Processing of polymetallic sea nodules: An overview

Polymetallic sea nodules are the potential sources of copper, nickel, cobalt and manganese. As the land based resources of these metals are depleting very fast, a considerable R&D effort have been made all over the world to extract the metals from the sea nodules during the past four decades. The paper summarises the processes developed by various R&D organisations and metallurgical consortia for the extraction of metal values from the sea nodules. Since the copper, nickel and cobalt in the sea nodules are in oxide Forms and they associate in the lattices of iron and manganese minerals, for extraction of these metals the lattices are broken either by hydrometallurgical reduction or by reductive pyre-treatment. Based on this criteria, processing methods have been broadly divided into two categories : (i) pyrometallurgical treatment followed by hydrometallurgical processing and (ii) purely hydrometallurgical processing. Processes developed under these two categories have been discussed highlighting their merits and demerits. Pilot plant studies carried out by various metallurgical consortia like Knnecott Copper Corporation, Deep Sea Ventures, Metallurgie Hoboken - Overpelt, International Nickel Company are also given. The R&D efforts made in India in the processing of sea nodules during last one decade and the future programme are also discussed

Processing of dust materials from Indian copper plants

In the pyrometallurgical processing of copper are, there is considerable amount of copper losses in the form of dust from the roaster, smelter and converter. Most of this dust is simply charged back into the smelting cir¬cuit, thereby reducing the capacity offresh charge processing. In the present paper separate processing of copper dust sample by sulphuric acid leaching method has been examined with the idea that the resulting leached cop¬per sulphate solution can be used as electrolyte in the copper electro¬refining section of the plant. The copper dust sample from Khetri Copper Complex, Rajsthan contained about 22% copper. The XRD analysis of the sample revealed that copper was mainly present in the forms of ox¬ides, sulphates and sulphides. Simple water leaching of the dust sample dissolved copper to the tune of 30%. This implied that about 30% of cop¬per was present in the sulphate form and rest of the copper was in the oxide and sulphide forms for which acid leaching process might be suit¬able. Sulphuric acid leaching at various concentration and at varied solid : liquid ratio, time and temperature were carried out at atmospheric pressure. The maximum recovery of copper obtained in these experiments was found to be about 52%. Since the sulphuric acid leaching at atmospheric presssure did not yield good results, the dust sample was leached at higher pressure in an autoclave on 200 g scale and the recovery of copper improved to 80%

Reduction of Emission from Aluminium Industries and Cleaner Technology

Aluminium metal is produced by electrolytic reduction of alumina in cells lined with carbon blocks. During the process of smelting different gaseous emissions like PFC (per flurocarbon).HF PAH (poly aromatic hydrocarbon), CO2, SO„ particulate matters etc. occur in to the atmosphere. The concentration of emission from a cell depends upon the type of cell, bath chemistry, scrubbing system and gas cleaning equipment used. These emissions cause severe environmental damages such as global warming and disease like fluorosis, cancer, asthma, emphysema, bronchitis etc. Through the development of newer technologies like, intro-duction of prebake technology, use of non-consumable (inert) anode, use of computer controlled and point feeding of alumina to the cell to control the frequency and duration of anode effects, use of low carbon pitch to replace tar, use of pollution monitoring and control equipment etc., there is a significant reduction in the emission levels. This paper deals with the factors infl-uencing the generation of these emissions and its reduction through the development of various cleaner technologies. Use of pollution control equipment and other remedial mea-sures to minimise the environmental pollution are also discussed

AN INTELLIGENT HYBRID SCHEDULING ALGORITHM FOR COMPUTER AIDED PROCESS CONTROL OF MANUFACTURING SYSTEM

In recent times, maintaining stable and efficient operation, industrial automation and control systems that quickly respond to change is become a tedious task. Although the purpose of process scheduling is different according to the classes of process, the conventional methods have scheduled every process equivalently because they do not know the classes of process. To overcome this limitation, intelligent process scheduling method has to be developed to help the complexity associated with industries. In this paper, an intelligent algorithm is developed to do process scheduling of manufacturing system. Here, the proposed method utilizes a recent soft computing algorithm called, cuckoo search and traditional algorithm, called genetic algorithm.  These two algorithms are effectively combined to do intelligent process scheduling. Initially, solutions are encoded effectively by considering the sequential order, set up selection and machine selection. Solution is nothing but the order of process to be carried out sequentially by considering machine availability, set up condition and predefined order of machine ordering. Then, the fitness of the solution are found out using the fitness that considers machine cost of doing task, set up cost and machine change cost. After designing the solution coding and fitness function, the intelligent scheduling will be done with the help of HCGA algorithm which is developed by combining cuckoo search and genetic algorithm. The experimental results showed that, the proposed approach gives fitness rate of 0.82 and which helps to achieve the scheduling in limited time, listed as 22000 sec on an average.

Hepatoprotective activity of ethanol extract of Pavetta Indica Linn leaves

Background: Traditionally, the bark of Pavetta Indica Linn., in decoction or pulverized, is administered, especially to children, to correct visceral obstructions. The decocted leaves are used externally to alleviate the pains caused by hemorrhoids. The root, pulverized and mixed with the ginger and rice-water, is given in dropsy. A local fomentation with the leaves is useful in relieving the pain of piles. Paracetamol (PCM) toxicity generates free radicals and raised serum enzyme levels-SGPT, SGOT, Alkaline Phosphatase and S. Albumin. It causes necrosis, congested vessels, multifocal area of fatty changes nuclear disintegration, sinusoidal dilation, kuffer cell hyperplasia. The reverse is considered as the index of hepatoprotective activity. The present study is being taken up to screen hepatoprotective action of P. Indica Linn.Methods: The acute liver damage in albino rats was induced by per oral administration of a single dose of 2000mg/kg b.w. PCM suspension in 0.5% Carboxy methyl cellulose (CMC) and chronic liver damage by giving the same dose of PCM on the 7th day. The hepatoprotective activity was monitored biochemically by estimating S. transaminase, S. bilirubin and S. Protein on the 8th day of experiment.Results: Ethanol extract of P. Indica inhibited PCM induced liver toxicity in albino rats at 100mg/kg and 200mg/kg b.w as assessed by the biochemical values.Conclusions: Ethanol extract of “P. Indica” exhibited significant hepatoprotective activity

Role of impurities in solvent extraction-electrowinning of copper and nickel for the processing of sea nodules

During the leaching of roasted nodules from Indian Ocean the soluble amine species of iron, manganese and zinc along with valuable metals such as Cu, Ni and Co enter the ammoniacal solution. Even after the purification step, the metal impurities in small amounts remained in the leach solution. In metal separation using LIX 64N, iron and manganese found their way in the nickel and copper electrolytes. Depending on the feed pH of the nickel spent electrolyte, the selective nickel stripping could be achieved with minimum contamination of copper. A flow sheet based on co-extraction-selective stripping has been developed to process the ammoniacal leach liquor of Indian Ocean nodules. While running the continuous SX-EW circuit, the build-up of metallics (Fe and Mn) and organic impurities in the nickel electrolyte was observed which affected the deposition. The cut-off impurity level in electrolyte for nickel winning was determined as : 0.175 Kg/m(3) Mn, 0.010 Kg/m(3) Fe and 20 ppm organic reagent. A purification scheme for nickel bleed stream was developed to recycle the electrolyte back to SE-EW circuit. Copper being a more noble metal than nickel can usually tolerate higher level of impurities. Organic levels of less than 100 ppm in the copper electrolyte produced good sheet deposit. The results showed the possibility of producing electrolytic grade copper and nickel metals of 99.94% and 99.8% purity

Processing of Tungsten Alloy Scrap for the Recovery of Tungsten Metal

Penetrators usedfordefence purposes are prepared by po wder metallurgical technique. The material contains 90% tungsten along with other minor constituents such as iron, nickel, cobalt, chromium, aluminium etc. During the manufacturing process, three forms of scraps are generated whichare, powder, turnings and defective solid. Since the major constituents of the scrap is the costly tungsten metal, attempts were made to recover the metal by four different methods which are described in this paper. Electro-leaching of turnings in a diaphragm cell using chloride electrolyte bath was tried to remove minor elements. The purity of tungsten achieved in thisprocess was 99.9%. In the soda roasting - leaching process of powderliurning scraps, sodium tungstate of 99.85% purity was obtained with 90% yield. Attempt was also made to remove the impurities by acid leaching. 99.8% pure tungsten with 99% yield was achieved by acid leaching. Fine gravity separation and high intensity magnetic separation techniques were also adopted to enhance the tungsten value from the powder scrap, which produced the concentrate containing 96.2% tungsten

Control of western corn rootworm via RNAi traits in maize: Lethal and sublethal effects of Sec23 dsRNA

Background: RNA interference (RNAi) triggered by maize plants expressing RNA hairpins against specific western corn rootworm ( WCR) transcripts have proven to be effective at controlling this pest. To provide robust crop protection, mRNA transcripts targeted by double-stranded RNA must be sensitive to knockdown and encode essential proteins. Results: Using WCR adult feeding assays, we identified Sec23 as a highly lethal RNAi target. Sec23 encodes a coatomer protein, a component of the coat protein (COPII) complex that mediates ER-Golgi transport. The lethality detected in WCR adults was also observed in early instar larvae, the life stage causing most of the crop damage, suggesting that WCR adults can serve as an alternative to larvae for dsRNA screening. Surprisingly, over 85% transcript inhibition resulted in less than 40% protein knockdown, suggesting that complete protein knockdown is not necessary for Sec23 RNAi-mediated mortality. The efficacy of Sec23 dsRNA for rootworm control was confirmed in planta; T0maize events carrying rootwormSec23 hairpin transgenes showed high levels of root protection in greenhouse assays. A reduction in larval survival and weight were observed in the offspring of WCR females exposed to Sec23 dsRNA LC25in diet bioassays. Conclusion: We describe Sec23 as RNAi target for in planta rootworm control. High mortality in exposed adult and larvae and moderate sublethal effects in the offspring of females exposed to Sec23 dsRNA LC25, suggest the potential for field application of this RNAi trait and the need to factor in responses to sublethal exposure into insect resistance management programs. Includes supplemental materials

Myocardial fibrosis in asymptomatic and symptomatic chronic severe primary mitral regurgitation and relationship to tissue characterisation and left ventricular function on cardiovascular magnetic resonance

Background: Myocardial fbrosis occurs in end-stage heart failure secondary to mitral regurgitation (MR), but it is not known whether this is present before onset of symptoms or myocardial dysfunction. This study aimed to characterise myocardial fbrosis in chronic severe primary MR on histology, compare this to tissue characterisation on cardiovascular magnetic resonance (CMR) imaging, and investigate associations with symptoms, left ventricular (LV) function, and exercise capacity. Methods: Patients with class I or IIa indications for surgery underwent CMR and cardiopulmonary exercise testing. LV biopsies were taken at surgery and the extent of fbrosis was quantifed on histology using collagen volume fraction (CVFmean) compared to autopsy controls without cardiac pathology. Results: 120 consecutive patients (64±13 years; 71% male) were recruited; 105 patients underwent MV repair while 15 chose conservative management. LV biopsies were obtained in 86 patients (234 biopsy samples in total). MR patients had more fbrosis compared to 8 autopsy controls (median: 14.6% [interquartile range 7.4–20.3] vs. 3.3% [2.6–6.1], P<0.001); this diference persisted in the asymptomatic patients (CVFmean 13.6% [6.3–18.8], P<0.001), but severity of fbrosis was not signifcantly higher in NYHA II-III symptomatic MR (CVFmean 15.7% [9.9–23.1] (P=0.083). Fibrosis was patchy across biopsy sites (intraclass correlation 0.23, 95% CI 0.08–0.39, P=0.001). No signifcant relationships were identifed between CVFmean and CMR tissue characterisation [native T1, extracellular volume (ECV) or late gadolinium enhancement] or measures of LV function [LV ejection fraction (LVEF), global longitudinal strain (GLS)]. Although the range of ECV was small (27.3±3.2%), ECV correlated with multiple measures of LV function (LVEF: Rho=−0.22, P=0.029, GLS: Rho=0.29, P=0.003), as well as NTproBNP (Rho=0.54, P<0.001) and exercise capacity (%PredVO2max: R=−0.22, P=0.030). Conclusions: Patients with chronic primary MR have increased fbrosis before the onset of symptoms. Due to the patchy nature of fbrosis, CMR derived ECV may be a better marker of global myocardial status. Clinical trial registration Mitral FINDER study; Clinical Trials NCT02355418, Registered 4 February 2015, https://clinicaltr ials.gov/ct2/show/NCT0235541