Physical method of upgradation for low grade wolframite pre-concentrate from Degana, Rajasthan

Tungsten is a strategic metal and mostly used in defence. It is also used in cutting tools, industrial, electrical, textile and leather sectors. India's tungsten reserves are very limited and the only workable deposit is restricted to Degana in Rajasthan. Tungsten deposit occurs in association with metamorphic rocks and granite igneous rock throughout the world. At Degana, two types of deposit are being worked at, one being quartz load wherein wolframite is mineralised in quartz vein and the other is finely disseminated tungsten mineralisation in the granite body. The sample under investigation belonged to off-grade tungsten pre-concentrate - I (PC - 1) produced at Degana Plant site, assaying 14.50% WOe 20.20% SiO, and 4.13% S. The objective of this study was to find the upgradation conforming to DMRL specification i.e. final wolframite concentrate with >65.0% WO,, and S and SiO, < 1.0% each. Detailed studies indicated that grinding the feed to 200 mesh followed by sulphide flotation at 4.5 and 8.0 pH and repeated vanning of non-sulphide could produce a wanner concen¬trate assaying 64.8% WO,. 1.0% SiO, and 3.0% S with a distribution of 48.8% WO3 in it. Thorough desliming followed by sulphide flotation and then treating on vanner times could produce a concentrate analysing 68.47% WO j, 0.5% SiO3 and 0.48% S which conforms to the DMRL sped¬fications

Enumerative geometry of Calabi-Yau 4-folds

Gromov-Witten theory is used to define an enumerative geometry of curves in Calabi-Yau 4-folds. The main technique is to find exact solutions to moving multiple cover integrals. The resulting invariants are analogous to the BPS counts of Gopakumar and Vafa for Calabi-Yau 3-folds. We conjecture the 4-fold invariants to be integers and expect a sheaf theoretic explanation. Several local Calabi-Yau 4-folds are solved exactly. Compact cases, including the sextic Calabi-Yau in CP5, are also studied. A complete solution of the Gromov-Witten theory of the sextic is conjecturally obtained by the holomorphic anomaly equation.Comment: 44 page

Studies on Beach Placers of Kerala Coast

In the present paper, studies carried out on beach placer samples of Kerala coast in general and contribut-ions of NML and its current activities in particular on beach sands of Kerala have been discussed. While earlier beneficiation study at NML was on purification of zircon, present study, under network project, consist of charac-terization of samples from different areas to identify prospective area that will be taken up for development of process technology. Characterisation studies involve size and chemical analyses, sink and float studies, optical microscopy and scanning electron microscopy. Samples from four different areas (Valarpattanam Azhikod (VA), Chava-kkad Ponnani (CP), Neendakara Kayamkulam (NK) and Warkala coast) were studied. It has been found that while heavy mineral concentration at NK and Warkala coast is quite high, the same at CP is rather low in comparison and at VA it's not significant

Floatation Studies on Processing of a Low Grade Uranium Ore

This paper deals with the results of flotation studies carried towards pre-concentration of a low-grade uranium ore sample from Domiasiat, Meghalaya. A comb-ination of potassium amyl xanthate, cupferron and light diesel oil was used as collector for flotation of uran- ium bearing minerals in the sample. The effects of vari-ous process parameters were studied. Under the optimum conditions the flotation concentrate weighed about 35 % with over 90 % recovery. Flotation with classified / deslimed feed also resulted in similar metallurgical results. Use of diethyl hexyl phosphoric acid, alamine 336 & tri-butyl phosphate in combination with potassium amyl xanthate and light diesel oil, as the alternate reagent scheme, also gave reasonably high uranium recovery

Beneficiation studies on Bolani iron ore

The iron ore washing plants generate slime on an average of 10 - 20% by weight of the ore and is wasted. Apart from loss of resource, these slimes pose problem of disposal and consequent damage to environment. To reduce problems of slime, it should be treated, as a part of beneficiation, to minimise waste generation. Out of five number of different varieties of Bolani iron ore bulk samples, two bulk composite samples were prepared in the proportions as decided by the sponsor. The first sample was found to be of very good quality assaying 66.69% Fe, 1.27% SiO, and 1.8% Al,O and only crushing and sizing (dry) were done for physical characterisation. The second sample (assaying 63.68% Fe, 2.05% SiO, and 2.6% AI,O,) was beneficiated to produce washed lump weighing 49.9% and with assay of 65.0% Fe. 1.8% SiO, and 2.1% Al,Or Combined fines weighed 42.7% assaying 63.95% Fe, 1.81% Si02 and 2.54% A1,03 leaving slime reject 7.4% by weight and assaying 51.27 % Fe, 5.6 % SiO, and 8.82% Al,O3 which not only reduced waste generation but improved recovery also

Reduction of Environment Pollution in Processing of Barite

One of the largest indigenous manufacturing plants of barium chemicals is located at Cuddapah in Andhra Pradesh. During production of barium carbonate, two types of rejects (flue ash and sludge) have been generated and accumulate for last few decades at the Cuddapah plant. Earlier, briquetting of charge was suggested to restrict physical losses of material as flue ash. Afterwards, to generate product having > 90% barium sulphate which could be reused, studies have been carried out with the rejects currently produced. Detailed investigations suggested seperate treatment of sludge because the flue ash sample was found to be suitable as feed to the reduction circuit. Both gravity and flotation processes were found to generate product meeting specification. It was also found that more than 55% of the combined rejects currently generated at Cuddapah plant could be used again for the production of barium carbonate. In the process, recovey of barite value could be more than 64

Minerological aspects of lead sintering

A brief overview on lead sinter microstructure is presented. Characteristic micro-structural features of a good and bad sinter are highlighted and these are used in a case study involving use of a low grade and complex concentrate of lead (-40% Pb) in the sintering operation. The plant sinter produced exhibited low strength and its nticrostructural examination revealed non-uniform distribution of porosity along with unsintered galena and low melting lead silicate phase. Part replacement of limestone by lime helped in producing sinter with good physical properties and desirable microstructure. The sinter with modified feed chemistry had more uniform distribution of porosity and presence of primarily a Pb-Fe silicate phase characterised by a (Pb+Fe):Si mole ratio of 3:1. Ca-Pb-Zn-Fe-Al-silicate phase identified as hardysonite and a spine! phase of the type (Fe,Zn)O.(Fe,Al),OJ. Lead nietal/oxide/sulphide occurred in the sinter only rarely. The likely implications of lime addition to the sinter charge mix are discussed Key Words: Lead. Complex and low grade concentrate. Sintering. Process Mineralog

Designing Flotation Process for Lead-Zinc ore from Nepal

The paper deals with the development of a process based on froth flotation for the concentration of a lead-zinc ore from Ganesh-Himal region of Nepal. A detailed chara-cterisation and flotation studies were carried out under the varying process conditions. The ore was predomionantly made up of sphalerite and pyrite in association with sub-ordinate amount of galena, minor amount of pyrrhotite and chalcopyrite with dolomite as the major gangue. Under the optimum process conditions the rougher lead and zinc recovery were 96.3% and 90.8% respectively. Regrinding followed by three stage cleaning of the lead rougher conc-entrate resulted in cleaner concentrate assaying 79.11 % Pb with 83.4% recovery. Similarly two stage cleaning of the zinc rougher concentrate produced cleaner concentrate analysing 60.08% Zn with 80.4% recovery. Based on the studies undertaken a process flow-sheet for the conc-entration of the ore to individual lead and zinc concen-trates has been recommended

Curve counting via stable pairs in the derived category

For a nonsingular projective 3-fold $X$, we define integer invariants virtually enumerating pairs $(C,D)$ where $C\subset X$ is an embedded curve and $D\subset C$ is a divisor. A virtual class is constructed on the associated moduli space by viewing a pair as an object in the derived category of $X$. The resulting invariants are conjecturally equivalent, after universal transformations, to both the Gromov-Witten and DT theories of $X$. For Calabi-Yau 3-folds, the latter equivalence should be viewed as a wall-crossing formula in the derived category. Several calculations of the new invariants are carried out. In the Fano case, the local contributions of nonsingular embedded curves are found. In the local toric Calabi-Yau case, a completely new form of the topological vertex is described. The virtual enumeration of pairs is closely related to the geometry underlying the BPS state counts of Gopakumar and Vafa. We prove that our integrality predictions for Gromov-Witten invariants agree with the BPS integrality. Conversely, the BPS geometry imposes strong conditions on the enumeration of pairs.Comment: Corrected typos and duality error in Proposition 4.6. 47 page

Addressing the STEM Gender Gap by Designing and Implementing an Educational Outreach Chemistry Camp for Middle School Girls

There continues to be a persistent, widespread gender gap in multiple STEM disciplines at all educational and professional levels: from the self-reported interest of preschool aged students in scientific exploration to the percentages of tenured faculty in these disciplines, more men than women express an interest in science, a confidence in their scientific abilities, and ultimately decide to pursue scientific careers. Reported herein is an intensive outreach effort focused on addressing this gender gap: a full-time, week-long chemistry camp that was designed and implemented for middle school girls in the state of Rhode Island. The camp schedule included multiple hands-on experiments, field trips, and significant interactions with female scientists, all of which were designed to increase the participants’ interest in and enthusiasm for science. The success of the program in changing the participants’ attitudes toward science was measured through administration of a precamp and postcamp survey, and the survey results demonstrated a strong success in changing the participants’ attitudes toward the widespread applicability of science, their perceived level of support for scientific study, and their interest in pursuing STEM-related careers