
Fig. 3 & 4 illustrates the impact of various acids on metal extraction.In Fig. 3, it is evident that the highest extraction of copper is achieved using 0.5 N HCl.Similarly, Fig. 4 indicates that 5 N to 2 N HCl solution is optimal for extracting zinc.These findings underscore the significance of selecting appropriate acid concentrations to maximize metal extraction efficiency.

Table 1 .
Wet Analysis Results