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  <xsd:element id="zinc_ContingentconsiderationReductionofestimatedliability" name="ContingentconsiderationReductionofestimatedliability" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="zinc_ContractualCouponInterestPercentage" name="ContractualCouponInterestPercentage" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_ConvertibleDebtFairValueAtIssuance" name="ConvertibleDebtFairValueAtIssuance" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="zinc_ConvertibleNotesMember" name="ConvertibleNotesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="zinc_ConvertibleSeniorNotesMember" name="ConvertibleSeniorNotesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_CopperFixedToVariableContractsOutstanding" name="CopperFixedToVariableContractsOutstanding" nillable="true" substitutionGroup="xbrli:item" type="us-types:perUnitItemType" xbrli:periodType="instant" />
  <xsd:element id="zinc_CostOfDerivativesPurchased" name="CostOfDerivativesPurchased" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="zinc_CostOfSalesExcludingDepreciationAndAmortization" name="CostOfSalesExcludingDepreciationAndAmortization" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="zinc_CostOfSalesOfNickelBasedMaterialAndOtherServicesExcludingDepreciationAndAmortization" name="CostOfSalesOfNickelBasedMaterialAndOtherServicesExcludingDepreciationAndAmortization" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="zinc_CostsOfGoodsSoldExcludingDepreciationAndAmortization" name="CostsOfGoodsSoldExcludingDepreciationAndAmortization" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="zinc_CreditAgreementAmountOutstanding" name="CreditAgreementAmountOutstanding" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="zinc_CreditAgreementExpirationDate" name="CreditAgreementExpirationDate" nillable="true" substitutionGroup="xbrli:item" type="xbrli:dateItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="zinc_CreditAgreementMember" name="CreditAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_CreditAgreementRemainingBorrowingCapacity" name="CreditAgreementRemainingBorrowingCapacity" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="zinc_CreditFacilityCreditPeriod" name="CreditFacilityCreditPeriod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_DebtInstrumentAdditionalInterestPayableOnDefault" name="DebtInstrumentAdditionalInterestPayableOnDefault" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="zinc_DebtInstrumentBasisSpreadOnVariableRateUnderConditionOne" name="DebtInstrumentBasisSpreadOnVariableRateUnderConditionOne" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_DebtInstrumentBasisSpreadonVariableRateduringAvailabilityPeriod" name="DebtInstrumentBasisSpreadonVariableRateduringAvailabilityPeriod" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_DebtInstrumentLetterofCreditfee" name="DebtInstrumentLetterofCreditfee" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="zinc_DebtInstrumentMaximumCashLeverageRatio" name="DebtInstrumentMaximumCashLeverageRatio" nillable="true" substitutionGroup="xbrli:item" type="xbrli:pureItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_DebtInstrumentMinimumNetProfitRequirement" name="DebtInstrumentMinimumNetProfitRequirement" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="zinc_DebtInstrumentMinimumTangibleNetWorthRequirement" name="DebtInstrumentMinimumTangibleNetWorthRequirement" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="zinc_DebtInstrumentPremium" name="DebtInstrumentPremium" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="zinc_DebtInstrumentRedemptionPriceFirst" name="DebtInstrumentRedemptionPriceFirst" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_DebtInstrumentRedemptionPriceSecond" name="DebtInstrumentRedemptionPriceSecond" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_DebtInstrumentRedemptionPrincipalAmount" name="DebtInstrumentRedemptionPrincipalAmount" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_DeferredPurchasePriceObligation" name="DeferredPurchasePriceObligation" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="zinc_DeferredTaxesRelatedToInitialCarryingAmountOfEmbeddedConversionOption" name="DeferredTaxesRelatedToInitialCarryingAmountOfEmbeddedConversionOption" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="zinc_DepositsAndOtherDisclosureTextBlock" name="DepositsAndOtherDisclosureTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="zinc_DepreciationAndAmortizationExpensesForPropertyPlantAndEquipmentLineItems" name="DepreciationAndAmortizationExpensesForPropertyPlantAndEquipmentLineItems" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_DerivativeSwapTypeFixedToVariableSwapContracts" name="DerivativeSwapTypeFixedToVariableSwapContracts" nillable="true" substitutionGroup="xbrli:item" type="us-types:perUnitItemType" xbrli:periodType="instant" />
  <xsd:element id="zinc_DerivativesInstrumentsProceedFromSellingOfRightRelatedToFutureBankruptcySettlement" name="DerivativesInstrumentsProceedFromSellingOfRightRelatedToFutureBankruptcySettlement" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="zinc_DilutiveSecuritiesIncludedAndAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" name="DilutiveSecuritiesIncludedAndAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="zinc_DocumentDocumentAndEntityInformationAbstract" name="DocumentDocumentAndEntityInformationAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_EnvironmentalObligations" name="EnvironmentalObligations" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="zinc_EquityInIncomeOfSubsidiariesNetOfTaxes" name="EquityInIncomeOfSubsidiariesNetOfTaxes" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="zinc_ExitandDisposalCostsExpectedCost" name="ExitandDisposalCostsExpectedCost" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="zinc_ExpectedexitandDisposalCostsincurred" name="ExpectedexitandDisposalCostsincurred" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="zinc_FixedChargeCoverageRatio" name="FixedChargeCoverageRatio" nillable="true" substitutionGroup="xbrli:item" type="xbrli:pureItemType" xbrli:periodType="instant" />
  <xsd:element id="zinc_FixedPortionOfNickelSwapContracts" name="FixedPortionOfNickelSwapContracts" nillable="true" substitutionGroup="xbrli:item" type="us-types:perUnitItemType" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="zinc_FixedPriceSwapsMember" name="FixedPriceSwapsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_FixedToVariableFutureSwapContractsCapacity" name="FixedToVariableFutureSwapContractsCapacity" nillable="true" substitutionGroup="xbrli:item" type="num:massItemType" xbrli:periodType="instant" />
  <xsd:element id="zinc_GainOnInsuranceRecoveryRelatedToFixedAssets" name="GainOnInsuranceRecoveryRelatedToFixedAssets" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="zinc_GuarantorFinancialInformationTextBlock" name="GuarantorFinancialInformationTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="zinc_HORSEHEADCORPORATIONMember" name="HORSEHEADCORPORATIONMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="zinc_HorseheadHoldingCorporationMember" name="HorseheadHoldingCorporationMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_IncrementalCommonSharesAttributableToShareBasedPaymentArrangementsRestrictedStock" name="IncrementalCommonSharesAttributableToShareBasedPaymentArrangementsRestrictedStock" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_InitialCarryingAmountOfEmbeddedConversionOption" name="InitialCarryingAmountOfEmbeddedConversionOption" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="zinc_InmetcoFacilityMember" name="InmetcoFacilityMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="zinc_InmetcoMember" name="InmetcoMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="zinc_InmetcoSeniorSecuredRevolvingCreditAgreementMember" name="InmetcoSeniorSecuredRevolvingCreditAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_InsuranceClaimLiabilities" name="InsuranceClaimLiabilities" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="zinc_InsuranceProceedsRelatedToFixedAssets" name="InsuranceProceedsRelatedToFixedAssets" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="zinc_InsuranceRecoveryRelatedExpense" name="InsuranceRecoveryRelatedExpense" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="zinc_InterestExpenseCapitalize" name="InterestExpenseCapitalize" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="zinc_InvestmentInAndAdvanceToFromSubsidiaries" name="InvestmentInAndAdvanceToFromSubsidiaries" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="zinc_InvestmentInAndAdvancesToAffiliates" name="InvestmentInAndAdvancesToAffiliates" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="zinc_LeadVariableToFixedContractsOutstanding" name="LeadVariableToFixedContractsOutstanding" nillable="true" substitutionGroup="xbrli:item" type="us-types:perUnitItemType" xbrli:periodType="instant" />
  <xsd:element id="zinc_LineOfCreditFacilityFrontingFeePercentage" name="LineOfCreditFacilityFrontingFeePercentage" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_LineOfCreditFacilityUnusedCapacityAdditionalFeePercentageduringAvailabilityPeriod" name="LineOfCreditFacilityUnusedCapacityAdditionalFeePercentageduringAvailabilityPeriod" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_LineOfCreditOneTimeFrontingFeePercentOfMaximumPrincipalAmount" name="LineOfCreditOneTimeFrontingFeePercentOfMaximumPrincipalAmount" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_LineofCreditFacilityAdditionalCapacityDuringAvailabilityPeriod" name="LineofCreditFacilityAdditionalCapacityDuringAvailabilityPeriod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="zinc_MaturityOfSeniorSecuredNotes" name="MaturityOfSeniorSecuredNotes" nillable="true" substitutionGroup="xbrli:item" type="xbrli:dateItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_MaximumBorrowingCapacityForLettersOfCredit" name="MaximumBorrowingCapacityForLettersOfCredit" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="zinc_MaximumDebtToEquityRatio" name="MaximumDebtToEquityRatio" nillable="true" substitutionGroup="xbrli:item" type="xbrli:pureItemType" xbrli:periodType="instant" />
  <xsd:element id="zinc_MaximumPeriodOfDeliverQuantitiesOfProduct" name="MaximumPeriodOfDeliverQuantitiesOfProduct" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_MinimumFixedChargeCoverageRatio" name="MinimumFixedChargeCoverageRatio" nillable="true" substitutionGroup="xbrli:item" type="xbrli:pureItemType" xbrli:periodType="instant" />
  <xsd:element id="zinc_MinimumPercentageOfAdvancesConsideredForCustomaryEventOfDefault" name="MinimumPercentageOfAdvancesConsideredForCustomaryEventOfDefault" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="zinc_MinimumUndrawnAvailabilityOfLineOfCreditWithInAnyBusinessDay" name="MinimumUndrawnAvailabilityOfLineOfCreditWithInAnyBusinessDay" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="zinc_MinimumUndrawnAvailabilityOfLineOfCreditWithInConsecutiveFiveBusinessDay" name="MinimumUndrawnAvailabilityOfLineOfCreditWithInConsecutiveFiveBusinessDay" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="zinc_MitsuiZincPowdersMember" name="MitsuiZincPowdersMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="zinc_MonacaPennsylvaniaFacilityMember" name="MonacaPennsylvaniaFacilityMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_NetBookValueOfRemainingAsset" name="NetBookValueOfRemainingAsset" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="zinc_NewZincFacilityMember" name="NewZincFacilityMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_NonconvertibleRate" name="NonconvertibleRate" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_NumberOfBroker" name="NumberOfBroker" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_NumberOfBusinessDays" name="NumberOfBusinessDays" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_NumberOfDomesticBanksInWhichCompanysCashBalanceConcentrated" name="NumberOfDomesticBanksInWhichCompanysCashBalanceConcentrated" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="instant" />
  <xsd:element id="zinc_NumberOfFacilities" name="NumberOfFacilities" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_NumberOfForeignBanksInWhichCompanysCashBalanceConcentrated" name="NumberOfForeignBanksInWhichCompanysCashBalanceConcentrated" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="instant" />
  <xsd:element id="zinc_NumberOfSuretyBondsOutstanding" name="NumberOfSuretyBondsOutstanding" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="zinc_OptionsAndSwapsMember" name="OptionsAndSwapsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_OtherLongTermLiabilities" name="OtherLongTermLiabilities" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="zinc_PaymentOfInsurancePremium" name="PaymentOfInsurancePremium" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="zinc_PercentageOfAssetsByNonGuarantorSubsidiaries" name="PercentageOfAssetsByNonGuarantorSubsidiaries" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_PercentageOfPrincipalAmountOfConvertibleNotesToRepurchase" name="PercentageOfPrincipalAmountOfConvertibleNotesToRepurchase" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element id="zinc_PercentageOfRevenuesByNonGuarantorSubsidiaries" name="PercentageOfRevenuesByNonGuarantorSubsidiaries" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_PercentageUnitOfZincExpectedForShipments" name="PercentageUnitOfZincExpectedForShipments" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="zinc_PlanTwoThousandTwelveMember" name="PlanTwoThousandTwelveMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_PrepaidExpensesAndOtherCurrentAssetsDisclosureTextBlock" name="PrepaidExpensesAndOtherCurrentAssetsDisclosureTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_PrepaidHedgeContractsExpenses" name="PrepaidHedgeContractsExpenses" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element id="zinc_ProceedsfromSaleofDerivatives" name="ProceedsfromSaleofDerivatives" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="zinc_PropertyDamageInsuranceRecovery" name="PropertyDamageInsuranceRecovery" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="zinc_PropertyPlantAndEquipmentUsefulLifeAndValuesAbstract" name="PropertyPlantAndEquipmentUsefulLifeAndValuesAbstract" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_RestrictedStockUnitsOutstanding" name="RestrictedStockUnitsOutstanding" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="instant" />
  <xsd:element id="zinc_RestrictedStockWithheldForTaxes" name="RestrictedStockWithheldForTaxes" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="zinc_ScheduleOfBalanceSheetTableTextBlock" name="ScheduleOfBalanceSheetTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_ScheduleOfCashFlowStatementTableTextBlock" name="ScheduleOfCashFlowStatementTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_ScheduleOfDepositsAndOtherTableTextBlock" name="ScheduleOfDepositsAndOtherTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_ScheduleOfIncomeStatementTableTextBlock" name="ScheduleOfIncomeStatementTableTextBlock" nillable="true" substitutionGroup="xbrli:item" type="nonnum:textBlockItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_SeniorSecuredDebtDiscount" name="SeniorSecuredDebtDiscount" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="zinc_SeniorSecuredNotesAdditionalMember" name="SeniorSecuredNotesAdditionalMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_SeniorSecuredNotesIssuePrice" name="SeniorSecuredNotesIssuePrice" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="zinc_SeniorSecuredNotesMember" name="SeniorSecuredNotesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_SeniorSecuredRevolvingCreditFacilityTerm" name="SeniorSecuredRevolvingCreditFacilityTerm" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_SettlementOfDerivativeContracts" name="SettlementOfDerivativeContracts" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="zinc_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsForfeitureRate" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsForfeitureRate" nillable="true" substitutionGroup="xbrli:item" type="num:percentItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_ShareBasedCompensationArrangementByShareBasedPaymentAwardRestrictedStockOptionsWeightedAverageGrantDateFairValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardRestrictedStockOptionsWeightedAverageGrantDateFairValue" nillable="true" substitutionGroup="xbrli:item" type="num:perShareItemType" xbrli:periodType="instant" />
  <xsd:element id="zinc_ShareBasedCompensationArrangementByShareBasedPaymentAwardRestrictedStockVestedIntrinsicValue" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardRestrictedStockVestedIntrinsicValue" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="zinc_ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesExpectedToBeIssued" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardSharesExpectedToBeIssued" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="zinc_StockOptionPlanTwoThousandSixMember" name="StockOptionPlanTwoThousandSixMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_StrikePriceOfDerivative" name="StrikePriceOfDerivative" nillable="true" substitutionGroup="xbrli:item" type="us-types:perUnitItemType" xbrli:periodType="instant" />
  <xsd:element id="zinc_TaxEffectFromShareBasedCompensationFinancingActivitiesNet" name="TaxEffectFromShareBasedCompensationFinancingActivitiesNet" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="zinc_TenPointFiveZeroPercentageSeniorSecuredNotesDueTwoZeroOneSevenMember" name="TenPointFiveZeroPercentageSeniorSecuredNotesDueTwoZeroOneSevenMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="zinc_ThreePointEightZeroPercentConvertibleSeniorNotesDueTwoThousandSeventeenMember" name="ThreePointEightZeroPercentConvertibleSeniorNotesDueTwoThousandSeventeenMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_UnderlyingShareAmountOfConvertibleNotes" name="UnderlyingShareAmountOfConvertibleNotes" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element id="zinc_UnearnedContractualServices" name="UnearnedContractualServices" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="zinc_ValueOfSuretyBondsOutstanding" name="ValueOfSuretyBondsOutstanding" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="zinc_VariableToFixedFutureSwapContractsCapacity" name="VariableToFixedFutureSwapContractsCapacity" nillable="true" substitutionGroup="xbrli:item" type="num:massItemType" xbrli:periodType="instant" />
  <xsd:element id="zinc_VariableToFixedFutureSwapContractsStrikePrice" name="VariableToFixedFutureSwapContractsStrikePrice" nillable="true" substitutionGroup="xbrli:item" type="us-types:perUnitItemType" xbrli:periodType="instant" />
  <xsd:element id="zinc_WriteOffOfAssetsInConnectionWithInsuranceRecovery" name="WriteOffOfAssetsInConnectionWithInsuranceRecovery" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="zinc_ZochemCreditFacilityMember" name="ZochemCreditFacilityMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="zinc_ZochemFacilityMember" name="ZochemFacilityMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="zinc_ZochemMember" name="ZochemMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
</xsd:schema>


