Q7
(a) Give an account of external changes in flora due to the presence of anomalous concentration of base metal in a terrain. (20 marks) (b) Explain the principle for flotation as a benefication technique. Name various parameters that regulate the flotation process. Explain frothing method giving appropriate examples. (15 marks) (c) What do you understand by the term 'industrial minerals'? Give examples of any five industrial minerals, their sources, compositions and uses in the industry. (15 marks)
हिंदी में प्रश्न पढ़ें
(a) एक भूभाग में मूल धातुओं के असामान्य सांद्रण की मौजूदगी के कारण वनस्पति में हुए बाहरी परिवर्तनों का एक विवरण दीजिए। (20 अंक) (b) प्लवन (फ्लोटेशन) के सिद्धांत को एक सज्जीकरण (बेनिफिकेशन) तकनीक के रूप में समझाइए। प्लवन प्रक्रिया को नियंत्रित करने वाले विभिन्न प्राचलों के नाम बताइए। यथोचित उदाहरण देते हुए झाग-कारक (फ्रोथिंग) विधि को समझाइए। (15 अंक) (c) 'औद्योगिक खनिज' शब्द से आपका क्या तात्पर्य है? किन्हीं पाँच औद्योगिक खनिजों के उदाहरण, उनके स्रोत, संयोजन और उद्योग में उपयोगों को बताइए। (15 अंक)
Directive word: Explain
This question asks you to explain. The directive word signals the depth of analysis expected, the structure of your answer, and the weight of evidence you must bring.
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How this answer will be evaluated
Approach
The directive 'explain' demands clear exposition of principles with causal reasoning. Allocate approximately 40% of effort to part (a) given its 20 marks, covering geobotanical indicators, morphological changes, and indicator plants; 30% each to parts (b) and (c). Structure: brief introduction defining geobotany and industrial minerals; body with three clearly demarcated sections addressing each sub-part with diagrams for flotation; conclusion emphasizing exploration-applied mineralogy linkage.
Key points expected
- Part (a): External morphological changes in flora—chlorosis, stunted growth, altered flowering patterns, leaf necrosis; specific copper-tolerant plants like Becium homblei (copper flower) in Zambian/Zairean copper belts and Indian analogues; root system modifications; geobotanical zonation concepts
- Part (a): Mechanism of metal toxicity—enzyme inhibition, nutrient imbalance, membrane damage; visual symptoms as exploration guides; limitations and complementary geochemical methods
- Part (b): Flotation principle—selective hydrophobicity/hydrophilicity based on differential wetting of mineral surfaces; role of collectors, frothers, modifiers, and pH regulators
- Part (b): Key parameters—particle size, pulp density, pH, aeration rate, temperature, reagent dosage, froth depth; frothing method types (mechanical, pneumatic, vacuum) with examples: sulfide flotation (Cu, Pb, Zn) using xanthates; oxide flotation using fatty acids
- Part (c): Definition of industrial minerals—non-metallic, non-fuel minerals valued for physical/chemical properties; distinction from metallic ores and gemstones
- Part (c): Five examples with Indian sources—(1) Talc/steatite (Rajasthan, Andhra Pradesh): Mg3Si4O10(OH)2, ceramics and paper; (2) Limestone (Madhya Pradesh, Rajasthan): CaCO3, cement and steel; (3) Mica (Jharkhand, Bihar): KAl2(AlSi3O10)(OH)2, electrical and electronics; (4) Gypsum (Rajasthan, Tamil Nadu): CaSO4·2H2O, cement and fertilizer; (5) Bentonite (Gujarat, Rajasthan): montmorillonite, drilling mud and foundry
Evaluation rubric
| Dimension | Weight | Max marks | Excellent | Average | Poor |
|---|---|---|---|---|---|
| Concept correctness | 22% | 11 | Demonstrates precise understanding of geobotanical stress responses, flotation surface chemistry (contact angle, zeta potential), and industrial mineral classification; correctly distinguishes between metallic ore minerals and industrial minerals; accurate chemical formulas and genetic processes | Basic grasp of concepts with minor errors in flotation chemistry or incomplete geobotanical mechanisms; some confusion between ore and industrial mineral categories; minor formula errors | Fundamental misconceptions about flotation mechanism, conflates geobotany with biogeochemistry without distinction, or misclassifies minerals; significant chemical/formula errors |
| Diagram / cross-section | 18% | 9 | Clear labeled diagram of flotation cell showing pulp zone, froth zone, impeller mechanism, and air bubble-mineral attachment; schematic of geobotanical zonation around ore body; process flow diagram for froth flotation circuit | Simple sketch of flotation cell without proper labeling or missing key components; generic plant diagram without specific geobotanical application; adequate but not precise | No diagrams where essential; poorly drawn or unlabeled sketches; diagrams that misrepresent the flotation process or show irrelevant illustrations |
| Field evidence | 18% | 9 | Cites specific field examples: copper indicator plants in Khetri belt (Rajasthan), Malanjkhand (Madhya Pradesh); documented cases of vegetation stress over sulfide deposits; actual flotation plant operations (HCL, HZL); specific mining districts for each industrial mineral | General mention of Indian localities without specificity; some field examples but lacking precise mine or deposit names; second-hand reporting without evidentiary weight | No field evidence or purely hypothetical examples; incorrect attribution of deposits to wrong states; confusion between domestic and foreign examples without clarity |
| Quantitative reasoning | 18% | 9 | Includes relevant numerical parameters: typical flotation particle size ranges (10-200 μm), pH ranges for selective flotation (Cu: 8-11, Pb: 7-9, Zn: 10-12), reagent concentrations (g/tonne), grade-recovery relationships; metal concentration thresholds for phytotoxicity | Some quantitative data but incomplete or approximate; mentions pH or size ranges without specificity; lacks numerical depth for industrial mineral specifications | Entirely qualitative treatment where quantitative aspects are expected; incorrect or unrealistic numerical values; no appreciation of process optimization parameters |
| Indian / economic relevance | 24% | 12 | Strong integration of Indian exploration context: GSI geobotanical surveys, Hindustan Zinc's Rampura Agucha, HCL's Khetri; Make in India relevance of self-reliance in critical industrial minerals; import substitution for high-grade talc, specialty clays; environmental regulations governing tailings from flotation plants | Some Indian examples but superficial treatment; mentions domestic deposits without economic significance; limited policy or strategic context | Foreign-centric answer ignoring Indian mineral industry; no appreciation of economic importance or strategic concerns; outdated or irrelevant economic context |
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